taxonID	type	description	language	source
912A944AEB0BFFEFFF71FDFCAA725595.taxon	discussion	Discussion. As given in the treatment of Section 1 of the complex (Reynoso-Velasco & Sites 2022), the most reliable unifying feature among species in the A. signoreti complex is in the ventral surface of the male phallosoma, which includes the presence of small protuberances (pointed or rounded) referred to as “ denticles ” on the sclerotized and variously shaped endosomal sclerites (e. g., Figs. 1 E – 1 G, 20 E). In a few species, the right sclerite is reduced, greatly reduced, or absent; nonetheless, the protuberances are present on the left sclerite, which also can be reduced (e. g., Fig. 35 E). Only one species, A. signoreti, lacks both sclerites and in consequence the protuberances; however, molecular evidence clearly supports the inclusion of the species in this complex (Reynoso-Velasco & Sites 2021). Additionally, the great majority of species in this complex, including A. signoreti, exhibit a characteristic maculation, as suggested but not described by La Rivers (1957 a). This feature includes extensive light-colored markings (sometimes spotted) at the lateral and posterior margins of the corium (e. g., Fig. 29 A). In some species, the marking on the posterior margin extends along the posterolateral angle of the corium (e. g., Fig. 35 A). For convenience, the A. signoreti complex was artificially organized into three sections (Table 1) based on conspicuous characteristics of the female subgenital plate: Section 1 includes females with posterolateral corners extending posteriorly slightly further than the central lobe (Fig. 1 H), Section 2 includes those females with the central lobe extending posteriorly further than the posterolateral corners (Fig. 1 I), and Section 3, where the females exhibit posterolateral corners and central lobe almost at the same level (Fig. 1 J).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB0BFFEFFF71FDFCAA725595.taxon	description	5 ’ – Female SGP with central lobe clearly extending posteriorly further than the posterolateral corners (Fig. 1 B) ......................................................................... Section 2 (refer to Reynoso-Velasco & Sites 2023) 5 ’’ – Female SGP with posterolateral corners and central lobe almost at the same level (Fig. 1 C) ............ Section 3 .......... 6 6 – Left margin of female SGP with a large lateral lobe that is truncate (Fig. 26 B) or evenly rounded (Fig. 35 B); SGP notoriously asymmetrical ........................................................................................ 7 6 ’ – Left margin of female SGP with a small lateral lobe that is rounded (Figs. 2 B, 4 B, 6 B, 9 B, 20 B, 23 B, 29 B, 37 B) or pointed to right-angled (Figs. 12 B, 15 B, 17 B); SGP asymmetrical (Figs. 4 B, 6 B, 9 B, 23 B) or symmetrical (Figs. 2 B, 12 B, 15 B, 17 B, 20 B, 29 B, 37 B) .......................................................................................... 8 7 – Female SGP with a plate-like and truncate lobe on the left margin; posterolateral corners asymmetrical, left corner lower (Fig. 26 B). Scutellum and corium with black-dotted pattern over reddish areas (Fig. 26 A) ............... A. scalenus La Rivers 7 ’ – Female SGP with an evenly rounded lobe on the left margin; posterolateral corners symmetrical, at the same level (Fig. 35 B). Scutellum and corium without pattern over light-brown to yellowish-brown areas (Fig. 35 A) ............ A. sitesi Reynoso 8 – Female SGP asymmetrical, lobe on left margin ventrally deflexed (Figs. 4 B, 23 B, 29 B) (bending more evident if specimen in caudal view and slightly tilted upward) .................................................................... 9 8 ’ – Female SGP asymmetrical (Figs. 6 B, 9 B) or symmetrical (Figs. 2 B, 12 B, 15 B, 17 B, 20 B, 37 B), lobe on left margin not deflexed ........................................................................................... 11 9 – Female SGP with posterolateral corners slightly reflexed dorsad (Fig. 4 B). Male accessory genitalic process (AGP) evenly curved from base to apex (Fig. 4 C) .................................................... A. cayo Sites & Shepard 9 ’ – Female SGP with posterolateral corners not reflexed (Figs. 23 B, 29 B). Male AGP angled close to base and at distal third (Figs. 23 C, 29 C) ......................................................................................... 10 10 – Female SGP with central lobe as two pointed lobes (Fig. 23 B). Male phallosoma rounded apically; endosomal sclerites present (Fig. 23 E). Both sexes with posterolateral corners of abdominal segments III and IV strongly produced and spinose (Fig. 23 A). Lateral area of pronotum and posterolateral area of corium with profuse dark-brown dotted pattern (Fig. 23 A) .............................................................................................. A. quadracies La Rivers 10 ’ – Female SGP with central lobe as two rounded lobes (Fig. 29 B). Male phallosoma pointed apically; endosomal sclerites absent (Fig. 29 E). Both sexes with posterolateral corners of abdominal segments III and IV barely produced (Fig. 29 A). Lateral area of pronotum and posterolateral area of corium without dotted pattern (Fig. 29 A) ....................... A. signoreti Stål 11 – Female SGP with apical lobes present (Fig. 9 B), although sometimes inconspicuous (Figs. 2 B, 37 B) .................. 12 11 ’ – Female SGP without apical lobes (Figs. 6 B, 12 B, 15 B, 17 B, 20 B) .............................................. 14 12 – Female SGP symmetrical (Figs. 2 B, 37 B) ................................................................. 13 12 ’ – Female SGP asymmetrical, lateral and pointed apical lobes on right margin slightly less developed (Fig. 9 B) ............. ................................................................................... A. dyticus La Rivers 13 – Female SGP with posterolateral corners rounded, central lobe wide (Fig. 37 B). Male phallosoma with endosoma not sclerotized apically (Fig. 37 E) .................................................................... A. sonorensis Usinger 13 ’ – Female SGP with posterolateral corners pointed, central lobe narrow (Fig. 2 B). Male phallosoma with endosoma apically sclerotized on left side, lobe-shaped (Fig. 2 E) .............................................. A. altiplanus Reynoso 14 – Female SGP with central lobe as two pointed lobes, these lobes and posterolateral corners similar in shape; lateral lobe on right margin inconspicuous (Fig. 6 B). Male right pseudoparamere 1.2 × as wide as left pseudoparamere (Fig. 6 D); phallosoma with right endosomal sclerite rounded and inconspicuous (Fig. 6 E). Body length ≤ 9.00 mm .................................................................................................... A. colimanus Polhemus & Polhemus 14 ’ – Female SGP with central lobe evenly rounded (Fig. 17 B) or as two rounded lobes (Figs. 12 B, 15 B), these lobes and posterolateral corners not similar in shape; lateral lobe on right margin conspicuous (Figs. 12 B, 15 B, 17 B, 20 B). Male pseudoparameres subequal in width (Figs. 12 D, 15 D, 17 D, 20 D); phallosoma with both endosomal sclerites knob-like (e. g., Fig. 20 E). Body length> 10.50 mm ................................................................................... 15 15 – Abdomen with posterolateral corners of segments III – IV slightly produced, acute but not spinose (Figs. 15 A, 17 A); dorsally with segments III – V usually narrowly exposed. Corium with light areas light-brown to yellowish-brown (Figs. 15 A, 17 A). Maximum width of pronotum 1.5 × length of pronotum and head at midline ...................................... 16 15 ’ – Abdomen with posterolateral corners of segments III – IV produced and clearly spinose (Figs. 12 A, 20 A); dorsally with segments III – V usually widely exposed. Corium with light areas usually reddish to reddish-brown (Figs. 12 A, 20 A). Maximum width of pronotum 1.6 × length of pronotum and head at midline ...................................................... 17 16 – Female SGP with posterior margin about 1 / 3 of SGP maximum width; central lobe shallowly concave medially, thereby as two low and rounded lobes; apices of lateral lobes at mid-length (Fig. 15 B) ............................ A. inecol Reynoso 16 ’ – Female SGP with posterior margin about 2 / 3 of SGP maximum width; central lobe evenly convex, no medial concavity; apices of lateral lobes clearly posterior to mid-length (Fig. 17 B) ................................... A. magniceps La Rivers 17 – Female SGP with shallowly concave central lobe slightly beyond level of posterolateral corners, posterior margin between posterolateral corners convex; posterolateral corners usually pointed (Fig. 12 B). Male pseudoparameres with posterolateral corners broadly rounded (Fig. 12 D); right phallosomal sclerite almost straight, basally directed (Fig. 12 E) .................................................................................................... A. hydor La Rivers 17 ’ – Female SGP with shallowly concave central lobe at same level as posterolateral corners, posterior margin almost straight; posterolateral corners usually rounded (Fig. 20 B). Male pseudoparameres with posterolateral corners narrowly rounded (Fig. 20 D); phallosomal sclerites (at least left one) right-tilted (Fig. 20 E) .......................... A. occidentalis La Rivers Annotated list of species (Section 3)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	description	(Figs. 2 – 3) Ambrysus altiplanus Reynoso in Reynoso-Velasco 2021 a: Zootaxa, 5005: 305 – 310 (original description).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	diagnosis	Diagnosis. This species can be distinguished from others in this section by the symmetrical female SGP with a small and rounded lateral lobe on each margin and inconspicuous apical lobes. Additionally, the posterolateral corners are short and pointed and the central lobe is shallowly concave medially, giving the appearance of a truncate lobe (Fig. 2 B). Also, the male phallosoma presents the endosoma apically sclerotized on the left side and lobe-shaped (Fig. 2 E black arrow) and both endosomal sclerites knob-like with conspicuous denticles (Fig. 2 E). Comparative notes. Ambrysus sonorensis Usinger is the only other species in this section with low and inconspicuous apical lobes on the female SGP; nonetheless, the posterior margin of the SGP in A. sonorensis is different because the rounded posterolateral corners and the central lobe are poorly developed, in some cases inconspicuous (truncate posterior margin). Females of A. dyticus La Rivers, also in this section, exhibit the SGP with apical lobes as well, but these are conspicuous and pointed. The condition of the sclerotized, lobe-shaped endosoma of A. altiplanus Reynoso is similar to the digitate endosoma of A. inecol Reynoso and A. magniceps La Rivers.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	discussion	Discussion. This species measures 12.64 – 14.00 in length and 7.88 – 8.19 in width. Although there is a superficial resemblance between A. altiplanus and A. sonorensis, the similarity of the male AGP (Fig. 2 C), pseudoparameres (Fig. 2 D), and endosoma suggests a closer relationship with A. inecol and A. magniceps. Relationship with the latter species is supported by recent evidence based on molecular data (Sites 2022).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	description	Variation. Some females exhibit the lateral lobe on the left margin of the SGP narrowly rounded or pointed.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	materials_examined	Type locality. Mexico: Durango: Mpio. Nombre de Dios, Río Mezquital at Puente Melones, km 239 carr. MEX 45 Vicente Guerrero-Durango, 23 ° 52 ’ 17.3 ’’ N, 104 ° 16 ’ 04.7 ’’ W. Repository. Female holotype (Fig. 2 A) is housed at the IEXA. Published records: MEXICO: Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, Querétaro, San Luis Potosí, Zacatecas (Reynoso-Velasco 2021 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	distribution	Distribution. Ambrysus altiplanus is distributed in north-central Mexico (Fig. 3) at elevations of 1500 – 2100 meters. The range includes localities in the western and southern areas of the Central Mexican Plateau, in the Chihuahuan Desert biogeographic province.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB06FFEDFF71FC71ACE951A2.taxon	materials_examined	Type material examined. HOLOTYPE ♀ (by original designation). MEXICO: Durango: Mpio. Nombre de Dios, km 239 carr. MEX 45 Vicente Guerrero-Durango, Pte. Melones, Río Mezquital, 23 ° 52 ’ 17.3 ’’ N, 104 ° 16 ’ 04.7 ’’ W, 1731 m, 29 - Jun- 2013, L- 1591, Reynoso-Velasco coll. PARATYPES: same data as holotype (2 ♂, 2 ♀ IEXA; 22 ♂, 23 ♀ UMC); same but 04 - Jan- 2014, L- 1721 (2 ♂, 2 ♀ CAS; 15 ♂, 6 ♀ UMC; 2 ♂, 2 ♀ USNM); Mpio. San Bernardo, San Bernardo, Río Sextín, 26 ° 00 ’ 05.0 ’’ N, 105 ° 30 ’ 17.6 ’’ W, 1607 m, 01 - Jan- 2014, L- 1711, Reynoso-Velasco coll. (4 ♂, 1 ♀ UMC); Mpio. Súchil, Corralitos, Arroyo Corralitos, 23 ° 31 ’ 11.1 ’’ N, 104 ° 08 ’ 13.3 ’’ W, 2091 m, 04 - Jan- 2014, L- 1720, Reynoso-Velasco coll. (4 ♂, 1 ♀ UMC). Chihuahua: Mpio. Balleza, El Padre, 6 km W of Balleza, Río de Agujas, 26 ° 57 ’ 01.8 ’’ N, 106 ° 24 ’ 00.8 ’’ W, 1572 m, 29 - Dec- 2013, L- 1701, Reynoso-Velasco coll. (2 ♂ UMC). Guanajuato: Mpio. Santa Cruz de Juventino Rosas, Arroyo Piedras Anchas [20 º 39 ’ 21.19 ’’ N, 100 º 59 ’ 27.6 ’’ W, 1765 m], 20 - Nov- 2010, R. Novelo coll. (1 ♂, 3 ♀ IEXA). Hidalgo: Mpio. Tecozautla, Río San Francisco at El Riíto, [7 km N of Tecozautla, 20 º 34 ’ 35.51 ’’ N, 99 º 37 ’ 19.13 ’’ W, 1590 m], 27 - Mar- 1996, J. A. Gómez-Anaya coll. (1 ♂, 1 ♀ CNIN; 2 ♂, 3 ♀ IEXA); same but 18 - Apr- 1996 (8 ♀ IEXA); same but 8 - May- 1996 (6 ♀ IEXA); same but 18 - Jun- 1996, A. Gómez, R. Arce & R. Novelo colls. (3 ♀ IEXA); Mpio. Tecozautla, Río San Francisco (El Riíto), 20 º 40 ’ 01 ’’ N, 99 º 30 ’ 06 ’’ W [most likely close to 20 º 34 ’ 47.54 ’’ N, 99 º 37 ’ 42.99 ’’ W], 1590 m, Jul- 1996, A. Gómez coll. (3 ♀ CNIN; 4 ♀ IEXA); [Mpio. Tecozautla], Río San Juan, [6 km NW of Gandhó, 20 º 33 ’ 48.9 ’’ N, 99 º 44 ’ 11.32 ’’ W, 1719 m], 28 - Mar- 1996, J. A. Gómez-Anaya coll. (1 ♂, 1 ♀ CNIN; 2 ♂, 1 ♀ IEXA). Jalisco: [Mpio. Degollado, Huáscato], trib. of Rio Lerma, [Prob. 20 º 28 ’ 38.80 ’’ N, 102 º 15 ’ 54.81 ’’ W, Approx. 1600 m], 13 - May- 1977, M. L. Smith & E. M. Baker / Ambrysus sp. Det. E. Bright, July 2003 (1 ♀ UMMZ); [Mpio. Yahualica de González Gallo], 5 mi N of Yahualica, Rio Ancho, trib. of Rio Verde [21 º 13 ’ 47.85 ’’ N, 102 º 51 ’ 2.48 ’’ W, 1670 m], 15 - Mar- 1961, Miller & Huddle colls., M 61 - 27 (1 ♂ UMMZ). Querétaro: Mpio. Tolimán, Panales, Rio Estorax [Extóraz], 20 º 52.33 N, 99 º 59.37 W, 1800 msnm, R. Jones coll. (1 ♂ IEXA; 1 ♂, 1 ♀ UAQE). San Luis Potosí: [Mpio. Santa María del Río] Rio Villeto [Prob. 6.3 – 9 mi S of Sta María on Hwy 57], Spring 1969, Barbour & Douglass (5 ♂, 9 ♀ USNM); [Mpio. Santa María del Río] Sta. María del Río, 9 - Dec- 1973, CL 602, J. T. Polhemus / Ambrysus magniceps La Rivers Det. J. T. Polhemus / looks good! I- 90 JTP / C. J. Drake Accession (1 ♂ USNM). Zacatecas: Mpio. Sain Alto, Sain Alto, Arroyo Frío, 23 ° 33 ’ 36.3 ’’ N, 103 ° 15 ’ 50 ’’ W, 2034 m 05 - Jan- 2014, L- 1722, Reynoso-Velasco coll. (3 ♂ UMC).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	description	(Figs. 4 – 5)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	discussion	Discussion. This species measures 9.60 – 10.88 in length and 6.24 – 6.88 in width. Sites & Shepard (2015) mentioned a similar condition of the asymmetrical SGP of A. cayo Sites & Shepard to be present in at least six Mexican species, of which, only A. cosmius La Rivers (Section 1), A. quadracies La Rivers, and A. scalenus La Rivers are members of the A. signoreti complex. This resemblance is only superficial as the shape of the male pseudoparameres and condition of the endosomal sclerites suggest a closer relationship with A. colimanus. This morphology-based proposition was supported by recent evidence based on molecular data (Sites 2022).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	description	Variation. No variation was detected on the diagnostic features.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	materials_examined	Type locality. Belize: Cayo District: Privassion Creek 16.6 km N of Augustine, 17 º 02.899 ’ N, 88 º 56.910 ’ W. Repository. Male holotype is housed at the UMC. Published record: BELIZE: Cayo District (Sites & Shepard 2015).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	distribution	Distribution. Ambrysus cayo is distributed in the west-central region of Belize, in the Cayo District (Fig. 5). The localities, all below 600 m, are in the Belize River Basin, in a small area of about 200 km 2 draining the northwestern slopes of the Pine Ridge system. This area is the southernmost section of the Veracruzan biogeographic province. It is likely that the species is at least present in the central-western part of the Petén Department, in northern Guatemala. This area is part of the same river basin and in close vicinity to locations where the species has been collected.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB05FFEAFF71FF49ABAB5475.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). BELIZE: Cayo District: Privassion Creek at road crossing, 16.6 km N of Augustine [= Douglas da Silva], 15 - IV- 2014, 486 m, 17 º 02.899 ’ N, 88 º 56.910 ’ W, L- 1723, R. W. Sites & W. D. Shepard colls., undercuts and marginal vegetation. PARATYPES: same data as holotype (1 ♀ UMC); same but 20 - IV- 2014, L- 1743 (1 ♂, 1 ♀ UMC); same but 07 - I- 1995, W. D. Shepard coll., WDS-A- 1118 (1 ♂ UMC); Rio On pools at 4.5 km N of Augustine, 16 º 59.2300 ’ N, 88 º 58.6240 ’ W, 459 m, 15 - IV- 2014, [L- 1725], R. W. Sites & W. D. Shepard colls., vegetated margins of bedrock pools (1 ♀ UMC); 1.7 km S of Augustine, unnamed stream, 06 - I- 1996, L- 96, R. W. Sites coll. (2 ♂, 1 ♀ UMC); 5.3 km S of Augustine, unnamed stream, 06 - I- 1996, W. D. Shepard coll. (1 ♂, 1 ♀ UMC); 8.4 km N of Augustine, unnamed stream, 17 º 00.8560 ’ N, 88 º 58.8180 ’ W, 445 m, 15 - IV- 2014, L- 1724, R. W. Sites & W. D. Shepard colls. (1 ♀ UMC). Additional material examined. BELIZE: Cayo District: Mountain Pine Ridge, trib. of Eastern Branch 1.7 mi S of Augustine, 06 - I- 1996, C. B. Barr coll. (2 ♂, 2 ♀ EMEC); same but 6 mi S of Augustine, (1 ♀ EMEC); Mountain Pine Ridge, Paddy Creek [between San Augustine and San Luis], N of San Luis, 31 - XII- 1973, CL 647, J. T. Polhemus coll. (1 ♀ USNM); Mountain Pine Ridge, [ca. 90 meters south of Paddy Creek], N of San Luis, 31 - XII- 1973, CL 648, J. T. Polhemus coll. (11 ♂, 16 ♀ USNM); Mountain Pine Ridge, N of San Augustine, [4 miles south of Privassion Creek], 31 - XII- 1973, CL 650, J. T. Polhemus coll. (1 ♂, 1 ♀ USNM).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	description	(Figs. 6 – 8)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) almost straight and parallel to body axis in basal two thirds, angled to right at approximately 90 degrees at distal third (Fig. 6 C). Medial lobes of tergum VIII (pseudoparameres) asymmetrical, right pseudoparamere 1.2 × wider (at widest point) than left pseudoparamere, posterolateral and posteromesal corners broadly rounded, posterior margin shallowly convex (Fig. 6 D). Phallosoma elongate, linear, slender, tapering dorsoapically; left endosomal sclerite subtriangular, with transverse row of inconspicuous denticles; right endosomal sclerite small, rounded, lightly sclerotized, inconspicuous, without apparent denticles (Fig. 6 E). Parameres symmetrical, almost as long as maximum width, mesal margin almost straight. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface (Fig. 6 F), with thick brush of elongate setae on posterior margin (not clearly seen in Fig. 6 F as those were unintentionally eliminated during the digital editing of the figure).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	diagnosis	Diagnosis. Ambrysus colimanus can be distinguished from other species in this section by the asymmetrical female SGP with a small and rounded lateral lobe on the left margin. Additionally, the pointed posterolateral corners and central lobes are similarly shaped, giving the posterior margin of the SGP the appearance of an upsidedown four-spiked crown (Fig. 6 B). Also, males exhibit a rounded right endosomal sclerite with no denticles and a subtriangular left endosomal sclerite with a few low denticles (Fig. 6 E). Furthermore, the small size and contrasting pattern of dark-brown and light-brown on the dorsum (Fig. 6 A) clearly distinguish this species from others in the complex. The asymmetrically wide pseudoparameres in males of A. colimanus is a unique feature not seen in any other species of the subgenus Ambrysus. Comparative notes. This is the smallest species in the A. signoreti complex (length ≤ 9.00 mm). The crown shape of the female SGP and asymmetrical pseudoparameres in the males make this species unique among members of the complex. The shape of the male endosomal sclerites is similar to that exhibited by A. brailovskyi and A. cayo. A similar small and rounded right endosomal sclerite is also present in A. inflatus La Rivers (Section 2).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	discussion	Discussion. This species measures 7.40 – 9.00 in length and 4.60 – 5.50 in width. At the time of the description, the authors (Polhemus & Polhemus 1981) compared this species to A. signoreti Stål, stating that the shape of the SGP was similar between the two species, except for the “ flared ” lateral lobes present in the latter. Actually, in addition to the lateral lobes, the shape of the posterior margin in both species is distinct from each other. The posterolateral corners and the bilobed central lobe in A. colimanus are particularly similar in shape, whereas the posterolateral corners of A. signoreti are pointed and the lobes of the central lobe clearly rounded. Furthermore, the overall shape of the SGP in A. colimanus is subquadrate, whereas it is subtriangular in A. signoreti. Polhemus and Polhemus (1981) considered the “ prominent ” maculation in A. colimanus to be similar to that exhibited by A. lunatus Usinger (Section 2). A similar contrasting pattern is exhibited by A. sitesi Reynoso. In the study on the phylogeny of Cryphocricinae (Reynoso-Velasco & Sites 2021), A. colimanus was sister to a clade with seven species, including those with similarly shaped endosomal sclerites (see Comparative notes), whereas the study on the phylogeny of Naucoridae (Sites 2022) recovered a close relationship of A. colimanus and A. cayo.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	description	Variation. Some females exhibit the SGP with rounded posterolateral corners. Also, some females exhibit a low and rounded lateral lobe on the right margin, giving the impression of an almost symmetrical SGP. The male AGP can be angled at approximately 45 degrees at the distal third. Additionally, some males can present the right endosomal sclerite so lightly sclerotized that it is difficult to distinguish.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	materials_examined	Type locality. Mexico: Colima: Mpio Armería, Armería River east of Armería town. Repository. Male holotype (Fig. 7 A) is housed at the USNM. Published records: MEXICO: Colima, Jalisco Michoacán, Nayarit, Oaxaca (Polhemus & Polhemus 1981; Reynoso-Velasco & Sites 2018 a, 2018 b, 2019 b; Reynoso-Velasco 2021 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	distribution	Distribution. Ambrysus colimanus is distributed exclusively in Mexico. Its characteristic neotropical distribution includes the lowlands along the west coast from Nayarit south to Oaxaca (Fig. 8). The species records are in the narrow area of the Pacific Lowlands biogeographic province. The apparent disjunct distribution is due to the lack of collections along the coast in the state of Guerrero.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB03FFF7FF71FD6CAD615060.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). MEXICO: Colima: [Mpio. Armería], Ameria [Armería] River, [east of Armería Town], 26 - XI- 1968, CL 1229, J. T. Polhemus coll. PARATYPES: same data as holotype (1 ♀ CAS; 1 ♂ CNIN; 4 ♂, 3 ♀ USNM). Additional material examined. MEXICO: Colima: Mpio. Armería, Río Armería at Cofradía de Juárez (Periquillo), 3 km NE of Armería, 18 ° 57 ’ 16.8 ’’ N, 103 ° 56 ’ 45.7 ’’ W, 36 m, 24 - Jun- 2013, L- 1571, Reynoso-Velasco coll. (2 ♂, 4 ♀ CNIN; 5 ♂, 4 ♀ IEXA; 17 ♂, 14 ♀ UMC). Jalisco: Arroyo Pueblo Nuevo, trib. of Río Chacala, at approx. 18 mi N of Santiago, 03 - III- 1955, R. R. Miller & J. T. Greenbank, M 55 - 45 (6 ♂ UMMZ); [Mpio. La Huerta], Cuitzmala, 30 - IV- 1976, H. Brailovsky / Colección del Instituto de Biología, UNAM, México D. F. (1 ♀ UMC); [Mpio. La Huerta], Río Apamila 2 mi NW of La Huerta, 10 - Mar- 1957, R. R. M. Miller (3 ♂, 1 ♀ UMMZ); [Mpio. La Huerta], Río Cuitzmala, 2.5 km N of Emiliano Zapata, 6 - Jan- 2005, C. B. Barr (1 ♂, 2 ♀ EMEC; 1 ♂ UMC); [Mpio. La Huerta], Río Purificación at bridge 2.2 mi W of La Huerta, 20 - Feb- 1976, R. R. & F. H. Miller & J. T. Greenbank, M 76 - 32 (2 ♂, 1 ♀ UMMZ); Mpio. Puerto Vallarta, La Desembocada, 20 ° 43 ’ 36.5 ’’ N, 105 ° 09 ’ 25.7 ’’ W, 39 m, 26 - Jun- 2013, L- 1577, Reynoso-Velasco coll. (1 ♂, 1 ♀ UMC); Mpio. Puerto Vallarta, Las Palmas, 235 m, 20 º 49 ’ 51.5 ’’ N, 105 º 05 ’ 36.7 ’’ W, 16 - Mar- 2014, Gómez, J., Smith, S. & Novelo, R. (1 ♂ IEXA); Mpio. Puerto Vallarta, Las Palmas de Arriba, 26 - Jun- 2013, L- 1578 / 120 m, 20 º 49 ’ 31.3 ’’ N 105 º 05 ’ 25.3 ’’ W, Reynoso-Velasco coll. (1 ♂, 1 ♀ UMC); Río Cuitzmala SE of Chamela, 6 - I- 2005, 180 ’ / William D. Shepard leg. (2 ♂, 1 ♀ EMEC). Michoacán: Mpio. Aquila, Aquila, Pte. Ramal Aquila, L- 1487, 25 - Dec- 2012 / 159 m, 18 º 35 ’ 08.1 ’’ N 103 º 30 ’ 51.8 ’’ W, Reynoso-Velasco coll. (1 ♂, 1 ♀ CNIN; 1 ♂, 3 ♀ IEXA; 10 ♂, 12 ♀ UMC); Mpio. Aquila, El Duín, Río Ostula at Pte. Ostula, 26 - Dec- 2012, L- 1489 / 12 m, 18 º 27 ’ 50.1 ’’ N 103 º 32 ’ 34.1 W, Reynoso-Velasco coll. (1 ♂, 1 ♀ CNIN; 1 ♂, 2 ♀ IEXA; 4 ♂, 9 ♀ UMC); Mpio. Aquila, Santa Cruz de Cachán, Río Coalcomán at Pte. Cachán, L- 1491, 26 - Dec- 2012 / 8 m, 18 º 15 ’ 02.5 ’’ N 103 º 14 ’ 42.2 ’’ W, Reynoso-Velasco coll. (2 ♀ CNIN; 3 ♂, 2 ♀ IEXA; 5 ♂, 25 ♀ UMC); Mpio. Chinicuila, Villa Victoria, 03 - Jun- 2005, Novelo, R. coll. (1 ♂ IEXA); Mpio. Coalcomán, La Chichihua, 10 - Jul- 2005, R. Novelo & J. A. Gómez colls. (2 ♂ IEXA); Mpio. Morelos, La Placita de Morelos, Río Aquila at Pte. La Placita, 26 - Dec- 2012, L- 1488 / 7 m, 18 º 32 ’ 19.9 ’’ N 103 º 35 ’ 17.9 ’’ W, Reynoso-Velasco coll. (1 ♂, 1 ♀ UMC). Nayarit: [Mpio. Compostela], El Refilio [Refilión], 2800 ’, CL 729, 8 - VI- 1975, J. T. Polhemus (1 ♀ USNM); [Mpio. San Blas], Mecatán, 5 - VIII- 84, M. García / Colección del Instituto de Biología, UNAM, México D. F. (1 ♂ UMC); 7 mi S of Tepic, 26 - VII- 1963, Paul J. Spangler / C. J. Drake Accession (1 ♀ USNM). Oaxaca: Mpio. Mártires de Tacubaya, Mártires de Tacubaya, 29 - May- 2012, L- 1390 / 206 m, 16 º 34 ’ 41.1 ’’ N 98 º 13 ’ 08.7 ’’ W, Reynoso-Velasco coll. (3 ♂, 2 ♀ UMC); Mpio. San Gabriel Mixtepec, Río Rana, km 194 carr. Puerto Escondido-Oaxaca, San Gabriel Mixtepec, L- 1380 / 27 - May- 2012; 712 m, 16 º 06 ’ 06.3 ’’ N, 97 º 03 ’ 52.9 ’’ W, Reynoso-Velasco coll. (1 ♂, 1 ♀ IEXA; 2 ♂, 7 ♀ UMC); same but 03 - Apr- 2015, L- 1906, Reynoso-Velasco, Sites, Shepard & Barr colls. (1 ♂, 3 ♀ UMC); Mpio. San Miguel del Puerto, Copalita, Río Copalita at Pte. Copalita, 15 ° 49 ’ 12.2 ’’ N, 96 ° 03 ’ 57.6 ’’ W, 28 m, 04 - Jun- 2014, L- 1818, Reynoso-Velasco coll. (1 ♂, 2 ♀ IEXA); Mpio. San Pedro Huamelula, Morro Ayutla, Río Ayutla at Pte. Río Ayutla, 15 ° 54 ’ 08.7 ’’ N, 95 ° 51 ’ 13.3 ’’ W, 29 m, 4 - Jun- 2014, L- 1816, Reynoso-Velasco coll. (2 ♂, 1 ♀ IEXA).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	description	(Figs. 9 – 11)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 30 degrees close to proximal third, angled again at approximately 75 degrees at distal third (Fig. 9 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral corners produced and narrowly rounded, posteromesal corners broadly rounded, posterior almost margin straight (Fig. 9 D). Phallosoma elongate, linear, slender, tapering dorsoapically; left endosomal sclerite subtriangular, with inconspicuous denticles; right endosomal sclerite knob-like, with inconspicuous denticles (Fig. 9 E). Parameres symmetrical, almost as long as maximum width, mesal margin slightly convex. Proctiger as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 9 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	diagnosis	Diagnosis. This species can be easily distinguished from the rest in this section by the distinctive presence of pointed and conspicuous apical lobes on the female SGP (Fig. 9 B). Comparative notes. Ambrysus dyticus is unique among species in this complex because it is the only one with the female SGP with distinct and pointed apical lobes. Ambrysus altiplanus and A. sonorensis also present apical lobes, but they are poorly developed and inconspicuous.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	discussion	Discussion. This species was reported to measure 9.50 – 11.00 in length and 6.75 – 7.50 in width (La Rivers 1953 b). At the time of its description, La Rivers considered the female SGP and male AGP of this species to be similar to those of his A. occidentalis La Rivers; nonetheless, he did not consider these features to be an indication of close relatedness, as the two species exhibit differences in body proportions and convexity. In fact, the AGP is, to some extent, comparable between the two species, but the shape of the SGP is quite contrasting. Superficially, this species more closely resembles the Central American A. variegatus Usinger (Section 1). Recent phylogenetic studies on Cryphocricinae (Reynoso Velasco & Sites 2021) and Naucoridae (Sites 2022) did not include A. dyticus. The single female specimen from El Salvador in the CAS has a label that reads “ Homotype ” and was identified by Usinger as Ambrysus lundbladi Usinger (Section 2; listed in the Material examined section); this indicates the author considered this specimen to be conspecific with his species from central Mexico. This inaccurate concept could be based on an “ overall ” dorsal similarity of the two specimens (A. lundbladi was described based on a single female), because the shape of the SGP is noticeably different.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	description	Variation. In the original description and based on specimens from two localities in Guatemala, La Rivers (1953 b) reported a general “ quadrisinuate ” posterior margin of the female SGP of A. dyticus (Figs. 9 B, 10 A bottom). According to the author (La Rivers 1953 b), this generalized shape could exhibit some variation depending on proportions of the posterolateral corners and central lobe, including: 1) corners and central lobe only slightly developed (Fig. 10 B bottom); 2) corners and central lobe poorly developed and inconspicuous, giving the appearance of a truncate posterior margin (Fig. 10 C bottom); and 3) corners conspicuous and central lobe poorly developed and inconspicuous (Fig. 10 D bottom). Additionally, each of these SGP variants had its corresponding male AGP alternative form, which exhibited slight variation on the length and shape of the apex (Figs. 10 A – 10 D top). Based on the specimens we have examined, even when some of this variation on the posterior margin of the SGP is present, the presence of pointed apical lobes indicates the specimen belongs to A. dyticus.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	materials_examined	Type locality. Guatemala: Santa Rosa: Lago Ayarza. Repository. La Rivers (1953 b) reported that the male holotype, allotype, and several paratypes were deposited in the SEMC; however, Andrew Short (pers. com., October 2021) informed us that the holotype is not there; only five paratypes were present. Thus, the repository of the holotype is unknown. In the original description, La Rivers (1953 b) reported the type material to be deposited only in the SEMC (several specimens) and the UMMZ (one specimen). The single specimen at the UMMZ is from 10 km SW of Cuilapa (Guatemala). We found four specimens at the USNM from the Cuilapa locality bearing La Rivers’ A. dyticus paratype labels (see Material examined); thus, these specimens could have been donated to the USNM after the species description. Published records: EL SALVADOR: Chalatenango, Cuscatlán; GUATEMALA: Baja Verapaz, Guatemala, Santa Rosa; HONDURAS: Francisco Morazán; MEXICO: Chiapas (La Rivers 1953 b, Herrera 2013, Reynoso-Velasco 2023). Reynoso-Velasco (2023) stated that the specimens (housed at the CAS) used by Herrera (2013) to report this species from Mexico represented misidentifications; thus, those records from the states of Jalisco and Nayarit are incorrect. Additionally, Herrera (2013) reported this species from Nicaragua, but the specimens were not found at the CAS (Reynoso-Velasco 2023); hence, this record needs to be confirmed.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	distribution	Distribution. Ambrysus dyticus is a Central American species distributed from the southernmost part of Mexico to Honduras (Fig. 11). Records are predominantly within the Chiapas Highlands biogeographic province, at elevations between 500 and 2000 meters.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1EFFF3FF71F918AD7057C5.taxon	materials_examined	Type material examined. PARATYPES: GUATEMALA: [Santa Rosa]: Lake Ararza [Ayarza], 11 - V- 1947, M 47 - 60, R. R. Miller (1 ♀ SEMC); same but M 47 - 18 (1 ♂ SEMC); [Mpio. Cuilapa], 10 km SW of Cuilapa, 21 - IV- [1946] / 1946 R. R. Miller / Ambrysus dyticus La Rivers Paratype (2 ♂, 1 ♀ USNM); same but Ambrysus dyticus La Rivers determined by Ira La Rivers ‘ 50 (1 ♂ USNM). Additional material examined. EL SALVADOR: Chalatenango: [Mpio. La Palma], San José Sacare, 14 - III- 1927, R. A. Stirton coll. / Homotype / Ambrysus lundbladi Usinger det. by R. L. Usinger / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS). Cuscatlán: [Mpio. El Rosario]. [El] Rosario, Nº 444 - 547 B, 23 - III- 1955, M. S. V. coll. (3 ♂, 3 ♀ USNM); same but Salazar coll. (2 ♂, 3 ♀ USNM). GUATEMALA: Baja Verapaz: [Mpio. Salamá], Río Quililá, VI- 2011, R. S. Zack (1 ♂, 1 ♀ IEXA; 1 ♂, 1 ♀ UMC); same but Río Quililá on Rt. 5 (old road) to Salamá from Rt. CA- 14, 15 º 13.913 ’ N, 90 º 17.662 ’ W, 1,355 m, 15 - IX- 2009, R. S. Zack & J. Monzón colls. (2 ♂, 2 ♀ UMC). Guatemala: [Mpio. Ciudad de Guatemala], 14 km E of Guat [emala] City, 28 - III- [1946] / R. R. Miller 1946 (1 ♂ USNM); same but 18 km E of Guat [emala] City, 24 - III- [1946] (4 ♂ USNM); same but 10 mi S of Guatemala City, 5 - VIII- 1965, Paul. J. Spangler (1 ♀ USNM); 50 km E of Guat [emala] City, 11 - III- [1946] (2 ♀ USNM). HONDURAS: Francisco Morazán: [Mpio. San Antonio de Oriente], El Zamorano, 14 º 01 ’ N, 87 º 00 ’ W, 850 m / Estudiante EAP / 77.431 (1 ♀ EAPZ); same but / 77.421 (1 ♂ EAPZ). MEXICO: Chiapas: [Mpio Cacahoatán]: Río Colorado [Maxaum at Pte. Colorado], 21 - IV- 1983, H. Brailovsky coll. / Colección del Instituto de Biología, UNAM. México D. F. / C. J. Drake Accession (1 ♀ USNM); same but E. Barrera coll. (1 ♀ USNM).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	description	(Figs. 12 – 14)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 30 degrees at proximal third, angled again at approximately 80 degrees at distal third (Fig. 12 C) Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral and posteromesal corners broadly rounded, posterior margin shallowly concave medially (Fig. 12 D). Phallosoma elongate, linear, slender, tapering dorsoapically; endosomal sclerites knob-like, with small denticles (Fig. 12 E). Parameres symmetrical, slightly longer than maximum width, mesal margin convex. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 12 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	diagnosis	Diagnosis. Ambrysus hydor La Rivers can be distinguished from other species in the section by the symmetrical SGP with pointed to right-angled lateral lobes at mid-length of each margin. Additionally, the posterolateral corners are small and pointed and the central lobe is indistinctly concave medially. Also, the male phallosoma presents both endosomal sclerites knob-like with small denticles. Comparative notes. This species is superficially most similar to A. occidentalis and A. scalenus because of the overall dorsal coloration, including the light-brown to reddish with dark-brown spots markings on the corium. Nevertheless, the “ more ” elliptical body form and particular shapes of markings on the corium give this species a closer resemblance to A. occidentalis than to A. scalenus, to the point that the two species are almost superficially indistinguishable (compare Fig. 12 A to Fig. 20 A). The main difference between the two species is that the posterior margin of the female SGP is almost straight in A. occidentalis (central lobe low and at same level as the posterolateral corners), whereas the central lobe in A. hydor extends slightly further posteriorly (not to the point to consider this species a member of Section 2 of the complex, where the central lobe clearly extends posteriorly further than the posterolateral corners). Additionally, males of this species exhibit pseudoparameres with posterolateral corners broadly rounded, whereas males of A. occidentalis have these corners narrowly rounded. The spinose posterolateral corners of abdominal segments III – V in males and females of A. hydor are generally more developed (robust).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	discussion	Discussion. This species measures 10.62 – 12.50 in length and 7.25 – 8.50 in width. Although different aspects of the morphology of this species are similar to those of A. occidentalis, the recent phylogenetic analysis (Reynoso-Velasco & Sites 2021) suggests that A. hydor is more closely related to A. henryi Reynoso & Sites (Section 2), and together these two species are sister to A. occidentalis. La Rivers (1953 a) reported the female allotype to be a specimen from Jalisco (Unión de Tula), which is housed at the SEMC. In addition to the Jalisco specimen, we also examined another allotype-label bearing specimen, which is a female from Estado de México (Tejupilco) housed at the CAS; most probably La Rivers misplaced the allotype label on this latter specimen. Also, in the original description, La Rivers reported an unspecified number of paratypes collected in Tejupilco on 19 June 1933. We examined three specimens (1 ♀ CAS; 1 ♂, 1 ♀ EMEC) bearing La Rivers’ A. hydor paratype labels from this locality, but only the female in the CAS was collected on the date reported in the original description; however, we consider the specimens in the EMEC to be valid paratypes as they have La Rivers’ handwritten paratype labels and because the only information that differs from that in the original description is the day the specimens were collected at the reported locality (see Type material examined section). Contrarily, a female in the CAS from the state of Sinaloa (Mazatlán) and a female in the SEMC from the state of Aguascalientes, both specimens bearing La Rivers’ A. hydor paratype labels, are herein not considered as valid paratypes, because neither the locality nor the state was reported in the original description (see Additional material examined section). An early concept of the species boundaries in the genus Ambrysus, as well as the variation on the shape of the female SGP of this species and A. occidentalis (see Variation sections of both species) and the almost identical dorsal appearance of the two species most likely resulted in the identification by DRV of some specimens deposited in different collections as belonging to A. hydor when they were actually members of A. occidentalis, or vice versa; consequently, further examination that also considers important features of the males is necessary to clearly establish whether those specimens belong to A. hydor or A. occidentalis. These specimens, mostly from northwestern Mexico where the species distributions overlap, were not included in this study (to the best of our knowledge).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	description	Variation. Some females exhibit the SGP with the lateral lobes more developed, posteriorly directed, and clearly pointed. The posterolateral corners can be small and rounded or inconspicuous. In some cases, the central lobe is not concave medially. Also, females can present an asymmetrical SGP with a slightly smaller lateral lobe on the right margin or the left lateral lobe pointed and that on the right margin right-angled. Some males exhibit the left endosomal sclerite less developed, thereby reducing its knob-like shape.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	materials_examined	Type locality. Mexico: Morelos: Río Amacuzac at kilometer 133 south of Mexico City. Repository. Male holotype (Fig. 13 A) is housed at the SEMC. Published records: MEXICO: Estado de México, Guerrero, Jalisco, Michoacán, Morelos (La Rivers 1953 a; Reynoso-Velasco & Sites 2016 a, 2018 a, 2018 b). The record from Guerrero reported in the original description (La Rivers 1953 a) was based on paratypes with label data indicating they were collected by H. D. Thomas at La Sabana and Puente de Ixtla, Guerrero. In fact, the town of Puente de Ixtla and the homonymous municipality are political and administrative divisions of the contiguous state of Morelos; thus, this particular record is inaccurate.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	description	New records: Mexico: Aguascalientes, Colima, Nayarit, Oaxaca, Puebla, Sinaloa, Sonora.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	distribution	Distribution. Ambrysus hydor is distributed exclusively in Mexico, along the central and northwestern parts of the country (Fig. 14). This species exhibits a predominantly neotropical distribution that includes watercourses below 2,000 meters, with the majority of records within the Balsas Basin and the northern section of the Pacific Lowlands biogeographic provinces.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB1AFFFCFF71FDFCA9C853D5.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). MEXICO: Morelos: Río Amacuzac, Morelos, kil. 133 S Mex. City, 14 - X- [19] 36, H. D. Thomas / Ambrysus hydor La Rivers HOLOTYPE. PARATYPES: Estado de México: Tejupilco, Mex. Temescaltepec [Temascaltepec], 15 - VI- [19] 33, H. E. Hinton & R. L. Usinger colls. / Ambrysus hydor La Rivers Allotype [incorrectly labeled as allotype; in the original description the allotype was reported to be a specimen from Jalisco and housed at the SEMC] / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 / Paratype Ambrysus hydor La Rivers det. [in] 1970 by Vincent Lee / Univ. of Kansas has the published allotype, 06 - XII- [19] 78, V. F. Lee (1 ♀ CAS); Tejupilco, Mex. Temescaltepec [Temascaltepec], 21 - VI- [19] 33 / H. E. Hinton & R. L. Usinger colls. / Ambrysus hydor La Rivers Paratype / Ambrysus hydor La Rivers determined by Ira La Rivers 1948 (1 ♀ EMEC); same but 19 - VI- [19] 33 / 101 / to be compared with Ambrysus signoreti Stål # 2 (1 ♂ EMEC); Tejupilco, Mex. Temescaltepec [Temascaltepec], 23 - VI- [19] 33 / H. E. Hinton & R. L. Usinger colls. / Ambrysus hydor La Rivers Paratype / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS). Guerrero: La Sabana, kil. 226 S of Mex. City, 20 - X- [19] 36, H. D. Thomas coll. / Ambrysus hydor La Rivers Paratype (1 ♀ SEMC). Jalisco: [Mpio. Unión de Tula], Unión de Tula, 16 - IX- [19] 38, H. D. Thomas / Ambrysus hydor La Rivers Allotype (1 ♀ SEMC) [specimen reported as the allotype in the original description]; [Mpio. Unión de Tula], Unión de Tula, 16 - IX- [19] 38, H. D. Thomas / Ambrysus hydor La Rivers Paratype (1 ♀ SEMC). Michoacán: [Mpio.] Uruapan, El Sabino, 28 - VII- 1936, H. D. Thomas / Ambrysus hydor La Rivers Paratype (1 ♀ SEMC). Morelos: [Mpio. Puente de Ixtla], Puente de Ixtla, Gro. [Morelos], 12 - VII- [19] 37, H. D. Thomas coll. / Ambrysus hydor La Rivers Paratype (1 ♀ EMEC; 1 ♀ SEMC); same but / donated to AMNH by J. T. Polhemus (1 ♀ USNM). Additional material examined. MEXICO: Aguascalientes: 5 mi S of Aguascalientes, 16 - VII- [19] 34, Smith & Dunkle colls. / Ambrysus hydor La Rivers Paratype (1 ♀ SEMC) [locality not reported in the original description]. Colima: Mpio. Armería, Río Armería at Cofradía de Juárez (Periquillo), 3 km NE of Armería, 18 ° 57 ’ 16.8 ’’ N, 103 ° 56 ’ 45.7 ’’ W, 36 m, 24 - VI- 2013, L- 1571, Reynoso-Velasco, D. coll. (2 ♂, 2 ♀ UMC); Mpio. Comala, Río Armería SE of Zacualpan, 19 ° 19 ’ 38.8 ’’ N, 103 ° 48 ’ 50.1 ’’ W, 461 m, 23 - VI- 2013, L- 1568, Reynoso-Velasco, D. coll. (1 ♀ UMC); Mpio. Coquimatlán, Río Colima at Los Amiables, 19 ° 09 ’ 48.9 ’’ N, 103 ° 50 ’ 06.9 ’’ W, 288 m, 23 - VI- 2013, L- 1570, Reynoso-Velasco, D. coll. (2 ♀ IEXA); Mpio. Piscila, Río Salado at Pte. El Salado, 19 ° 11 ’ 39.8 ’’ N, 103 ° 41 ’ 37.9 ’’ W, 371 m, 23 - VI- 2013, L- 1567, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA; 3 ♂, 2 ♀ UMC). Estado de México: km 10 [carr.] Tejupilco-Temascaltepec, 20 - X- 1983, E. Barrera / Colección del Instituto de Biología, UNAM, México D. F. / C. J. Drake Accession (1 ♂ USNM); Mpio. Luvianos, Caja de Agua, 18 º 57 ’ 58 ’’ N, 100 º 17 ’ 30.9 ’’ W, 1079 m, L- 1460, 20 - XII- 2012, Reynoso-Velasco, D. coll. (2 ♂ IEXA; 1 ♂, 1 ♀ UMC); Mpio. Santo Tomás de los Plátanos, Santa Bárbara, in front of Sta. Bárbara hydroelectric plant, 19 º 10 ’ 29.4 ’’ N, 100 º 17 ’ 20.4 ’’ W, 1051 m, L- 1463, 20 - XII- 2012, Reynoso-Velasco, D. coll. (4 ♂, 9 ♀ UMC); Mpio. Tejupilco, Arroyo Paso de Vigas at Paso de Vigas, 18 º 53 ’ 32.6 ’’ N, 100 º 13 ’ 57.0 ’’ W, 1107 m, L- 1459, 19 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♀ IEXA; 2 ♂, 2 ♀ UMC); same but L- 1909, 05 - IV- 2015, Reynoso, Sites, Shepard & Barr colls. (4 ♂, 2 ♀ IEXA); Mpio. Tejupilco, Río Bejucos at Bejucos, 700 m, 22 - IV- 2004, R. Novelo coll. (1 ♂, 1 ♀ IEXA); Tejupilco, Mex. Temescaltepec [Temascaltepec], VII- 1934 / H. E. Hinton (1 ♂ EMEC). Guerrero: km 154 carr. Iguala-Cd. Altamirano, 23 - XI- 1984, M. Vértiz coll. / Colección del Instituto de Biología, UNAM, México D. F. / C. J. Drake Accession (1 ♀ USNM); [Mpio. Acapulco], Acapulco, 14 - VII- 1937 / Ambrysus magniceps La Rivers det. J. R. Davis [19] 95 (1 ♂ SEMC); Mpio. Atenango del Río, Río Amacuzac at Atenango del Río, 18 º 06 ’ 01.5 ’’ N, 99 º 06 ’ 27.8 ’’ W, 631 m, 30 - XII- 2012, L- 1499, Reynoso-Velasco, D. coll. (2 ♂ UMC); [Mpio. Chilpancingo de los Bravo], Acahuizotla, 27 - VI- 1983, M. Marcía coll. / Colección del Instituto de Biología, UNAM, México D. F. / C. J. Drake Accession (1 ♀ USNM); Mpio. Copalillo, Río Balsas (Río Papalutla o Atoyac) at Papalutla, 18 º 01 ’ 27 ’’ N, 98 º 54 ’ 09.3 ’’ W, 627 m, L- 1500, 30 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♀ IEXA); Mpio. Coyuca de Catalán, carr. Zihuatanejo-Coyuca de Catalán, Río Los Placeres nr. Placeres del Oro, 18 º 12 ’ 50.8 ’’ N, 100 º 53 ’ 23 ’’ W, 382 m, L- 1495, 28 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA; 3 ♂, 4 ♀ UMC); Mpio. Coyuca de Catalán, Río Los Nopales at Las Cruces, 18 º 14 ’ 49.6 ’’ N, 100 º 46 ’ 08.9 ’’ W, 314 m, L- 1496, 28 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♀ UMC); [Mpio. Eduardo Neri], Río Mexcala [Mezcala] 31 mi S of Iguala, 26 - IV- 1964, CL 1040, J. T. & M. S. Polhemus colls. / Ambrysus lunatus lunatus Usinger det. J. T. Polhemus (2 ♂, 1 ♀ SEMC); [Mpio. Eduardo Neri], Río Mexcala [Mezcala] 31 mi S of Iguala, 26 - IV- 1964, CL 1040, J. T. & M. S. Polhemus colls. / C. J. Drake Accession (2 ♂, 6 ♀ USNM); same but / Ambrysus close to sonorensis det. J. T. Polhemus (1 ♂ USNM) [last nine specimens with author’s (DRV) label inaccurately identifying them as A. occidentalis]; Mpio. Teloloapan, [Arroyo El Naranjo] at km 20 carr. Teloloapan-Apaxtla de Castrejón, nr. Tepozanalquillo, 18 º 14 ’ 26.8 ’’ N, 99 º 54 ’ 51 ’’ W, 1083 m, L- 1497, 29 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♀ UMC); Mpio. Teloloapan, Río Oxtotitlán at Oxtotitlán, 18 º 11 ’ 35.7 ’’ N, 99 º 56 ’ 24.3 ’’ W, 1009 m, L- 1498, 29 - XII- 2012, Reynoso-Velasco, D. coll. (3 ♂, 3 ♀ IEXA; 27 ♂, 10 ♀ UMC); Mpio. Tepecoacuilco, [San Agustín] Oapan, 18 º 01 ’ 36.2 ’’ N, 99 º 27 ’ 23.6 ’’ W [wrong GPS data], J. Amith coll. (2 ♂ UMC). Jalisco: Mpio. Atenguillo, El Bajío, km 55 carr. Mascota-Ayutla, ca. 2 km NW of Los Volcanes, 20 ° 20 ’ 08.2 ’’ N, 104 ° 34 ’ 19.2 ’’ W, 1509 m, 27 - VI- 2013, L- 1581, Reynoso-Velasco, D. coll. (3 ♂, 3 ♀ UMC); Mpio. Atenguillo, Río Atenguillo at Los Volcanes, 20 ° 19 ’ 16.5 ’’ N, 104 ° 31 ’ 41.1 ’’ W, 1459 m, 27 - VI- 2013, L- 1582, Reynoso-Velasco, D. coll. (1 ♀ UMC); Mpio. Jalostotitlán, Río Verde at San Nicolás de las Flores on carr. 215 Jalostotitlán-Teocaltiche, 21 ° 17 ’ 32.7 ’’ N, 102 ° 33 ’ 15.4 ’’ W, 1653 m, 28 - VI- 2013, L- 1585, Reynoso-Velasco, D. coll. (18 ♂, 9 ♀ IEXA; 19 ♂, 22 ♀ UMC); [Mpio. La Huerta], Cuitzmala / 20 - III- 1975, H. Brailovsky coll. / Ambrysus hydor 1953 (Ira La Rivers) (1 ♀ CNIN); [Mpio. La Huerta], Estación de Biología Chamela, Cuitzmala, 11 - I- 1975, H. Brailovsky coll. / C. J. Drake Accession (1 ♂ USNM); [Mpio. La Huerta], Estación de Biología Chamela, Río Cuitzmala, 20 - III- 1975 / Ambrysus hydor 1953 (Ira La Rivers) (1 ♀ CNIN); same but Ambrysus hydor La Rivers det. H. Brailovsky A. (1 ♀ CNIN); [Mpio. La Huerta], Río Cuitzmala SE of Chamela, 06 - I- 2005, 180 ’ / William D. Shepard, leg. (1 ♂, 2 ♀ EMEC); Mpio. La Huerta, Río San Nicolás at Pte. San Nicolás, 19 ° 39 ’ 20.8 ’’ N, 105 ° 10 ’ 49.3 ’’ W, 11 m, L- 1574, 25 - VI- 2013, Reynoso-Velasco, D. coll. (1 ♂ IEXA); Mpio. Puerto Vallarta, La Desembocada, 20 ° 43 ’ 36.5 ’’ N, 105 ° 09 ’ 25.7 ’’ W, 39 m, L- 1577, 26 - VI- 2013, Reynoso-Velasco, D. coll. (1 ♀ UMC); Mpio. Puerto Vallarta, Las Palmas de Arriba, 20 ° 49 ’ 31.3 ’’ N, 105 ° 05 ’ 25.3 ’’ W, 120 m, L- 1578, 26 - VI- 2013, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ UMC); Mpio. San Sebastian del Oeste, Arroyo Los Arrayanes at Pte. Los Arrayanes, 20 ° 49 ’ 44.5 ’’ N, 105 ° 00 ’ 45.1 ’’ W, 337 m, L- 1579, 26 - VI- 2013, Reynoso-Velasco, D. coll. (55 ♂, 39 ♀ UMC); Mpio. San Sebastián del Oeste, km 57 carr. [544] San Sebastián-Puerto Vallarta, Ejido Soyután, 20 º 49.899 ’ N, 105 º 00.649 ’ W, 439 m, 09 - IX- 2014, Gómez, Smith & Novelo colls. (1 ♂, 1 ♀ IEXA); Mpio. Tomatlán, Río Tomatlán at Tomatlán, 19 ° 56 ’ 41.4 ’’ N, 105 ° 14 ’ 36.1 ’’ W, 27 m, L- 1575, 25 - VI- 2013, Reynoso-Velasco, D. coll. (4 ♂, 4 ♀ IEXA; 6 ♂, 6 ♀ UMC); [Mpio. Tomatlán], Río Tomatlán 2 mi E of Tomatlán, 03 - III- 1957, M 57 - 19, R. R. & M. Miller & W. P. Hudson (1 ♀ UMMZ); [Mpio. Unión de Tula], Unión de Tula, 16 - IX- [19] 38, H. D. Thomas coll. / Ambrysus scalenus Paratype [incorrect identification] (1 ♂ SEMC). Michoacán: Mpio. Aguililla, Aguililla, 20 - II- 2005, R. Novelo & J. A. Gómez colls. (2 ♂, 3 ♀ IEXA); same but 03 - IV- 2005, R. Novelo coll. (1 ♂, 1 ♀ UMC); same but al sur de Coalcomán, 06 - VI- 2005 (1 ♂, 1 ♀ IEXA); Mpio. Aquila, river at Pte. Ramal Aquila just SW of Aquila, 18 º 35 ’ 08.1 ’’ N, 103 º 30 ’ 51.8 ’’ W, 159 m, L- 1487, 25 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♂ UMC); Mpio. Buenavista, Buenavista Tomatlán, 19 º 12 ’ 57.8 ’’ N, 102 º 34 ’ 30.2 ’’ W, 440 m, 24 - XII- 2012, L- 1481, Reynoso-Velasco, D. coll. (4 ♀ IEXA; 3 ♂, 1 ♀ UMC); Mpio. Carácuaro, Río San Diego at Carácuaro, 19 º 01 ’ 04.8 ’’ N, 101 º 07 ’ 33.2 ’’ W, 519 m, L- 1473, 22 - XII- 2012, Reynoso-Velasco, D. coll. (2 ♂, 2 ♀ IEXA; 4 ♂, 4 ♀ UMC); Mpio. Chinicuila, Villa Victoria (arroyo), 740 m, 17 - V- 2002, R. Novelo coll. (1 ♀ IEXA); Mpio. La Huacana, Colonia Lázaro Cárdenas at La Huacana, 18 º 57 ’ 19 ’’ N, 101 º 48 ’ 43.2 ’’ W, 458 m, L- 1478, 23 - XII- 2012, Reynoso-Velasco, D. coll. (5 ♂, 2 ♀ IEXA; 12 ♂, 3 ♀ UMC); Mpio. Múgica, Pte. El Marquéz 5 km NE of Nueva Italia on carr. 37 Nueva Italia-Uruápan, 13 - III- 2004, R. Novelo coll. (1 ♂ IEXA); Mpio. Múgica, Río Tepalcatepec at Pte. Capiro, km 46 on carr. 37 Apatzingán- Arteaga, 3 km SW of Nuevo Capirio, 14 - IX- 2004, R. Novelo coll. (1 ♀ IEXA); Mpio. Nocupétaro, 4 km NW of Nocupétaro de Morelos, at Pte. Patambo, 19 º 03 ’ 34.6 ’’ N, 101 º 11 ’ 45.4 ’’ W, 622 m, L- 1474, 22 - XII- 2012, Reynoso-Velasco, D. coll. (3 ♂, 2 ♀ IEXA; 8 ♂, 2 ♀ UMC); Mpio. Nocupétaro, San Antonio de la Huerta (Melchor Ocampo), under bridge, 19 º 02 ’ 04.4 ’’ N, 101 º 15 ’ 07.9 ’’ W, 624 m, L- 1475, 22 - XII- 2012, Reynoso-Velasco, D. coll. (2 ♂ IEXA; 5 ♂, 1 ♀ UMC); Mpio. Parácuaro, Crucero Las Yeguas, Río El Orejón at Pte. El Orejón, 12 - III- 2004, R. Novelo coll. (2 ♂, 2 ♀ IEXA); Mpio. Parácuaro, Río Tepalcatepec at Las Yeguas, 18 º 53 ’ 42.1 ’’ N, 102 º 17 ’ 00.3 ’’ W, 189 m, L- 1480, 24 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA; 3 ♂, 4 ♀ UMC); Mpio. Tacámbaro, Rió Frío ca. 18 km E of Tacámbaro, 19 º 12 ’ 50.4 ’’ N, 101 º 20 ’ 47.1 ’’ W, 1297 m, L- 1476, 23 - XII- 2012, Reynoso-Velasco, D. coll. (2 ♂ UMC); Mpio. Tepalcatepec, Los Horcones, Pte. Pinolapa at km 31 carr. Tepalcatepec-Coalcomán, 19 º 00 ’ 31.3 ’’ N, 103 º 01 ’ 25.6 ’’ W, 554 m, L- 1484, 25 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA; 4 ♂, 2 ♀ UMC); Mpio. Tepalcatepec, Río Pinolapa (orilla), 26 - IX- 2005, R. Novelo & J. A. Gómez colls. (2 ♂, 1 ♀ IEXA); Mpio. Tepalcatepec, Río Pinolapa (puente) 2 km SW of Pinolapa, 16 - V- 2002, R. Novelo coll. (2 ♂, 2 ♀ IEXA); same but 28 - III- 2005 (1 ♂ IEXA); same but 10 - VI- 2006 (1 ♂, 3 ♀ IEXA); Mpio. Mpio. Tepalcatepec, Tepalcatepec, 19 º 11 ’ 47.3 ’’ N, 102 º 50 ’ 44.9 ’’ W, 371 m, L- 1483, 24 - XII- 2012, Reynoso-Velasco, D. coll. (2 ♂, 2 ♀ IEXA; 7 ♂, 6 ♀ UMC); Mpio. Tiquicheo, Piedra China, Río Purengueo at Pte. Tiquicheo, 18 º 53 ’ 37.8 ’’ N, 100 º 45 ’ 49 ’’ W, 363 m, L- 1472, 22 - XII- 2012, Reynoso-Velasco, D. coll. (3 ♂, 3 ♀ IEXA; 17 ♂, 10 ♀ UMC); Mpio. Tuzantla, Paso de Tierra Caliente, Las Garzas, 19 º 05 ’ 09.4 ’’ N, 100 º 39 ’ 10.6 ’’ W, 473 m, L- 1471, 22 - XII- 2012, Reynoso-Velasco, D. coll. (4 ♂, 2 ♀ IEXA; 7 ♂, 5 ♀ UMC); Mpio. Tuzantla, Río Tuzantla at Tuzantla, 19 º 13 ’ 18.1 ’’ N, 100 º 34 ’ 05.5 ’’ W, 593 m, L- 1470, 21 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♀ IEXA; 2 ♀ UMC); [Mpio.] Uruapan, El Sabino, 28 - VII- 1936, H. D. Thomas / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); [Mpio.] Uruapan, El Sabino, 28 - VII- 1936, H. D. Thomas / Ambrysus scalenus La Rivers Paratype [incorrect identification] (2 ♂ SEMC); same but / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); Mpio. Zicuirán, Zicuirán, 18 º 53 ’ 01.4 ’’ N, 101 º 58 ’ 34.3 ’’ W, 216 m, L- 1479, 23 - XII- 2012, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ UMC). Morelos: [Mpio. Amacuzac], Río Amacuzac [at] Huajintlán, 28 - V- 1983, D. Porras & L. Castrejón colls. / Colección del Instituto de Biología, UNAM, México D. F. (2 ♂, 3 ♀ CNIN); same but / Naucoridae Ambrysus sp. / C. J. Drake Accession (3 ♂, 1 ♀ USNM); Mpio. Amacuzac, Río Amacuzac at Pte. Huajintlán on carr. libre Cuernacava- Taxco, 18 º 36 ’ 35.56 ’’ N, 99 º 25 ’ 40.38 ’’ W, 931 m, 04 - I- 2017, L- 1989, Reynoso-Velasco coll. (22 ♂, 23 ♀ IEXA); Mpio. Amacuzac, Río Amacuzac at 1.6 km on dirt road S of km 50 carr. Cuernavaca-Taxco, 18 º 35 ’ 48.05 ’’ N, 99 º 23 ’ 57.88 ’’ W, 917 m, 04 - I- 2017, L- 1990, Reynoso-Velasco coll. (7 ♂, 5 ♀ IEXA); [Mpio. Amacuzac], 4 mi N of Amacuzac, CL 1039, 25 Apr. 1964, J. T. & M. S. Polhemus colls. / C. J. Drake Accession (4 ♂, 4 ♀ USNM) [all eight specimens with author’s label inaccurately identifying them as A. occidentalis]; [Mpio. Cuernavaca], Cuernavaca, VI- 1943 / H. E. Hinton coll. (1 ♂ EMEC); Mpio. Jojutla, Río Amacuzac at San Rafael Vicente Aranda, 04 - IV- 2002, R. Novelo coll. (4 ♂, 4 ♀ IEXA); same but 900 m, 16 - III- 2001 (1 ♂, 4 ♀ IEXA); Mpio. Jojutla, Río Amacuzac at Tehuixtla, 18 º 33 ’ 45.2 ’’ N, 99 º 16 ’ 51.3 ’’ W, 853 m, 28 - IV- 2011, L- 1308, Reynoso-Velasco, D. coll. (2 ♂, 3 ♀ IEXA; 8 ♂, 14 ♀ UMC); same but 18 º 33 ’ 41.8 ’’ N, 99 º 16 ’ 46.1 ’’ W, 856 m, 31 - XII- 2012, L- 1502 (2 ♀ UMC); Mpio. Jojutla, [San Rafael] V [icente] Aranda, Río Amacuzac, 15 - I- 1983, V. García coll. (2 ♂, 2 ♀ UMC); Mpio. Jojutla, Tehuixtla, Río Amacuzac at Pte. ISSSTEHUIXTLA, 18 º 32 ’ 47.9 ’’ N, 99 º 16 ’ 03.6 ’’ W, 854 m, 28 - IV- 2011, L- 1309, Reynoso-Velasco, D. coll. (10 ♂, 1 ♀ UMC); Mpio. Jonacatepec, estanque en Jonacatepec, 06 - X- 2001, R. Novelo coll. (1 ♂ IEXA); Mpio. Tlaquiltenango, El Astillero [also La Mezquitera], Río Cuautla, 850 m, 05 - II- 1983, I. Olivia coll., en orillas c / vegetación (4 ♂, 4 ♀ IEXA); Mpio. Yautepec, Oacalco (arroyo), 03 - IV- 2002, R. Novelo col. (2 ♀ IEXA); Mpio. Yautepec, Río Yautepec at Itzamatitlán, 17 - III- 2001, R. Novelo coll. (1 ♀ IEXA); 20 mi S of Cuernavaca, CL 1047, 27 Apr. 1964, J. T. & M. S. Polhemus colls. / C. J. Drake Accession (1 ♂, 1 ♀ USNM) [both specimens with author’s label inaccurately identifying them as A. occidentalis]. Nayarit: [Arroyo Refilión 29 km S of Tepic, at], El Refilio [Refilión], 2800 ’, CL 729, 08 - VI- 1975, J. T. Polhemus coll. (1 ♂, 1 ♀ USNM); same but / C. J. Drake Accession (1 ♂ USNM); [last three specimens with author’s label inaccurately identifying them as A. occidentalis]; Mpio. Acaponeta, Río Acaponeta at El Recodo, 22 ° 31 ’ 31.9 ’’ N, 105 ° 20 ’ 37.3 ’’ W, 34 m, 01 - VII- 2013, L- 1601, Reynoso-Velasco, D. coll. (1 ♂, 3 ♀ IEXA; 7 ♂, 6 ♀ UMC); Mpio. Acaponeta, Río Acaponeta at La Guásima, 22 ° 24 ’ 26.6 ’’ N, 105 ° 23 ’ 48.9 ’’ W, 26 m, 02 - VII- 2013, L- 1602, Reynoso-Velasco, D. coll. (1 ♂ UMC); Mpio. Acaponeta, Río Las Cañas at La Bayona, 22 ° 31 ’ 15.8 ’’ N, 105 ° 26 ’ 44.4 ’’ W, 20 m, 01 - VII- 2013, L- 1600, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA; 2 ♂, 7 ♀ UMC); [Mpio. Ahuacatlán], Ahuacatlán, 12 - VIII- 1957, D. R. Lauck coll. / Ambrysus magniceps La Rivers 1953 (La Rivers) / C. J. Drake Accession (1 ♂, 1 ♀ USNM) [both specimens with author’s label inaccurately identifying them as A. occidentalis]; Mpio. Compostela, Las Piedras, Pte. Las Piedras, Río Las Piedras, 21 ° 12 ’ 08.7 ’’ N, 105 ° 05 ’ 31.8 ’’ W, 69 m, L- 1654, 19 - XII- 2013, Reynoso-Velasco, D. coll. (7 ♂, 10 ♀ IEXA); Mpio. Compostela, Las Varas, Pte. Arroyo Seco, 21 ° 11 ’ 15.2 ’’ N, 105 ° 07 ’ 21.7 ’’ W, 39 m, L- 1655, 19 - XII- 2013, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA); Mpio. Compostela, Río Compostela at Compostela, 21 ° 14 ’ 01.4 ’’ N, 104 ° 53 ’ 38.6 ’’ W, 853 m, L- 1652, 18 - XII- 2013, Reynoso-Velasco, D. coll. (6 ♂, 8 ♀ IEXA); same but 21 ° 14 ’ 01.4 ’’ N, 104 ° 54 ’ 22.9 ’’ W, 840 m, L- 1653 (1 ♀ IEXA); Mpio. Compostela, Río Huicila at Zacualpan, 21 ° 15 ’ 04.1 ’’ N, 105 ° 09 ’ 30.6 ’’ W, 20 m, 19 - XII- 2013, L- 1656, Reynoso-Velasco, D. coll. (1 ♂ IEXA); [Mpio. Del Nayar], Jesús María, 26 - VI- 1955 / B. Malkin coll. (2 ♂, 3 ♀ EMEC); [Mpio. Del Nayar], Mesa del Nayar, 16 – 21 - VII- [19] 55, B. Malkin coll. (5 ♂ EMEC); [Mpio. Del Nayar], Playa de Golondrinas, Río Santiago, 27 - V- 1992, J. Bueno & R. Barba (8 ♂, 6 ♀ CNIN); [Mpio. Del Nayar], San Juan Peyotán, 01 - VIII- [19] 55, B. Malkin coll. (1 ♂, 3 ♀ EMEC); Mpio. Ruíz, Río San Pedro at Lomas de San Isidro, 3 km W of Vado San Pedro, 21 ° 56 ’ 44.5 ’’ N, 105 ° 12 ’ 42.4 ’’ W, 14 m, 02 - VII- 2013, L- 1603, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA; 1 ♂, 4 ♀ UMC); Mpio. Ruíz, Río San Pedro at San Lorenzo, 21 ° 57 ’ 04.1 ’’ N, 105 ° 04 ’ 28.3 ’’ W, 23 m, L- 1662, 20 - XII- 2013, Reynoso-Velasco, D. coll. (8 ♂, 3 ♀ IEXA); Mpio. Ruíz, Río San Pedro at Vado San Pedro, 21 ° 57 ’ 01.7 ’’ N, 105 ° 10 ’ 45.0 ’’ W, 13 m, 02 - VII- 2013, L- 1604, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ UMC); [Mpio. San Blas], Aticama, CL 727 A, 07 - VI- 1975, J. T. Polhemus coll. / C. J. Drake Accession (5 ♂, 11 ♀ USNM); same but same but A. sonorensis? Usinger J. T. P. ‘ 99 (1 ♂ USNM) [all 17 specimens with author’s label inaccurately identifying them as A. occidentalis]; Mpio. San Blas, El Palillo, Arroyo Palillo at Pte. Palillo, 21 ° 38 ’ 27.1 ’’ N, 105 ° 08 ’ 30.8 ’’ W, 43 m, L- 1661, 20 - XII- 2013, Reynoso-Velasco, D. coll. (52 ♂, 22 ♀ IEXA); [Mpio. San Blas], Navarrette [Navarrete], 01 - VII- [19] 62 / A. E. Michelbacher coll. (1 ♂ EMEC); [Mpio. Santa Cruz de Miramar], Santa Cruz, 08 - VI- 1975, CL 728, J. T. Polhemus coll. / C. J. Drake Accession (1 ♂ USNM) [specimen with author’s label inaccurately identifying them as A. occidentalis]; Mpio. Santa María del Oro, El Ocotillo, 21 ° 13 ’ 46.4 ’’ N, 104 ° 38 ’ 29.8 ’’ W, 1176 m, 02 - VII- 2013, L- 1605 Reynoso-Velasco, D. coll. (7 ♂, 8 ♀ IEXA; 13 ♂, 15 ♀ UMC). Oaxaca: Mpio. SanAntonio Nanahuatípam, Río Salado at SanAntonio Nanahuatípam, 18 ° 07 ’ 59.4 ’’ N, 97 ° 07 ’ 42.6 ’’ W, 790 m, L- 1877, 24 - III- 2015, Reynoso, Sites, Shepard & Barr colls. (1 ♂, 3 ♀ IEXA); Mpio. San Sebastian Tecomaxtlahuaca, Tecomaxtlahuaca, Laguna Encantada, 17 º 21 ’ 57.5 ’’ N, 98 º 01 ’ 13.3 ’’ W, 1662 m, 30 - V- 2012, L- 1399, Reynoso-Velasco, D. coll. (2 ♀ UMC). Puebla: Matamoros, 12 mi SE Puebla, 03 - VII- 1953, 3700 ft / Univ. Kans. Mex. Expedition / Slesnick Field No. 31 / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂, 1 ♀, 1 indt. CAS); Mpio. Coxcatlán, [Río Tepazalco at] La Estación, 5 Km SW of Coxcatlán, 18 ° 15 ’ 07.3 ’’ N, 97 ° 11 ’ 24.5 ’’ W, 950 m, 24 - III- 2015, L- 1876, Reynoso Sites, Shepard & Barr colls. (1 ♀ IEXA); Mpio. Jolalpan, Río Nexapa at Jolalpan, 18 º 20 ’ 58.4 ’’ N, 98 º 49 ’ 18.2 ’’ W, 841 m, 30 - XII- 2012, L- 1501, Reynoso-Velasco, D. coll. (2 ♂, 1 ♀ IEXA; 7 ♂, 1 ♀ UMC); [Mpio. Puebla], Puebla, 26 - VI- 1957, D. Lauck coll. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂, 2 ♀ CAS); [Mpio. Tehuitzingo], El Marquez, [Río Balsas / Atoyac at Puente El Marqués], CL 1052, 28 - IV 1964, J. T. & M. S. Polhemus colls. / Ambrysus lundbladi Us. det. J. T. Polhemus / C. J. Drake Accession (1 ♀ USNM) [specimen with author’s label inaccurately identifying them as A. occidentalis]; [Mpio. Tehuitzingo], Tehuitzingo, 10 mi SE Puebla, 03 - VII- 1953, 3900 ft / Univ. Kans. Mex. Expedition / Slesnick Field No. 32 / Ambrysus scalenus La Rivers 1953 (Ira La Rivers) (1 ♂ SEMC); same but / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); [Mpio Teziutlán], Teziutlán, 27 - VII- 1950, Drake & Hottes colls. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (2 ♀ CAS). Sinaloa: [Mpio. Badiraguato], Río Badiraguato just upstream from village of Badiraguato, 06 - III- 1961, M 61 - 15, R. R. Miller & H. L. Huddle colls. (1 ♂ UMMZ); [Mpio. Concordia], Arroyo El Zapotillo [at] 2 mi E of Concordia, 20 - VII- 1952, J. D. Lattin coll. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (8 ♂, 4 ♀ CAS); [Mpio. Concordia], Concordia, 20 - VII- 1952, J. D. Lattini coll. / more in alcohol / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); Mpio. Concordia, Río Pánuco at Chupaderos, 23 ° 21 ’ 49.2 ’’ N, 105 ° 57 ’ 10.3 ’’ W, 244 m, L- 1597, 30 - VI- 2013, Reynoso-Velasco, D. coll. (6 ♂, 6 ♀ UMC); Mpio. Cosalá, Río Conitaca ca. 27 km S of Cosalá, 24 ° 13 ’ 26.6 ’’ N, 106 ° 44 ’ 37.9 ’’ W, 169 m, L- 1671, 22 - XII- 2013, Reynoso-Velasco, D. coll. (4 ♂, 4 ♀ IEXA); [Mpio. Culiacán], Culiacán, Río Culiacán / 25 - VII- 1952 / lunatus? / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); [Mpio. Culiacán], Los Mayos, 24 - VII- 1952, J. D. Lattin coll., Cal. Acad. Sci. Coll. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♂, 1 ♀ CAS); same but / lunatus? (1 ♂ CAS); Mpio. Elota, Arroyo El Japuino at Pte. Los Barriles, 24 ° 03 ’ 36.7 ’’ N, 106 ° 48 ’ 03.6 ’’ W, 83 m, 22 - XII- 2013, L- 1670, Reynoso-Velasco, D. coll. (2 ♀ IEXA); Mpio. Elota, Río Elota at Pte. Río Elota, 23 ° 57 ’ 20.7 ’’ N, 106 ° 42 ’ 53.4 ’’ W, 46 m, L- 1669, 22 - XII- 2013, Reynoso-Velasco, D. coll. (16 ♂, 12 ♀ IEXA); Mpio. Guasave, Río Sinaloa at Estación Bamoa, 25 ° 42 ’ 34.9 ’’ N, 108 ° 20 ’ 31.6 ’’ W, 24 m, 23 - XII- 2013, L- 1675, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA); [Mpio. Mazatlán], Mazatlán, 1934 / H. E. Hinton coll. (5 ♂, 1 ♀ EMEC); / Ira La Rivers Collection Bequeathed to the California Academy of Sciences (1 ♂, 1 ♀ CAS); [Mpio. Maztlán], Mazatlán, 25 – 26 - V- 1934 / H. E. Hinton coll. (2 ♂, 2 ♀ EMEC); same but / Ira La Rivers Collection Bequeathed to the California Academy of Sciences (1 ♀ CAS); same but / Ambrysus hydor La Rivers Paratype / an unpublished paratype det. [in] 1970 by Vincent F. Lee (1 ♂ CAS) [locality not reported in the original description]; Mpio. Mazatlán, Río Presidio at Siqueiros, 23 ° 20 ’ 47.0 ’’ N, 106 ° 14 ’ 35.3 ’’ W, 42 m, L- 1664, 21 - XII- 2013, Reynoso-Velasco, D. coll. (4 ♂, 4 ♀ IEXA); Mpio. Mazatlán, Río Quelite at Pte. El Quelite, 23 ° 31 ’ 19.5 ’’ N, 106 ° 29 ’ 52.9 ’’ W, 12 m, L- 1665, 21 - XII- 2013, Reynoso-Velasco, D. coll. (18 ♂, 20 ♀ IEXA); Mpio. Mazatlán, Villa Unión, Río Presidio at Pte. Presidio, 23 ° 11 ’ 32.3 ’’ N, 106 ° 13 ’ 26.3 ’’ W, 10 m, L- 1598, 01 - VII- 2013, Reynoso-Velasco, D. coll. (18 ♂, 10 ♀ IEXA; 11 ♂, 11 ♀ UMC); [Mpio. Mazatlán], 28 mi N [of] Mazatlán, 23 - VII- 1967 / M. Wasbauer coll. (1 ♀ CSCA); Mpio. Mocorito, Rancho Viejo, Pte. Chico Ruíz, 25 ° 07 ’ 24 ’’ N, 107 ° 45 ’ 29.9 ’’ W, 59 m, L- 1673, 23 - XII- 2013, Reynoso-Velasco, D. coll. (1 ♂ IEXA); Mpio. Mocorito, Río Evora at Mocorito, 25 ° 28 ’ 55.1 ’’ N, 107 ° 54 ’ 37.6 ’’ W, 75 m, L- 1674, 23 - XII- 2013, Reynoso-Velasco, D. coll. (2 ♀ IEXA); Mpio. Rosarío, Río Baluarte at Pte. Baluarte, 23 ° 00 ’ 26.0 ’’ N, 105 ° 51 ’ 04.5 ’’ W, 24 m, 01 - VII- 2013, L- 1599, Reynoso-Velasco, D. coll. (3 ♂, 1 ♀ UMC); Mpio. Rosario, Río Los Cedros at Matatán, 16 km W of El Rosario, 23 ° 01 ’ 54.1 ’’ N, 105 ° 43 ’ 52.0 ’’ W, 55 m, L- 1663, 21 - XII- 2013, Reynoso-Velasco, D. coll. (3 ♂, 5 ♀ IEXA); [Mpio. Salvador Alvarado], Río Mocrito [Mocorito] just NW of Huamichie [Guamúchil], 03 - II- 1955, M 55 - 4, Miller & Greenbank colls. (8 ♂, 5 ♀ UMMZ); Mpio. San Ignacio, Río Piaxtla at San Ignacio, 23 ° 56 ’ 06.3 ’’ N, 106 ° 25 ’ 41.0 ’’ W, 127 m, L- 1666, 21 - XII- 2013, Reynoso-Velasco, D. coll. (25 ♂, 28 ♀ IEXA); same but 23 ° 56 ’ 11.9 ’’ N, 106 ° 25 ’ 34.0 ’’ W, 134 m, L- 1667, 22 - XII- 2013 (20 ♂, 55 ♀ IEXA); Mpio. San Ignacio, Río Piaxtla at Pte. Río Piaxtla, 23 ° 53 ’ 23.8 ’’ N, 106 ° 37 ’ 03.9 ’’ W, 46 m, L- 1668, 22 - XII- 2013, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA); Mpio. Sinaloa de Leyva, Arroyo Bacubirito at Bacubirito, 25 ° 48 ’ 21.4 ’’ N, 107 ° 54 ’ 48.5 ’’ W, 159 m, L- 1677, 24 - XII- 2013, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA); [Mpio. Sinaloa de Leyva], Río Bacubirito near Bacubirito, 04 - III- 1962, M 61 - 12, R. R. Miller & H. L. Huddle colls. (1 ♀ UMMZ); Mpio. Sinaloa de Leyva, Río Sinaloa at Burague, 25 ° 49 ’ 25.4 ’’ N, 107 ° 57 ’ 49.4 ’’ W, 140 m, L- 1678, 24 - XII- 2013, Reynoso-Velasco, D. coll. (4 ♂, 5 ♀ IEXA); Mpio. Sinaloa de Leyva, Río Sinaloa at El Cajoncito, 25 ° 52 ’ 41.1 ’’ N, 107 ° 56 ’ 50.8 ’’ W, 119 m, 23 - XII- 2013, L- 1676, Reynoso-Velasco, D. coll. (1 ♂ IEXA). Sonora: [Mpio. Álamos], Álamos, 29 - VII- 1953, F. S. Truxal coll. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (1 ♀ UMC); same but 25 - VII – 07 - VIII- 1953 / Ambrysus hydor La Rivers 1953 (Ira La Rivers) (2 ♀ CAS); [Mpio. Álamos], Río Chuchuhaqui [Chuchujaqui] 7 mi S [of] Álamos, 25 - VII – 07 - VIII- 1953, Fred. S. Truxal coll. / Ambrysus hydor La Rivers 1953 (Ira La Rivers) / Ira La Rivers Collection Bequeathed to the California Academy of Sciences - 1978 (2 ♀ CAS).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	description	(Figs. 15 – 16) Ambrysus inecol Reynoso in Reynoso-Velasco 2023: Zootaxa, 5271: 561 – 565 (original description).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	diagnosis	Diagnosis. This species can be distinguished from others in the section by the almost symmetrical and tapering female SGP with right-angled lateral lobes at mid-length of each margin; the lobe on the right margin is only slightly smaller. Additionally, the posterolateral corners are short and pointed and the central lobe is poorly developed and shallowly concave medially, giving the appearance of two rounded lobes (Fig. 15 B). Also, the male phallosoma presents the endosoma apically sclerotized on the left side (Fig. 15 E black arrow) and both endosomal sclerites knob-like with inconspicuous denticles (Fig. 15 E). Comparative notes. Ambrysus inecol is overall similar to A. magniceps; nevertheless, females of A. inecol exhibit a characteristic SGP that tapers apically, the width of the posterior margin is approximately 1 / 3 of the SGP’s maximum width, which contrasts with the approximately 2 / 3 in A. magniceps. Also, the SGP central lobe of A. inecol is shallowly concave medially, giving the appearance of two rounded lobes at the same level or only slightly below the level of the posterolateral corners, whereas the central lobe in A. magniceps is evenly convex (without a medial concavity) and slightly beyond the level of the posterolateral corners. The digitate shape of the sclerotized male endosoma is also more similar to that of A. magniceps because the structure is lobe-shaped in A. altiplanus.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	discussion	Discussion. This species measures 11.50 – 13.50 in length and 6.75 – 8.13 in width. The shapes of the male accessory process, pseudoparameres, and sclerotized endosoma of A. inecol are similar to those of A. altiplanus and A. magniceps, which we consider as evidence of a close relatedness. The shape of the pseudoparameres and characteristics of the phallosoma in males, as well as a compact, oval, and particular convex body shape were features used to conceptualize A. magniceps (Reynoso-Velasco 2023). This conception resulted in the overlooking of variation in the shape of the female SGP (informative attribute for species identification in the genus Ambrysus), which was the basis to describe A. inecol. Some specimens from western Mexico deposited in various collections (e. g., CAS, USNM) where identified by DRV as A. magniceps; however, the concept of the species has changed after the description of A inecol. Consequently, further examination is necessary to clearly establish whether those specimens belong to A. magniceps or A. inecol. These specimens were not included in this study.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	description	Variation. Some females presented the SGP with a central lobe only shallowly concave medially. Additionally, a female from Jalisco (Cabo Corrientes) and that from Michoacán exhibited the central lobe evenly rounded.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	materials_examined	Type locality. Mexico: Nayarit: Mpio. Ahuacatlán, Río Tetitlán at Puerta del Río (Balneario El Paraiso), 21 ° 10 ’ 59.3 ’’ N, 104 ° 38 ’ 32.9 ’’ W. Repository. Female holotype (Fig. 15 A) is housed at the IEXA. Published records. MEXICO: Nayarit, Jalisco, Michoacán (Reynoso Velasco 2023).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	distribution	Distribution. Ambrysus inecol exhibits a neotropical distribution in west-central Mexico, in the states of Jalisco, Michoacán, and Nayarit (Fig. 16). Most of the localities where the species has been recorded are on the border of the Pacific Lowlands and the westernmost and northwesternmost sections of the Transmexican Volcanic Belt (Nayarit) and Sierra Madre del Sur (Jalisco) biogeographic provinces, respectively. Only the record from Michoacán is on the border of the Balsas Basin and Transmexican Volcanic Belt biogeographic provinces. All the localities are at elevations below 1,000 meters.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB15FFF9FF71F9CCAAFA5709.taxon	materials_examined	Type material examined. HOLOTYPE ♀. MEXICO: Nayarit: Mpio. Ahuacatlán, Río Tetitlán at Puerta del Río (Balneario El Paraiso), 21 ° 10 ’ 59.3 ’’ N, 104 ° 38 ’ 32.9 ’’ W, 859 m, 18 - XII- 2013, L- 1651, Reynoso-Velasco, D. coll. PARATYPES: same data as holotype (1 ♀ CNIN; 2 ♂, 3 ♀ IEXA; 1 ♂, 1 ♀ UMC); Mpio. Compostela, Río Compostela at Compostela, 21 ° 14 ’ 01.4 ’’ N, 104 ° 53 ’ 38.6 ’’ W, 853 m, 18 - XII- 2013, L- 1652, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA); [Mpio. Compostela, Río El Refilión at] puente El Refilión on carr. Nayarit-Compostela, [21 ° 18 ’ 19.9 ’’ N, 104 ° 54 ’ 29.1 ’’ W, 790 m], 26 - X- 1989, A. Cadena coll. (1 ♀ CNIN). Jalisco: Mpio. Cabo Corrientes, arroyo at puente Horcones, 20 ° 27.548 N, 105 ° 17.519 W, 330 m, 19 - III- 2014, J. A. Gómez, S. Smith & R. Novelo colls. (6 ♂, 2 ♀ IEXA); Mpio. San Sebastián del Oeste, arroyo at km 52 + 800 on carr. 544 Potrero de Arriba-Palmillas de Macedo, 481 m, 20 ° 49.015 N, 104 ° 58.811 W, 06 - IX- 2014, J. A. Gómez, S. Smith & R. Novelo colls. (1 ♀ IEXA). Michoacán: Mpio. Buenavista, river at Buenavista Tomatlán, 19 º 12 ’ 57.8 ’’ N, 102 º 34 ’ 30.2 ’’ W, 440 m, 24 - XII- 2012, L- 1481, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ IEXA).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	description	(Figs. 17 – 19)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 20 degrees close to proximal third, angled again at approximately 80 degrees at distal third (Fig. 17 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral and posteromesal corners broadly rounded, posterior margin shallowly concave medially (Fig. 17 D). Phallosoma elongate, linear, slender, tapering dorsoapically; endosoma lightly sclerotized apically on left side, digitate (Fig. 17 E black arrow); endosomal sclerites knob-like, with inconspicuous denticles (Fig. 17 E). Parameres symmetrical, slightly longer than maximum width, mesal margin convex. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 17 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	diagnosis	Diagnosis. This species can be distinguished from other species in the section by the symmetrical SGP with right-angled to pointed lateral lobes slightly posterior to mid-length of each margin. Additionally, the posterolateral corners are small and rounded and the central lobe is evenly rounded. The male phallosoma presents the endosoma apically sclerotized on the left side and both endosomal sclerites are knob-like with inconspicuous denticles (Fig. 17 E). Comparative notes. This species has a close resemblance to A. inecol but with important differences that clearly identify them as distinct species (see Comparative notes in treatment of A. inecol).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	discussion	Discussion. This species measures 10.87 – 13.00 in length and 6.62 – 7.75 in width. A close relationship of this species and A. altiplanus was supported based on molecular data recently presented by Sites (2022). See Discussion section in treatment of A. inecol for the reason to refrain from reporting some specimens in various collections initially identified by DRV as belonging to A. magniceps.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	description	Variation. Some females exhibit the SGP with posterolateral corners poorly developed and inconspicuous; thus, the posterior margin is evenly rounded. Also, the central lobe can be indistinctly concave medially. Additionally, in some females the lateral lobe on the right margin of the SGP is slightly smaller, giving the plate an asymmetrical appearance.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	materials_examined	Type locality. Mexico: Estado de México: Mpio. Tejupilco, Tejupilco. Repository. Male holotype (Fig. 18 A) is housed at the CAS. Published records: Mexico: Estado de México (La Rivers 1953 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	description	New records: MEXICO: Guerrero, Michoacán, Oaxaca.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	distribution	Distribution. Ambrysus magniceps is distributed in central and southwestern Mexico (Fig. 19) at elevations of 600 – 1,300 meters. The species was previously known from only the type locality in central Mexico (Estado de México). This locality is in the Balsas Basin biogeographic province, whereas the new reports from the western part of the country are on the border between the Sierra Madre del Sur province and the southern section of the Pacific Lowlands province.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB10FFC6FF71FEB0AB6554BD.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). MEXICO: Estado de México: [Mpio. Tejupilco], Tejupilco, Temescaltepec [District of Temascaltepec], 19 - VI- [19] 33 / H. E. Hinton & R. L. Usinger colls. / Ambrysus magniceps La Rivers HOLOTYPE / Ambrysus magniceps La Rivers determined by Ira La Rivers 1948 / California Academy of Sciences Type No. 10057. PARATYPES: same data as holotype but 15 - VI- [19] 33 / Ambrysus magniceps La Rivers ALLOTYPE / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); same but Paratype Ambrysus magniceps La Rivers Det. 1978 by Vincent F. Lee / “ We have the allotype in the type collection, ” 06 - XII- 78 V. F. Lee (1 ♀ CAS); [Mpio. Tejupilco], Tejupilco, Temescaltepec [District of Temascaltepec], 15 - VI- [19] 33 / H. E. Hinton & R. L. Usinger colls. / Ambrysus magniceps La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); same but / 97 (1 ♂ CAS). Additional material examined. MEXICO: Guerrero: [Mpio. Chilpancingo de Los Bravo, Zoyatepec River at] Soyatepec [Zoyatepec, approx. 17 º 19 ’ 43.8 ’’ N, 99 º 33 ’ 37.4 ’’ W, 730 m], 25 - VI- 1983, M. García coll. (1 ♀ CNIN). Michoacán: Mpio. Chinicuila, Villa Victoria, 750 m, 10 - VIII- 2000, Novelo, R. coll. (1 ♂, 1 ♀ IEXA); same but arroyo en Villa Victoria, 740 m, 17 - V- 2002, Novelo, R. coll. (2 ♂, 1 ♀ IEXA); Mpio. Chinicuila, Villa Victoria, 700 m, 31 - III- 2005, Novelo, R. coll. (4 ♂ IEXA); same but 03 - VI- 2005 (1 ♂ IEXA); same but 10 - I- 2006 (1 ♀ IEXA); Mpio. Coalcomán, El Salitre de Maruata, 18 º 53 ’ 00.6 ’’ N, 103 º 08 ’ 40.5 ’’ W, 1149 m, L- 1485, 25 - XII- 2012, Reynoso-Velasco, D. coll. (8 ♂, 9 ♀ IEXA); Mpio. Coalcomán, Río El Gauyabal at El Salitre de Maruata, 18 º 52 ’ 50.4 ’’ N, 103 º 08 ’ 44.5 ’’ W, 1143 m, 25 - XII- 2012, L- 1486, Reynoso-Velasco, D. coll. (1 ♂, 2 ♀ IEXA); Mpio. Coalcomán, La Chichihua, 10 - II- 2005, Novelo, R & Gómez-Anaya, J. colls (1 ♂ IEXA); same but S [ierra] de Coalcomán, 04 - VI- 2005, Novelo, R. coll. (2 ♂, 1 ♀ IEXA); same but 10 - VII- 2005 (1 ♂ IEXA). Oaxaca: Mpio. Putla Villa de Guerrero, stream at Pluta de Guerrero, 17 º 02 ’ 21.5 ’’ N, 97 º 54 ’ 42.9 ’’ W, 767 m, 30 - V- 2012, L- 1397, Reynoso-Velasco, D. coll. (1 ♂ IEXA); [Mpio. San Gabriel Mixtepec], San Gabriel Mixtepec, 20 - V- 1984, H. Velazco coll. (1 ♂ CNIN); Mpio. San Gabriel Mixtepec, km 194 carr. Puerto Escondido-Oaxaca, San Gabriel Mixtepec, Río Rana, 16 º 06 ’ 06.3 ’’ N, 97 º 03 ’ 52.9 ’’ W, 712 m, 27 - V- 2012, L- 1380, Reynoso-Velasco, D. coll. (1 ♂, 3 ♀ IEXA); same but 03 - IV- 2015, L- 1906, Reynoso, Sites, Shepard & Barr colls. (2 ♂, 2 ♀ IEXA).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	description	(Figs. 20 – 22)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 50 degrees at proximal third, angled again at approximately 80 degrees at distal fifth (Fig. 20 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral corner narrowly rounded, posteromesal corner broadly rounded, posterior margin almost straight (Fig. 20 D). Phallosoma elongate, linear, slender, tapering dorsoapically; endosomal sclerites knob-like, right-tilted, with conspicuous denticles (Fig. 20 E). Parameres symmetrical, slightly longer than maximum width, mesal margin convex. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 20 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	diagnosis	Diagnosis. This species can be distinguished from other species in the section by the symmetrical SGP with small, rounded lateral lobes at mid-length of each margin. Additionally, the posterolateral corners are small and rounded and the central lobe is poorly developed and shallowly concave medially (Fig. 20 B). Also, the male phallosoma presents both endosomal sclerites knob-like with robust denticles. It is common that both, or at least the left endosomal sclerite, are tilted to the right (Fig. 20 E). Comparative notes. See corresponding section in treatment of A. hydor. Additionally, another important aid to distinguish between the alike A. occidentalis and A. hydor is that the former species generally exhibits the phallosoma with both endosomal sclerites, or at least that on the left, tilted to the right. These sclerites are generally straight and basally directed in A. hydor. In general, the endosomal sclerites of A. occidentalis exhibit robust denticles, whereas A. hydor has small denticles.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	discussion	Discussion. This species measures 11.00 – 12.75 in length and 7.25 – 8.37 in width. In the original description, La Rivers (1951) reported material of this species from Baja California and Sonora, in northwestern Mexico; however, A. occidentalis was not included in the study on the Ambrysus of Mexico (La Rivers 1953 a). Additionally, as mentioned by La Rivers (1951: 325) and confirmed here, early reports of A. signoreti in the United States (e. g., some specimens from Arizona and California in the Material examined section) were sometimes based on misidentified specimens belonging to A. occidentalis. See Discussion section in treatment of A. hydor for the reason to refrain from reporting some specimens in various collections (e. g., CAS, USNM) initially identified by DRV as belonging to A. occidentalis.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	description	Variation. Some females exhibit the SGP with the lateral lobes right-angled. Sometimes, the posterolateral corners are slightly pointed. Also, females can present an asymmetrical SGP, with a slightly smaller lateral lobe on the right margin. Additionally, the commonly tilted-to-the-right left endosomal sclerite in the phallosoma of the males can be mesally directed and perpendicular to the right sclerite.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	materials_examined	Type locality. United States of America: Arizona: Cochise County. La Rivers (1951: 324) originally reported the type locality as only Cochise County and stated: “ no specific locality is given on the collecting labels, but since this is the largest and most representative series available, and Cochise County is not a very large area, no real problems are likely to result from this omission. ” On the next page of the same work, in the Material examined section, La Rivers (1951: 325) reported the specific location “ San Bernardino Ranch (3,750 ft) ” as the type locality of A. occidentalis. This was most likely because San Bernardino Ranch was the sole specific locality on data labels of specimens from Cochise County in the type series. Repository. Male holotype (Fig. 21 A) is housed at the SEMC.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	description	Published records: MEXICO: Baja California, Sinaloa, Sonora; UNITED STATES: Arizona, California (La Rivers 1951, 1958; Davis 1986; Reynoso-Velasco & Sites 2019 b). The record from Sinaloa (Davis 1986) was based on a single male from the southern part of the state, which was not examined during this study. The southern location (east of Concordia) of this record and the current concept of the species suggests this specimen could belong to A. hydor, which is commonly found throughout Sinaloa; thus, further examination of the specimen is necessary to clarify its identity. This record is not included in the distribution map. New record: Mexico: Chihuahua.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	distribution	Distribution. Ambrysus occidentalis is distributed in extreme northwestern Mexico and southwestern United States (Fig. 22) at elevations below 1,800 meters. In Mexico, the species is present in at least four biogeographic provinces: Baja California (in the homonymous state), northernmost section of the Pacific Lowlands (Sinaloa, Sonora) and Sierra Madre Occidental (Chihuahua, Sonora), and the northwesternmost section of the Chihuahuan Desert (Chihuahua). In the United States, A. occidentalis is distributed southwest of the Colorado Plateau, in at least three other physiographic provinces: southwestern section of the Basin and Range (Arizona, California), southernmost section of the Pacific Border (California), and the small area of the Lower California province (California). The arched distribution pattern of the species, with scarcely any records in the area encompassing western Sonora and northeastern Baja California in Mexico and southeastern Arizona and southwestern California in the United States, is most probably due to the dry conditions present in the Sonoran Desert.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB2FFFC2FF71FD24AA2651C9.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). UNITED STATES: Arizona: Cochise Co., 29 - VII- 1927, P. A. Readio [R. H. Beamer was reported in the original description] / Ambrysus occidentalis La Rivers HOLOTYPE / Ambrysus occidentalis La Rivers determined by Ira La Rivers 1948. PARATYPES: same data as holotype but R. H. Beamer coll. (2 ♂, 2 ♀ SEMC). California: [San Diego Co.], Miramar, 28 - VII- [19] 38, R. I. Sailer coll. / Ambrysus occidentalis La Rivers Paratype (1 ♀ UMC). MEXICO: Sonora: Álamos, Palmer District, 27 - X- 1934, H. S. Gentry / Ambrysus occidentalis La Rivers Paratype (1 ♀ SEMC). Additional material examined. MEXICO: Baja California: Ensenada Lake, 19 - VII- [19] 24, W. Benedict / Ambrysus occidentalis La Rivers Paratype (1 ♂ UMC) [an unpublished paratype]; [Mpio. Ensenada], [del] Tajo Canyon, 25 – 27 - X- 1955, C. F. Harbison coll. / Ambrysus vanduzeei Usinger 1946 (Ira La Rivers) / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); [Mpio. Ensenada], 20 mi S of Santo Tomás, 03 - VIII- [19] 38 / Ross & Michelbacher colls. (4 ♂, 3 ♀ CAS); [Mpio. Mexicali], Guadalupe Canyon ,, 18 - V- 1957, F. X. Williams coll. (1 ♂ CAS); same but / Cal. Acad. / Ambrysus (1 ♂ CAS); [Mpio. Mexicali], Guadalupe Canyon, Sierra Juárez, 06 - VIII- 1955 / R. Orr & C. Tosa colls. (1 ♂ CAS); same but 21 - VI- 1988, Bauman, Kirschner, Kondratieff, Wells & Whiting colls. (1 ♀ BYU); [Mpio. Mexicali], Guadalupe C [a] n [yon], S [ierr] a Juárez, / 01 - XI- 1967, J. A. Gruwell coll. / California State Univ., Long Beach 1996 donation to Calif. Acad. Sci. (1 ♀ CAS); same but N. 59 / E. L. Sleeper coll. (1 ♂, 2 ♀ CAS). Chihuahua: [Mpio. Ahumada], Ojo Carbonera Spring on SW side of Ejido Rancho Nuevo, 06 - VI- 1979, M. L. Smith & B. Chernoff colls. BC 79 - 23 / Ambrysus sp. (Hemiptera: Naucoridae) (2 ♀ UMMZ); [Mpio. Casas Grandes], Ojo Barileño [Vareleño] 8 mi W of Nuevo Casas Grandes, 02 - V- 1978, R. R. Miller et al. colls, M- 78 - 45, Ambrysus Stål Naucoridae det. E. Bright June 2003 (1 ♂, 1 ♀ UMMZ); [Mpio. Janos], Ojo Caliente NW of Yanos [Janos], 29 - V- 1978, Miller, Marsh & Smith, M 78 - 14 (7 ♂, 4 ♀ UMMZ); [Mpio. Temósachi], Río Yepachic [at Yepachic, 5700 ’], CL 2324, 22 - IV- 1988, J. T. & D. A. Polhemus colls. (1 ♂ USNM). Sinaloa: [Mpio. Choix], Río Chinipas (Río La Plata) 21 mi NE Aqua Calienta [Agua Caliente], 20 - II- 1957, Miller coll. (1 ♀ UMMZ); [Mpio. Choix], Choix, Río Choix, CL 1643, 24 - IV- 1981, J. T. & D. A. Polhemus colls. / C. J. Drake Accession (2 ♀ USNM); [Mpio. El Fuerte, El] Fuerte, I- 2001, B. Heaton coll. (1 ♂, 1 ♀ BYU). Sonora: Mpio. Álamos, Arroyo La Vinatería at Taymuco (El Vado), 27 ° 14 ’ 39.7 ’’ N, 108 ° 43 ’ 17.3 ’’ W, 537 m, L- 1683, 25 - XII- 2013, Reynoso-Velasco, D. coll. (1 ♂, 4 ♀); Mpio Álamos, Rancho Acosta, 11 - IX- 1979, aquatic light trap / D. W. Moss, C. Y. Kitayama & G. W. Ulrich colls. (3 ♂, 3 ♀ EMEC): Mpio. Álamos, Río Mayo at Nahuibampo, 27 ° 22 ’ 28.8 ’’ N, 108 ° 54 ’ 34.4 ’’ W, 158 m, L- 1685, 26 - XII- 2013, Reynoso-Velasco, D. coll. (6 ♂, 4 ♀ UMC); [Mpio. Álamos], Upper Río Mayo [NW of San Bernardo, above Presa Bicentenario Los Pilares], CL 1636, 19 - IV- 1981, J. T. & D. A. Polhemus colls. / C. J. Drake Accession (2 ♂, 3 ♀ USNM); same but / Ambrysus sonorensis 1981 Usinger J. T. Polhemus (1 ♂ USNM); [Mpio. Nacozari], Rancho de Los Baños, CL 108, 03 - VI- 1975, J. T. Polhemus coll. / taken at night / C. J. Drake Accession (1 ♀ USNM); [Mpio. Nacozari], Rancho de Los Baños, CL 2316, 18 - IV- 1988, J. T. & D. A. Polhemus colls. (15 ♂, 4 ♀ USNM); same but 30 mi NE of Nacozari (2 ♂, 3 ♀ USNM); [Mpio. Navojoa], 1 mi SW Navojoa, 27 - VI- 1962 / E. L. Sleeper cool. / California State Univ., Long Beach 1996 donation to Calif. Acad. Sci. (2 ♂, 4 ♀ CAS); [Mpio. Yécora], [Arroyo Milpillas at] Tepoca [on Hwy 16], [1800 ’], CL 2317, 20 - IV- 1988, J. T. & D. A. Polhemus colls. (1 ♂, 3 ♀ USNM); [Mpio. Yécora], [spring in] rock tank 3 mi W of Yecora, [5100 ’], 20 - IV- 1988, CL 2319, D. A. & J. T. Polhemus colls. (1 ♂, 2 ♀ USNM); [Mpio. Yécora], 1 mi E Maicoba, 26 - IV- 1982, D. A. & J. T. Polhemus colls. / C. J. Drake Accession (15 ♂, 12 ♀ USNM); same but / Ambrysus occidentalis La Rivers det. J. T. P. (1 ♂ USNM); [Mpio. Yécora], 1 mi W Yécora, 26 - IV- 1982 D. A. & J. T Polhemus / C. J. Drake Accession (5 ♂, 4 ♀ USNM); same but / Ambrysus occidentalis La Rivers det. J. T. Polhemus (1 ♀ USNM); [Mpio. Yécora], 11 mi E [of] Yécora, 26 - IV- 1982, D. A. & J. T Polhemus / C. J. Drake Accession (6 ♂, 5 ♀ USNM); [Mpio. Yécora], 19 mi NE Yécora, 26 - IV- 1982, D. A. & J. T Polhemus / C. J. Drake Accession (1 ♂, 1 ♀ USNM); [Mpio. Yécora], 12 mi E of Maicoba, [4800 ’], CL 2323, 22 - IV- 1988, J. T. & D. A. Polhemus colls. (6 ♂, 5 ♀ USNM); stream pools 20 SE Esqueda, 26 - VI- 1168 [1968], F. N. Young coll. (1 ♀ UMC). UNITED STATES: Arizona: [Cochise Co.], Benson, 25 - III- 1933, Bryant coll. / Ambrysus occidentalis ‘ 70 La Rivers det. J. T. Polhemus / C. J. Drake Accession (1 ♂ USNM); [Cochise Co.], Douglas, 30 - IV- 1935, W. W. Jones / Presented by W. E. Jones / Ambrysus signoreti Stål det. R. I. Sailer (1 ♀ EMEC); Cochise Co., [F. H.] Snow coll. / Van Duzee Collct’n Acc. 4943 / A. signoreti det. V. D., Carnegie Museum (1 ♀ CMNH); Cochise Co., San Bernardino Ranch, 3750 ft, VIII- [no year], F. H. Snow coll. (1 ♂ UMC); same but Ambrysus occidentalis Usinger (sic) det. Hungerford (1 ♀ UMC); Cochise Co., 02 - IX- 1991, Coll. Loc. 2543, J. T. Polhemus coll. / Bear Cr., 6.5 mi W Coronado N. M. / C. J. Drake Accession (3 ♂, 4 ♀ USNM); same but / Topotype Ambrysus occidentalis La Rivers det. J. T. Polhemus (1 ♂ USNM); [Gila Co.], E [ast] Verde Riv [er], 7 mi N Payson, 11 - IX- 1958, A. Menke coll. / C. J. Drake Accession (3 ♂ USNM); same but / Ambrysus occidentalis La Rivers det. Menke ‘ 62 (1 ♀ USNM); Gila Co., East Verde River 7 mi N Payson, 11 - IX- 1958, Menke & Stange colls. / C. J. Drake Accession (1 ♂, 2 ♀ USNM); same but / Ambrysus occidentalis La Rivers (1 ♀ USNM); [Gila Co.], Tonto Creek, 20 - IV- 1904, F. M. Chamberlain coll. (1 ♀ USNM); same but 5.4 mi SE of Jakes Corner off Hwy 188, 01 - IX- 1990, D. P. Herman coll. (2 ♀ UMC); same but 1 – 2 - IX- 1990, J. A. Back (1 ♂, 1 ♀ UMC); same but 20 - XI- 1990, aquatic vegetation / algae (1 ♂ UMC); Gila Co., 5 mi SE Jake’s Corner, 18 - IV- 1982, D. A. & J. T Polhemus colls. / C. J. Drake Accession (1 ♀ USNM); Maricopa Co., Fish Creek E of Tortilla Flat, [upstream from bridge] along Hwy Arz. 88, 03 - XII- 1980, J. T. Polhemus coll. / CL 1624 (2 ♂, 1 ♀ USNM); Maricopa Co., Hassayampa [River] 5 mi S of Wickenburg, 26 - XI- 1984, D. A. Polhemus coll. (1 ♀ USNM); Maricopa Co., Salt River, 33 ° 33 ’ 27 ’’ N, 111 ° 36 ’ 28 ’’ W, elev. 1350 ft, 09 - VIII- 2021, rocks & algae, R. W. Sites, L- 2097 (5 ♂, 10 ♀ UMC); [Maricopa Co., Seven Springs Recreational Area] N of Carefree, 18 - I- 1972, CL 542, J. T. Polhemus coll. / seven springs / C. J. Drake Accession (5 ♀ USNM); Maricopa Co., 10 - VII- 1985, Jaime García coll. (1 ♂ UMC); Mojave Co., Burro Creek at Hwy 93, 15 - IV- 1988, D. A. & J. T. Polhemus colls. (2 ♂, 4 ♀ USNM); Pima Co., Sabino C [a] n [yon], [Santa] Catalina Mts., 25 - IX- 1957 (1 ♂ USNM); same but 10 - II- 1957 / C. W. O’Brien coll. (1 ♂ USNM); Pima Co., Tanque Verde Cnyn nr. Tucson, 06 - XI- 1988, R. Rathman coll. (2 ♂ UMC); Santa Cruz Co., pond on Ruby Rd nr. c [a] mpgr [oun] d at Peña Blanca lake, 10 - IV- 2011, G. Challet coll. (1 ♂, 1 ♀ UMC); Yavapai Co., Santa Maria River, 15 - IV- 1988. D. A. & J. T. Polhemus colls. (9 ♂, 3 ♀ USNM); [Yavapai Co.], 5 mi NE of Castle Hot Springs, CL 312, 07 - X- 1964, J. T. Polhemus coll. / C. J. Drake Accession (3 ♂, 2 ♀ USNM); same but / Ambrysus occidentalis La Rivers det. J. T. Polhemus (1 ♂ USNM); [Yuma Co.], Yuma, 07 - IV- 1879, 150 ft. / Andreas Bolter Collection / INHS Insect Collection 461,358 (1 ♀ INHS); [no specific locality], Arizona, [F. H.] Snow coll. / 1348 / Carnegie Museum (1 ♀ CMNH). California: [Los Angeles Co.], Pasadena, / from Geo. Frank / H. G. Barber coll. 1950 / L. signoreti Mont. det. Montandon / C. J. Drake Accession (1 ♂ USNM); Los Angeles Co., Santa Ana Canyon / Green River, 17 - X- 1937, Grace O. Wiley coll. / J. C. Lutz Collection 1961 (1 ♂ UMC); [Orange Co.], Modjeska Reservoir / 12 - II- 30, Norland / Limnocoris portheo? La Rives 1979 det. J. T. Polhemus / C. J. Drake Accession (1 ♀ USNM); Orange Co., San Juan Canyon, 16 - VII- 1979, CL 15, C. N. McKinnon coll. / Ambrysus occicentalis LaR det. C. N. McKinnon ‘ 80 / C. J. Drake Accession (1 ♂ USNM); [Orange Co.], San Juan Capistrano, jct. San Juan Ck. & San Diego Hwy., 24 - XII- 1976, C. N. McKinnon coll. / Ambrysus occicentalis LaR det. C. N. McKinnon ‘ 77 / C. J. Drake Accession (1 ♂ USNM); Orange Co., San Juan Creek, Hwy 74, [near San Juan Capistrano], CL 1621, 09 - XII- 1979, J. T. Polhemus coll. (1 ♂, 1 ♀ UMC); same but / C. J. Drake Accession (7 ♂, 8 ♀ USNM); same but / Ambrysus occidentalis La Rivers det. J. T Polhemus (1 ♂ USNM); Riverside Co., Corona, 9 - 14 - 1958 / M. E. Irwin coll. / C. J. Drake Accession (1 ♂, 1 ♀ USNM); Riverside Co., Santa Rosa Mts., Magnesia Springs Can [yon], 11 - XII- 1980, 500 ’ – 1200 ’, D. Giuliani coll. (1 ♀ CSCA); San Bernardino Co., Afton Canyon, Mojave River, 01 - I- 1956, Menke & Stange colls. / C. J. Drake Accession (2 ♂, 1 ♀ USNM); same but / Ambrysus occidentalis La Riv. det. Menke (1 ♀ USNM); [San Bernardino Co.], Hot Springs, 09 - VIII- 1922 / Ambrysus signoretii (sic) Stål / L. Eyrand coll. (1 ♀ UMC); [San Bernardino Co.], Zzyzx Springs, 13 - IV- 1968, CL 422, J. T. Polhemus coll. / C. J. Drake Accession (3 ♀ USNM); same but / Ambrysus occidentalis La Riv. det. J. T. Polhemus (1 ♀ USNM); San Diego Co., San Mateo Creek at Interstate 5, 13 - VII- 1984 / J. P. Webb coll. (1 ♂, 1 ♀ UMC).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	description	(Figs. 23 – 25)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 20 degrees close to proximal third, angled again at approximately 70 degrees at distal third (Fig. 23 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral corners narrowly rounded, posteromesal corners broadly rounded, posterior margin almost straight (Fig. 23 D). Phallosoma elongate, linear, slender, broadly rounded dorsoapically; left endosomal sclerite broad, plate-like, with oblique row of small denticles; right endosomal sclerite small, lightly sclerotized, with few denticles (Fig. 23 E). Parameres symmetrical, as long as maximum width, mesal margin convex. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 23 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	diagnosis	Diagnosis. This species can be distinguished from others in this section by the asymmetrical SGP with a ventrally deflexed small lobe on the left margin. Additionally, the posterolateral corners are pointed and the central lobe is clearly concave medially, giving the appearance of two pointed lobes (Fig. 23 B). Also, males exhibit the phallosoma broadly rounded to truncate dorsoapically, left endosomal sclerite plate-like with a few small denticles, and right endosomal sclerite inconspicuous with few small denticles (Fig. 23 E). Furthermore, both sexes exhibit the posterolateral corners of abdominal segments III – V strongly produced, robust, and spinose (Figs 23 A). Comparative notes. Other species in this complex also exhibit spinose posterolateral corners of abdominal segments III – V, but only those of A. inflatus La Rivers (Section 2) are as robust and strongly extending posteriorly as the corners of A. quadracies.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	discussion	Discussion. This species measures 9.37 – 12.25 in length and 6.87 – 8.12 in width. At the time of the description, La Rivers (1976) considered the posterior margin of the SGP of this species to be similar to that of his A. rotundus La Rivers. The four-pointed posterior margin is similar in both species; nonetheless, the central lobe of A. quadracies is deeply concave medially, giving the appearance of two pointed lobes, and in A. rotundus (= A. signoreti) it is only shallowly concave, giving the appearance of two rounded lobes. Although not mentioned by La Rivers, the lateral lobe on the left margin of the SGP is similar in both species. Recent phylogenetic studies (Reynoso-Velasco & Sites 2021, Sites 2022) suggest that A. quadracies is sister to a clade including A. lunatus and A. signoreti + A. sitesi. In the original description, La Rivers stated that the female holotype and the allotype (ergo a male) were part of the collection at Instituto de Biología (CNIN), while an additional female paratype was to be deposited in the collection of the Biological Society of Nevada (currently in the CAS). The specimen in the CNIN labeled as the allotype is actually a female and the additional paratype in the CAS is a male. These two specimens were probably mislabeled by La Rivers.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	description	Variation. Some females exhibit the SGP with the margin of the lateral lobe unsclerotized, sinuous, and not deflexed ventrally. Also, the posterolateral corners can be right-angled.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	materials_examined	Type locality. Mexico: Veracruz: Mpio. Catemaco, Catemaco. Repository. Female holotype (Fig. 24) is housed at the CNIN. Published records: MEXICO: Chiapas, Oaxaca, Veracruz (La Rivers 1976; Reynoso-Velasco & Sites 2018 b, 2019 b; Reynoso-Velasco 2021 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	distribution	Distribution. This species is distributed in the southern Mexico lowlands (majority of records below 200 meters) of the states of Chiapas, Oaxaca, and Veracruz (Fig. 25). All records are within the southern section of the Veracruzan biogeographic province. In the state of Chiapas, numerous specimens of this species were collected alongside or in the vicinity of the border with Guatemala and in some cases from rivers that originate in that country. Thus, this species clearly also occurs in Guatemala. Three female specimens of A. quadracies in the CNIN (2) and IEXA (1) have labels indicating they were collected in Cuernavaca, Morelos (see Material examined), which is 300 km northwest of the closest records in northern Oaxaca (L- 1880, L- 1881) and separated from the others presented here by the eastern section of the Sierra Madre del Sur mountain range. Thus, we consider it is doubtful that this species occurs in the state of Morelos; probably, the three female specimens were mislabeled.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB28FFCEFF71FF49AA7E5061.taxon	materials_examined	Type material examined. HOLOTYPE ♀ (by original designation). MEXICO: Veracruz: [Mpio. Catemaco], Catemaco / 10 - VI- 1964, L. Vázquez / Ambrysus quadracies Holotype ♀. PARATYPES: same data as holotype but / Ambrysus quadracies Allotype ♂ [incorrectly labeled as a male] (1 ♀ CNIN); same locality data but / Ambrysus quadracies Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS). Additional material examined. MEXICO: Chiapas: Mpio. Frontera Comalapa, Río Grijalva at El Caracol, 8 km S of Frontera Comalapa, 15 ° 36 ’ 07.0 ’’ N, 92 ° 09 ’ 14.5 ’’ W, 677 m, 31 - Mar- 2015, L- 1897, Reynoso-Velasco, Sites, Shepard & Barr colls. (13 ♂, 15 ♀ IEXA); Mpio. Ixtacomitán, Ixtacomitán, Balneario Río Blanco, 17 º 25 ’ 21.8 ’’ N, 93 º 06 ’ 08.6 ’’ W, 106 m, 17 - May- 2012, L- 1338, Reynoso-Velasco coll. (1 ♂, 1 ♀ IEXA); [Mpio. Ixtacomitán], Ixtacomitán, Río Blanco, 10 - XII- 85, col. F. Arias, L. Cervantes y R. Barba / Colección del Instituto de Biología, UNAM, México, D. F. (2 ♂, 2 ♀ CNIN; 1 ♂, 2 ♀ IEXA); Mpio. Maravilla Tenejapa, Ixcán, Río Ixcán at Pte. Ixcán, 16 ° 04 ’ 33.6 ’’ N, 91 ° 04 ’ 12.8 ’’ W, 175 m, 30 - Mar- 2015, L- 1896, Reynoso-Velasco, Sites, Shepard & Barr colls. (12 ♂, 5 ♀ CNIN; 32 ♂, 18 ♀ IEXA); Mpio. Maravilla Tenejapa, 13 de Septiembre, Río Puerto Rico at Pte. Puerto Rico, 16 ° 04 ’ 47.9 ’’ N, 91 ° 01 ’ 17.4 ’’ W, 163 m, 30 - Mar- 2015, L- 1895, Reynoso-Velasco Sites, Shepard & Barr colls. (2 ♂, 2 ♀ IEXA); Mpio. Ocosingo, Ruta Montes Azules, 30 - IV- 86, F. Arias / Colección del Instituto de Biología, UNAM, México D. F. (1 ♂ CNIN; 1 ♂ IEXA); [Mpio. Ocozocoautla de Espinoza], Arroyo Corzo at km 154 carr. Tuxtla Gutiérrez-Coatzacoalcos, 17 ° 03.189 ’ N, 93 ° 34.03 ’ W, 234 m, 25 - MAR- 2012, J. A. Gómez & R. Novelo colls. (3 ♂, 1 ♀ IEXA); [Mpio. Palenque], Palenque, CL 610, 13 - XII- 73, J. T. Polhemus (1 ♀ USNM); Mpio. Pichucalco, El Azufre, Pte. Azufre I, 17 ° 33 ’ 25.9 ’’ N, 93 ° 00 ’ 28.0 ’’ W, 49 m, 26 - Mar- 2015, L- 1882, Reynoso-Velasco, Sites, Shepard & Barr colls. (2 ♂, 1 ♀ IEXA); Mpio. Pichucalco, Río Pichucalco at Pte. Rosita, 4 km S of Pichucalco (800 m S of Río de Janeiro), 17 ° 29 ’ 07.2 ’’ N, 93 ° 06 ’ 13.5 ’’ W, 44 m, 27 - Mar- 2015, L 1883, Reynoso-Velasco, Sites, Shepard & Barr colls. (6 ♂, 4 ♀ IEXA); Mpio. Solosuchiapa, Solosuchiapa, Río La Sierra, 17 º 25 ’ 40.5 ’’ N, 93 º 01 ’ 35.7 ’’ W, 122 m, 17 - May- 2012, L- 1339, Reynoso-Velasco coll. (2 ♂, 2 ♀ IEXA; 13 ♂, 18 ♀ UMC); Mpio. Palenque, Ángel Albino Corzo (1 a Sección), Balneario (Sin Nombre), Río Chocolja, 17 ° 17 ’ 32 ’’ N, 91 ° 37 ’ 49.5 ’’ W, 119 m, 29 - Mar- 2015, L- 1888, Reynoso-Velasco, Sites, Shepard & Barr colls. (5 ♂, 1 ♀ CNIN; 12 ♂, 4 ♀ IEXA); Solaya [Solayó] - Río Laja [Lajas], 13 - XII- 85, F. Arias, L. Cervantes, R. Barba / Colección del Instituto de Biología, UNAM, México, D. F. (2 ♂, 1 ♀ CNIN; 2 ♂, 1 ♀ IEXA). Morelos: Cuernavaca, 10 - V- 50 / Colección del Instituto de Biología, UNAM, México D. F. (2 ♀ CNIN; 1 ♀ IEXA) [in doubt]. Oaxaca: Mpio. Ayotzintepec, San José Mano Marqués, 17 º 47 ’ 26.2 ’’ N, 96 º 00 ’ 15.3 ’’ W, 66 m, 24 - May- 2012, L- 1371, Reynoso-Velasco coll. (3 ♂, 3 ♀ CNIN; 5 ♂, 10 ♀ IEXA; 21 ♂, 20 ♀ UMC); Mpio. Jalapa de Díaz, Arroyo Espuma, 3 km SW of San Felipe, 18 ° 03 ’ 44.2 ’’ N, 96 ° 32 ’ 49.2 ’’ W, 152 m, 25 - Mar- 2015, L- 1880, Reynoso-Velasco, Sites, Shepard & Barr colls. (4 ♂, 1 ♀ IEXA); Mpio. Jalapa de Díaz, Sto. Domingo, Río Sto. Domingo, 18 ° 02 ’ 15.9 ’’ N, 96 ° 32 ’ 57.2 ’’ W, 100 m, L- 1881, 25 - Mar- 2015, L- 1881, Reynoso-Velasco, Sites, Shepard & Barr colls. (22 ♂, 13 ♀ IEXA); [Mpio. San José Chiltepec], Río Valle Nal., Peña Rubia, Km 13.1 Rta 175, 100 m, 9 - VII- 1996, R. Barba & A. Rojas / Colección del Instituto de Biología, UNAM, México D. F. (1 ♂, 1 ♀ CNIN; 1 ♀ IEXA); Mpio. San Juan Cotzocón, Arroyo Carrizal at km 110 carr. Palomares-Tuxtepec, 17 º 26 ’ 55.6 ’’ N, 95 º 26 ’ 39.1 ’’ W, 94 m, 22 - May- 2012, L- 1365, Reynoso-Velasco coll. (2 ♂, 2 ♀ IEXA; 4 ♂, 2 ♀ UMC); Mpio. Santiago Jocotepec, carr. La Alicia-Reforma, ca. 8 km E of Ayotzintepec, 17 º 40 ’ 10.2 ’’ N, 96 º 04 ’ 21 ’’ W, 108 m, 23 - May- 2012, L- 1370, Reynoso-Velasco coll. (1 ♂ UMC); Mpio. Santiago Jocotepec, La Alicia, 17 º 38 ’ 57.9 ’’ N, 96 º 00 ’ 38.7 ’’ W, 103 m, 23 - May- 2012, L- 1369, Reynoso-Velasco coll. (3 ♀ UMC); Mpio. Santiago Jocotepec, Río Tesechoacán at Centro Ecoturístico Cerro Chango, 17 º 42 ’ 06.6 ’’ N, 95 º 54 ’ 01.6 ’’ W, 54 m, 23 - May- 2012, L- 1367, Reynoso-Velasco coll. (3 ♂, 3 ♀ IEXA; 2 ♂, 3 ♀ UMC); Mpio. Santiago Jocotepec, Río Tesechoacán 3.5 km S of San José Río Manso, 17 º 38 ’ 44.3 ’’ N, 95 º 52 ’ 02.1 ’’ W, 61 m, 23 - May- 2012, L- 1368, Reynoso-Velasco coll. (4 ♂, 2 ♀ UMC). Veracruz: [Mpio. Catemaco], Catemaco, 23 - II- 60 / Colección del Instituto de Biología, UNAM, México D. F (1 ♂ IEXA); same but 10 - VI- 64, L. Vázquez / Colección del Instituto de Biología, UNAM, México D. F. (1 ♀ IEXA); [Mpio. Catemaco], Catemaco, 10 - VI- 64 (3 ♀ CNIN; 2 ♀ USNM); same but / Topotype Comp. @ type J. T. Polhemus ‘ 85 / Ambrysus quadracies Ira La Rivers det. J. T. Polhemus (1 ♀ CNIN); [Mpio. Catemaco], Coyame, Lago Catemaco, 4 - V- 64, B. Ayala / Colección del Instituto de Biología, UNAM, México D. F. (1 ♀ CNIN); same but 7 - II- 1965 B. Ayala / Colección del Instituto de Biología, UNAM, México D. F. (3 ♂, 5 ♀ UMC); Mpio. Santiago Sochiapan, Río Lana at Pte. Río Lana, 17 º 32 ’ 49.8 ’’ N, 95 º 34 ’ 31.6 ’’ W, 53 m, 23 - May- 2012, L- 1366, Reynoso-Velasco coll. (2 ♂, 2 ♀ IEXA; 2 ♂ UMC).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	description	(Figs. 26 – 28)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 40 degrees close to proximal third, angled again at approximately 70 degrees at distal third (Fig. 26 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral and posteromesal corners broadly rounded, posterior margin distinctly concave (Fig. 26 D). Phallosoma elongate, linear, slender, tapering dorsoapically; endosoma apically sclerotized on left side, subtriangular, granulose (Fig. 26 E black arrow); left endosomal sclerite subtriangular, with denticles; right endosomal sclerite knob-like, with denticles (Fig. 26 E). Parameres symmetrical, almost as long as maximum width, mesal margin almost straight. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 26 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	diagnosis	Diagnosis. Ambrysus scalenus can be easily distinguished from other species in this section by the distinctly asymmetrical female SGP with a broad, plate-like, and apically truncate lobe on the left margin. Additionally, the posterolateral corners are asymmetrical and the central lobe is almost truncate (Fig. 26 B). Also, males exhibit the phallosoma with the endosoma apically sclerotized on the left side, right endosomal sclerite knob-like, and left endosomal sclerite subtriangular; both sclerites with conspicuous denticles (Fig. 26 E). Furthermore, specimens of A. scalenus present a characteristic pattern profusely marked with dark dots over reddish areas on the scutellum and reddish marks at the lateral margin and posterolateral angle of the corium (Fig. 26 A). Comparative notes. Within this section, females of A. sitesi also exhibit a broad lateral lobe at mid-length on the left margin of the SGP; however, this lobe is evenly rounded and less extended laterally. The condition of the male endosoma in A. scalenus is comparable to that present in A. altiplanus, A. inecol, and A. magniceps; however, this feature is subtriangular in A. scalenus, lobe-shaped in A. altiplanus, and digitate in the other two species. The dark-spotted pattern on the corium is to some extent similar to that exhibited by A. harmodius La Rivers (Section 2).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	discussion	Discussion. Ambrysus scalenus measures 10.08 – 12.00 in length and 6.72 – 7.68 in width. The distinct dark-spotted pattern on the corium confers a resemblance to the Costa Rican A. harmodius; nonetheless, differences in the shape of the female SGP and male pseudoparameres and AGP suggest these two species are not closely related. Based on the shape of the male pseudoparameres and overall appearance, this species could be closely related to A. hydor and A. occidentalis. The Bayesian inference approach in the phylogenetic study by Reynoso-Velasco & Sites (2021) recovered A. scalenus as sister to a clade with five species, including A. hydor and A. occidentalis.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	description	Variation. The lobe on the left margin of the female SGP can be rounded apically. Additionally, the right posterolateral corner can be blunt.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	materials_examined	Type locality. Mexico: Michoacán: Mpio. Uruapan, El Sabino. Repository. Male holotype (Fig. 27 A) is housed at the SEMC. Published records. MEXICO: Estado de México, Guerrero, Michoacán, Oaxaca, Puebla (La Rivers 1953 a; Reynoso-Velasco & Sites 2016 a, 2018 a, 2018 b, 2019 b; Reynoso-Velasco 2021 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	distribution	Distribution. This species is distributed exclusively in central Mexico, in Estado de México, Guerrero, Michoacán, Oaxaca, and Puebla (Fig. 28). Distribution records of Ambrysus scalenus, all below 2,000 meters, are exclusively within the Balsas Basin biogeographic province; thus, this species is considered to be endemic to this province. The species has not been reported from Morelos, but this state is within the upper section of the Balsas Basin; consequently, the species is expected to also be distributed in this state.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB27FFCAFF71F965AD105429.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation): MEXICO: Michoacán: Mpio. Uruapan, El Sabino, [prob. Río Cajones], 28 - VII- 1936, H. D. Thomas coll. / Ambrysus scalenus La Rivers HOLOTYPE. PARATYPES: same data as holotype but / Ambrysus scalenus La Rivers Paratype (3 ♂, 4 ♀ EMEC; 53 ♂, 67 ♀ SEMC); same but / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (6 ♂, 8 ♀ CAS). Additional material examined. MEXICO: Estado de México: Mpio. Amatepec, Las Adjuntas, Río San Felipe, 05 - Mayo- 2008, Novelo & Cuevas colls. (1 ♀ UMC); [Mpio. Tejupilco], Acamochitlan, El Zapote, [El Zapote de Acamuchitlán], 21 - XI- 1984, H. Brailovsky / Colección del Instituto de Biología, UNAM, México D. F. / C. J. Drake Accession (2 ♀ USNM); [Mpio. Tejupilco], Bejucos, Río Bejucos, 700 m, 22 - Abr- 2004, R. Novelo coll. / Ambrysus sp. R. Novelo det. 2004 (4 ♂, 1 ♀ UMC); [Mpio. Tejupilco], Bejucos, Río Bejucos, 1950 ’, 22 - IV- 2004 / William D. Shepard, leg. (1 ♀ EMEC); [Mpio. Tejupilco], Bejucos, Temascaltepec, 3 - VII- 1933 / H. E. Hinton & R. L. Usinger colls. / Ira La Rivers Collection Bequeathed to the California Academy of Sciences (1 ♂ CAS); Mpio. Tejupilco, Paso de Vigas, Arroyo Paso de Vigas, 18 º 53 ’ 32.6 ’’ N, 100 º 13 ’ 57.0 ’’ W, 1107 m, L- 1459, 19 - Dec- 2012, Reynoso-Velasco coll. (6 ♂, 1 ♀ UMC); same but 5 - Apr- 2015, L- 1909, Reynoso-Velasco, Sites, Shepard & Barr colls. (1 ♂, 1 ♀ CNIN; 1 ♂, 1 ♀ IEXA; 2 ♂, 2 ♀ UMC); [Mpio Tonatico], Tonatico, VII- 1961 / Colección del Instituto de Biología, UNAM, México D. F. (1 ♂ CNIN, 1 ♀ IEXA); Tejupilco, Mex., Temascaltepec, 24 - VI- 1933 / H. E. Hinton & R. L. Usinger colls. (1 ♂ CAS); same but 17 - VI- 1933 / Ira La Rivers Collection Bequeathed to the California Academy of Sciences (1 ♀ CAS). Guerrero: Km 154 carr. Iguala – C [iu] d [ad] Altamirano, 23 - XI- 1984, H. Brailovsky coll. / Colección del Instituto de Biología, UNAM, México D. F. (1 ♀ CNIN); same but / C. J. Drake Accession (1 ♀ USNM); same but E. Barrera coll. (1 ♂, 1 ♀ USNM); [Mpio. Eduardo Neri], 9 mi N of Zumpango, 8 - Jan- 1956, J. C. Shafftner / Prop. of J. C. Shafftner / C. J. Drake Accession (2 ♂ USNM); Mpio. Teloloapan, km 20 carr. Teloloapan-Apaxtla de Castrejón, nr. Tepozanalquillo, 18 º 14 ’ 26.8 ’’ N, 99 º 54 ’ 51 ’’ W, 1083 m, 29 - Dec- 2012, L- 1497, Reynoso-Velasco coll. (1 ♀ UMC); Ruta El Caracol, approx .. km 38 Teloloapan, 22 - X- 1988, J. Bueno coll. / Colección del Instituto de Biología, UNAM, México D. F. (1 ♀ IEXA). Michoacán: Mpio. Buenavista, Buenavista Tomatlán, 19 º 12 ’ 57.8 ’’ N, 102 º 34 ’ 30.2 ’’ W, 440 m, 24 - Dec- 2012, L- 1481, Reynoso-Velasco coll. (2 ♀ UMC); Mpio. Carácuaro, Río San Diego at Carácuaro, 19 º 01 ’ 04.8 ’’ N, 101 º 07 ’ 33.2 ’’ W, 519 m, 22 - Dec- 2012, L- 1473, Reynoso-Velasco coll. (1 ♂ UMC); Mpio. La Huacana, La Huacana, Colonia Lázaro Cárdenas, 18 º 57 ’ 19 ’’ N, 101 º 48 ’ 43.2 ’’ W, 458 m, L- 1478, 23 - Dec- 2012, Reynoso-Velasco coll. (1 ♂, 1 ♀ UMC); Mpio. Nocupétaro, San Antonio de la Huerta (Melchor Ocampo), 19 º 02 ’ 04.4 ’’ N, 101 º 15 ’ 07.9 ’’ W, 624 m, 22 - Dec- 2012, L- 1475, Reynoso-Velasco coll. (1 ♂ IEXA); Mpio. Tepalcatepec, Los Horcones, Pte. Pinolapa at km 31 carr. Tepalcatepec-Coalcomán, 19 º 00 ’ 31.3 ’’ N, 103 º 01 ’ 25.6 ’’ W, 554 m, 25 - Dec- 2012, L- 1484, Reynoso-Velasco coll. (3 ♂, 2 ♀ UMC); [Mpio. Tepalcatepec], Tepalcatepec, Río Pinolapa, 16 - May- 2002, R. Novelo coll. (1 ♀ UMC); Mpio. Tuzantla, Río Tuzantla at Tuzantla, 19 º 13 ’ 18.1 ’’ N, 100 º 34 ’ 05.5 ’’ W, 593 m, 21 - Dec- 2012, L- 1470, Reynoso-Velasco coll. (1 ♂ IEXA). Oaxaca: [Mpio. Santiago Cacaloxtepec], 12 mi SE of Huajuapan [de León], 4 - VII- 1953, 6000 ft / Univ. Kans. Mex. Expedition / Slesnick Field No. 33 / Ambrysus scalenus La Rivers (5 ♂, 3 ♀ SEMC); same but / Ira La Rivers Collection Bequeathed to the California Academy of Sciences (1 ♀ CAS). Puebla: [Mpio. Ahuehuetitla], 10 mi SE of Tehuitzingo, 3900 ft, 3 - VII- 1933 / Univ. Kans. Mex. Expedition / Slesnick Field No. 32 / Ambrysus scalenus La Rivers 1953 (Ira La Rivers) (1 indet. SEMC).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	description	(Figs. 29 – 34)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	description	Male. Accessory genitalic process of tergum VI (AGP) curved to right at approximately 30 degrees close to proximal third, angled again at approximately 70 degrees at distal third (Fig. 29 C). Medial lobes of tergum VIII (pseudoparameres) symmetrical, posterolateral corners narrowly rounded, posteromesal corners broadly rounded, posterior margin straight (Fig. 29 D). Phallosoma elongate, linear, slender, tapering dorsoapically; without endosomal sclerites (Fig. 29 E). Parameres symmetrical, almost as long as maximum width, mesal margin almost straight. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin (Fig. 29 F).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	diagnosis	Diagnosis. Ambrysus signoreti can be easily distinguished from other species in this section by the almost symmetrical SGP that exhibits the lateral lobes rounded and ventrally deflexed. The lobe on the right margin is smaller. Additionally, the posterolateral corners are subtriangular and pointed and the central lobe is concave medially, giving the appearance of two rounded lobes (Fig. 29 B). A unique feature in males of this species is the absence of endosomal sclerites (Fig. 29 E). Comparative notes. Only A. cayo and A. quadracies exhibit a similar female SGP with a ventrally deflexed lobe on the left margin; nonetheless, in A. cayo the posterolateral corners are dorsally reflexed and the central lobe has the appearance of two pointed lobes. Ambrysus quadracies also has a central lobe that appears as two pointed lobes, but its posterolateral corners are not reflexed. Although the posterolateral corners of the SGP in A. signoreti are also pointed, its central lobe has the appearance of two rounded lobes. Additionally, the absence of both endosomal sclerites in the male phallosoma of A. signoreti is a unique feature among members of the complex. Paradoxically, the lack of these sclerites also implies the absence of denticles on their surface, which is the most important unifying feature among species in the A. signoreti complex; nonetheless, molecular evidence strongly supports the inclusion of A. signoreti in this complex (Reynoso-Velasco & Sites 2021).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	discussion	Discussion. This species measures 11.00 – 15.00 in length and 7.30 – 10.00 in width. Ambrysus signoreti was the first species to be described in the genus (Stål 1862) and later designated as the type species by Kirkaldy (1906). Stål did not specify the number of specimens used in the species description, but relevant information from the brief and superficial original description is that: 1) the new species was 13 mm in length and 9 mm in width, 2) the specimen (s) was (were) from the Signoret Collection (no repository indicated), and 3) “ the specimen ” or at least some of “ the specimens ” had been incorrectly identified as belonging to Naucoris poeyi Guérin-Méneville (= Pelocoris poeyi). Two male specimens (Fig. 31) currently housed in Vienna (NHMW) have a label from the Signoret Collection and another label identifying them as “ poeyi Guer. ” Furthermore, in his Enumeratio Naucoridarum, Stål (1876) reported the specimen (s) of his A. signoreti to be in Stockholm (NHRS), where currently a single female specimen of the species is housed (Fig. 30). This female is 12.96 mm in length and 8.32 mm in width and agrees with Stål’s measurements for his species. Also, NHRS is the repository of numerous type specimens used by Stål in the four parts of his work Hemiptera Mexicana, some of which were originally cited as belonging to the Signoret Collection. The same specimens, from both collections, were reported by Montandon (1897) in the work in which he erected the subfamily Cryphocricinae. The two specimens of A. signoreti in the NHMW bear Montandon’s determination label (Fig. 31). The evidence suggests that at least the above-mentioned three specimens were most likely examined by Stål and used to describe his A. signoreti; consequently, they are considered syntypes. One of the males (Inv. No. 000 023 598) in the NHMW has a red type-label (Fig. 31 left) as does the female in the NHRS (Fig. 30). Many of Stål’s specimens of Rhyparochromidae (Heteroptera: Pentatomorpha) in the NHRS bear the red typus - label; nonetheless, Scudder (1977) stated that Stål did not place the labels on his specimens, as the typological concept had not been stablished at the time of the original descriptions. The labels were placed on the pins at a later time, presumably by a museum worker. Based on this, it can be assumed that the same happened with the type-labeled male specimen of A. signoreti in the NHMW. To create taxonomic stability on the name of this species and because the female subgenital plate is the most important feature for species identification in this genus, the female specimen in the NHRS (Fig. 30), considered by La Rivers (1957 b, 1958) as “ the type ” of the species, is herein designated as the lectotype of Ambrysus signoreti. Accordingly, the two male specimens in the NHMW (Fig. 31) are designated as paralectotypes. La Rivers was not able to examine the specimens of A. signoreti in the NHMW and NHRS for his revision of the genus in Mexico. His concept of the species was based on a [brief and superficial] description of the species by Montandon (1897) and camera lucida drawings of the “ male and female accessory genitalic structures ” made by Usinger from material in the NHMW (La Rivers 1953 a: 1322). For that reason, his knowledge on the species at that time was inadequate. In his revision of Mexican representatives of the genus, La Rivers (1953 a) described A. portheo based on a male holotype and several paratype specimens from the northern Mexican state of Coahuila. Contrary to his own findings on the significance of the female SGP as “ perhaps the most important single basis for the species concept in Ambrysus ” (La Rivers 1951: 279), the author used characteristics of the male AGP as the basis to describe his new species (also evidenced by the designation of a male holotype). Additionally, he stated (La Rivers 1953 a: 1323): “ In Mexico proper, from the sparse available evidence, A. signoreti seems to be closest to A. portheo, and future material may show the latter to be a variable unit of the A. signoreti population per se. The accessory genitalic structures of the two, however, denote two separable entities with present material. ” Furthermore, in his work entitled “ New records of Ambrysus from Mexico ”, La Rivers (1958) stated: “ it appears that my A. portheo is a variant of A. signoreti; connexival spination and female subgenital plate terminal outlines are somewhat exaggerated over the condition found in the Stockholm Stål type, but otherwise there seem to be no specific differences. ” The shape of the male AGP is instructive for species recognition (Reynoso-Velasco & Sites 2016 a, 2016 b, 2018 a, 2018 b), although this feature exhibits variation and sufficient similarity among species that reliance on it alone can lead to misidentification. The female SGP in the allotype of A. portheo (Fig. 32 B) exhibits the characteristic features present in the lectotype of A. signoreti: ventrally deflexed lateral lobes on both margins, subtriangular posterolateral corners, and central lobe concave medially, giving the appearance of two rounded lobes (compare SGP in Fig. 30 with Fig. 32 B). Additionally, after examination of approximately 800 male specimens from various collections, it can be asserted that the difference in shape of the male AGP exhibited by the male holotype and several paratypes of A. portheo falls within the range of variation observed in males of A. signoreti; consequently, A. portheo is herein designated as junior synonym of A. signoreti. In a similar way, La Rivers (1962) described the species A. rotundus based on four specimens from El Salto and Tamazunchale, in the Mexican state of San Luis Potosí. In the original description, the holotype was reported to be a male, but the specimen in the CAS labeled as holotype is a female (Fig. 33). Examination of the specimens in the type series (CAS), two males and two females, revealed they belong to A. signoreti. The females, including that labeled as the holotype, exhibit the characteristic SGP shape of A. signoreti. Similar to A. portheo, the shape of the male AGP in the two males of A. rotundus in the type series falls within the range of variation observed in males of A. signoreti; accordingly, A. rotundus is herein designated as junior synonym of A. signoreti. At the time of the description of A. rotundus, La Rivers was already able to examine the female specimen of A. signoreti in the NHRS (the specimen herein designated as lectotype), as he published a work with the re-description of this specimen (La Rivers 1957 b). Nonetheless, he apparently did not notice that females of his new species exhibited the same shape of the SGP as the lectotype of A. signoreti. Additionally, he also did not mention anything about his previously described A. portheo (La Rivers 1953 a), which according to the original description (La Rivers 1953 a: 1321) could be the same as the at-the-time poorly understood A. signoreti.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	description	Variation. In some cases, the lobes on both margins of the female SGP can be less developed and / or unnoticeably deflexed ventrally. The lobe on the left margin can be subtriangular. Also, the lobe on the right margin can be only slightly sclerotized along its margin. Only a few females present the central lobe clearly extending posteriorly further than the posterolateral corners. Some male specimens, including those in the type series of A. rotundus, exhibit an AGP that is slightly longer in its apical third.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	materials_examined	Type locality. Mexico. Repository. Female lectotype (Fig. 30) is housed at the NHRS. Published records: MEXICO: Coahuila, Hidalgo, Nuevo León, Puebla, Querétaro, San Luis Potosí, Tamaulipas, Veracruz (Reynoso-Velasco & Sites 2018 a, 2018 b; Reynoso-Velasco 2021 b).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	distribution	Distribution. Knowledge on the distribution of this species was limited since the time of its description (Stål 1862) in the second half of the 19 th century. Early authors (e. g., Uhler 1876, Champion 1901, Hungerford 1920) reported this species from southwestern United States (Arizona, California, Colorado, New México), but La Rivers (1951) clearly stated that those records were based on misidentified specimens belonging to at least four species: Ambrysus arizonus La Rivers, A. mormon Montandon (both in the A. guttatipennis Stål species complex), A. lunatus (Section 2), and particularly A. occidentalis. In his revision of the genus Ambrysus in the United States, La Rivers (1951) inaccurately stated that A. signoreti had been described from central Mexico. In fact, Stål (1862) did not provide a specific locality for the species in the original description. The provenance of the naucorid species described there has been inferred only from the title of the work, “ Hemiptera Mexicana. ” No further mention on the distribution of the species was made in the study on the Ambrysus in Mexico (La Rivers 1953 a). It was not until a century and a half after the original description was published that the first specific localities for A. signoreti from Mexico where presented. The species was first reported from Río Panhuatlán and Río Calabozo in the states of Puebla and Veracruz, respectively (Reynoso-Velasco & Sites 2018 a). Later, it was also reported from Río Santa María in Veracruz (Reynoso-Velasco & Sites 2018 b). Nonetheless, La Rivers (1958) reported A. signoreti from Ciudad Valles and Tampico, in the states of San Luis Potosí and Tamaulipas, respectively, and the author stated: “ the specimens representative of the following records come closest to my conception of Stål’s A. signoreti, although I am still not satisfied that they are that species. ” For that reason, Reynoso-Velasco (2021 b) did not report these as valid previously reported records. These specimens, now housed at the CAS, were examined for this study and positively identified as belonging to A. signoreti. In addition to the above-mentioned localities reported in the original descriptions, as A. portheo the species was reported from La Nogalera, in the state of Nuevo León (Sites & Nichols 1999) and as A. rotundus it was reported from near 1) Pedro Montoya and 2) Río Verde, in San Luis Potosí (Davis 1986). The specimens used by Davis (1986) to report the species from both sites, presumably in the collection at Texas A & M University, were not examined for this study; however, two specimens positively identified as belonging to A. signoreti and from the same series collected at “ two miles southeast of Pedro Montoya ” were available at the USNM (listed below in corresponding section). Based on the comprehensive study on the distribution of this species (Reynoso-Velasco 2021 b) and new records (mostly based on specimens of the synonymies herein proposed), we know that A. signoreti is distributed in the eastern part of Mexico (Fig. 34), in the Sierra Madre Oriental and parts of the Tamaulipas (southwestern section) and Veracruzan (upper section) biogeographic provinces (5 – 2000 meters), with the majority of localities below 1,000 meters. Most of the records are from localities in the Sierra Madre Oriental province, along the lowlands of its elongate valleys. The northern limit of the species distribution seems to be in Coahuila and Nuevo León, in the area where the northernmost border of the Sierra Madre Oriental and the southwestern limit of the Tamaulipas province come together. In the south, the limit seems to be the Coatzacoalcos River Basin, in the central section of the Veracruzan province. This is one of the few Mexican species of Ambrysus than can be commonly found in limestone streams.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB23FFD0FF71FD50ABE155F9.taxon	materials_examined	Type material examined. LECTOTYPE ♀ (by present designation). MEXICO: Mexico / signoreti Stål / 173, 53 / Typus / NHRS-JLKB 000023184 / Ambrysus signoreti Stål, 1862, LECTOTYPE ♀, des. Reynoso-Velasco 2022. PARALECTOTYPES (by present designation): Mexico, Coll. Signoret / poeyi Guer. det Signoret / signoreti Stål / Amb. signoreti Stål det. Montandon / Type / Ambrysus signoreti Stål det. A. L. Montandon [18] 96 / NHMWHemipt. - Inv. No. 000 023 598 / Ambrysus signoreti Stål, 1862, PARALECTOTYPE ♂, des. Reynoso-Velasco 2022 (NHMW); Mexico, Coll. Signoret / poeyi Guer. det Signoret / signoreti Stål / Amb. signoreti Stål det. Montandon / NHMW-Hemipt. - Inv. No. 000 023 599 / Ambrysus signoreti Stål, 1862, PARALECTOTYPE ♂, des. Reynoso-Velasco 2022 (NHMW). Type material examined of the synonymies. Ambrysus portheo. Nine specimens in the CAS (8) and USNM (1) were labeled by La Rivers as paratypes of this species, notwithstanding the specimens were not reported in the species description; thus, this material is cited in the Additional material examined section. The following list only includes the type specimens examined for this study that were reported in the original description. HOLOTYPE ♂: MEXICO: [Coahuila: Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers HOLOTYPE / Ambrysus portheo La Rivers determined by Ira La Rivers ‘ 50 (SEMC). PARATYPES: [Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers ALLOTYPE (1 ♀ SEMC); [Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers Paratype / SEMC 1125997 KUNHM-ENT (1 ♀ SEMC); same but SEMC 1125998 KUNHM-ENT (1 ♂ SEMC); [Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers Paratype (2 ♂, 3 ♀ SEMC); [Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers Paratype / Ambrysus portheo La Rivers determined by Ira La Rivers ‘ 50 / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); [Mpio. Saltillo], Saltillo, 1937, H. D. Thomas / Ambrysus portheo La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); [Mpio. Saltillo], Saltillo, H. D. Thomas / Ambrysus portheo La Rivers Paratype / This specimen has slightly larger connexival & slightly more exaggerated subgenital tip than F [emale] Stockholm signoreti type: otherwise same in size, proportions & color / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); [Mpio. Saltillo], Saltillo, Mex, H. D. Thomas / 176 / Ambrysus portheo La Rivers Paratype / Ambrysus portheo La Rivers determined by Ira La Rivers ‘ 50 (1 ♂ EMEC). Ambrysus rotundus. In the original description La Rivers (1962) stated that that a male and a female would be designated as holotype and allotype of the species, respectively. The specimen labeled as holotype in the CAS is a female. The four type specimens of this species were examined for this study. HOLOTYPE ♀: MEXICO: San Luis Potosí: [Mpio. El Naranjo], El Salto, 19 - VI- [19] 53 / Univ. Kans. Mex. Expedition / Ambrysus rotundus La Rivers HOLOTYPE / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / California Academy of Sciences Type No. 13404. PARATYPES: same data as holotype but / Paratype Ambrysus rotundus La Rivers Det. V. F. Lee 1978 (1 ♂ CAS); [Mpio. Tamazunchale], Tamazunchale, 21 - VI- 1953, 600 ft, Slesnick No. 11 / Univ. Kans. Mex. Expedition / Ambrysus rotundus La Rivers ALLOTYPE / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS); same but / Paratype Ambrysus rotundus La Rivers Det. V. F. Lee 1978 (1 ♂ CAS). Additional material examined. MEXICO: Coahuila: [Mpio. Saltillo], Augustura [prob. Ejido Angostura S of Saltillo, 25.336125, - 101.047581], 03 - III- 1936 (1 ♂ SEMC; 2 ♂, 1 ♀ USNM); same but Ambrysus guttatipennis Stål det. J. R. Davis [19] 94 (1 ♀ SEMC); [Mpio. Saltillo], Saltillo, 21 - XI- [19] 32, L. D. Tuthill coll. / Ambrysus portheo La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / an unpublished paratype Det. 1978 by Vincent F. Lee (2 ♂ CAS); [Mpio. Saltillo], 14 mi S of Saltillo, [approx. 25.328738, - 101.074975], 29 - VIII- 1969, J. Haddock & J. T Doyen leg., highly calcareous stream (17 ♂, 12 ♀ EMEC); same but / Ambrysus portheo La Rivers det. R. W. Sites 2011 (1 ♀ EMEC); [Mpio. Saltillo], 16 mi S of Saltillo [approx. 25.299119, - 101.087485], 08 - V- 1964, CL 1112, J. T Polhemus coll. (8 ♂, 4 ♀ USNM); same but / Ambrysus portheo Det. J. T. Polhemus (1 ♂, 1 ♀ EMEC; 1 ♂, 2 ♀ USNM); [Mpio. Saltillo], 20 mi S of Saltillo, [approx. 25.288080, - 101.091626], 07 - VIII- 1963, P. J. Spangler leg., (2 ♂, 1 ♀ USNM). Hidalgo: Mpio. Atlapexco, Atlaltipa Huitzotlaco, Río Venado at Pte. Atlaltipa, 21.03675, - 98.373528, 158 m, 27 - V- 2014, L- 1796, D. Reynoso coll. (11 ♂, 3 ♀ IEXA); Mpio. Calnali, Sierra Norte, 950 m, 19 - IV- 2001, R. Novelo coll. (1 ♂ IEXA); Mpio. Huejutla de Reyes, Río Caimantla at Huitzquilititla, 21.111083, - 98.456778, 203 m, 27 - V- 2014, L- 1795, D. Reynoso coll. (5 ♂, 5 ♀ IEXA); Mpio. Mezquititlán, Río Venados at Venados, 20.473028, - 98.68103, 1303 m, 05 - VI- 2013, L- 1515, Sites et al. colls., rocky slow stream w / heavy algae (12 ♂, 11 ♀ UMC); same but D. Reynoso et al. colls. (13 ♂, 19 ♀ UMC); Mpio. Metzquititlán, [Río Venados 2.5 km W of Venados], 20.473056, - 98.681111, 1303 m, 05 - VI- 2013, R. Novelo coll. (6 ♂, 16 ♀ IEXA); Mpio. San Felipe Orizatlán, Huextetitla, 21.162333, - 98.55739, 154 m, 07 - VI- 2013, L- 1525, Sites et al. colls., stream w / rocks and algae (10 ♂, 10 ♀ UMC); same but D. Reynoso et al. colls. (8 ♂ UMC); Mpio. San Felipe Orizatlán, Río San Pedro at San Felipe Orizatlán, 21.170444, - 98.59633, 173 m, 07 - VI- 2013, L- 1526, Sites et al. colls., bedrock with channels, sparse gravel strips, and algae (Elodea sp.) (1 ♂, 3 ♀ UMC); same but D. Reynoso et al. colls. (3 ♀ UMC); [Mpio. Tasquillo], Tasquillo, [approx. 20.560674, - 99.309548], 23 - VI- 1955, R. E. Beer et al. colls. (2 ♂ UMC); Mpio. Tlanchinol, 3.4 km W of Chalchocotipa on road to Santa Maria Catzotipan, 21.043444, - 98.60022, 528 m, 06 - VI- 2013, L- 1522, D. Reynoso et al. colls. (21 ♂, 18 ♀ UMC); Mpio. Xochiatipan, Nuevo Acatepec, Río El Encinal at Pte. Garcés Principal, 20.9399167, - 98.281917, 201 m, 27 - V- 2014, L- 1797, D. Reynoso coll. (4 ♂, 1 ♀ IEXA); Río Amasa [indeterminate river] 6 mi W of Huejutla on road to Tamazunchale [approx. 21.143973, - 98.504279], 19 - III- 1974, R. R. & F. H. Miller colls., M 74 - 50 (2 ♀ UMMZ); Río Venados, 08 - X- 1983 (3 ♂, 3 ♀ CNIN; 1 ♂ USNM); same but 06 - X- 1979, J. Padilla coll. (1 ♀ CNIN; 1 ♀ USNM); same but 11 - XI- 1983, Humberto coll. (3 ♂, 1 ♀ CNIN); same but 06 - X- 1983, M. Albores coll. (2 ♂, 1 ♀ CNIN); same but 08 - I- 1984 (2 ♂, 1 ♀ CNIN); same but 01 - IV- 1984 (1 ♀ CNIN); same but 05 - VIII- 1984 (1 ♂, 2 ♀ CNIN), same but 14 - X- 1984 (1 ♂, 2 ♀ CNIN). Nuevo León: Mpio. Allende, Allende, Río Ramos-Raíces, [approx. 25.259716, - 99.997641], 20 - VII- 1990, A. Contreras & A. Niño colls. (5 ♀ CNIN); [Mpio. Allende, Arroyo Lazarillos at] Las Cruces, [approx. 25.338244, - 100.069312], 29 - III- 1986, A. Contreras R. coll. (1 ♀ USNM); [Mpio. Apodaca], Apodaca, [approx. 25.784770, - 100.196326], 10 - X- 1974, J. A. Jiménez coll. (1 ♂ UMC); Mpio. Galeana, Ejido el Potosí, [approx. 24.844319, - 100.313103], 11 - XI- 1985, R. Barba coll. (1 ♂, 1 ♀ CNIN); same but S. Tufinio coll. (1 ♀ CNIN); Mpio. García, Río Pesquería, [approx. 25.803913, - 100.587028], 08 - XI- 1985, H. Rojas coll. (3 ♂, 4 ♀ CNIN); same but R. Barba coll. (2 ♂, 3 ♀ CNIN); same but S. Tufinio coll. (1 ♀ CNIN); Mpio. General Terán, Río El Pilón at La Unión, 25.3408889, - 99.582639, 243 m, 19 - V- 2014, L- 1775, D. Reynoso coll. (4 ♂, 1 ♀ IEXA); Mpio. [General] Zaragoza, El Salto, [approx. 23.971513, - 99.761075], 27 - IV- 1975, F. Holguín coll. (1 ♀ UMC); [Mpio. Guadalupe], Villa de Guadalupe, [approx. 25.668937, - 100.185200], 02 - VI- 1977, H. A. Barreras coll. (2 ♀ UMC); [Mpio. Iturbide], spring-fed stream 1 mi E of Iturbide, [approx. 24.725202, - 99.891828], 1400 m, 01 - V- 1988, CL 2344, D. A. & J. T. Polhemus colls. (3 ♂, 2 ♀ USNM); same but Ambrysus portheo La Rivers Det. J. T. Polhemus (6 ♂ USNM); [Mpio. Linares], Linares, 19, 22 - IV- 1930, Creaser-Gordon / Ambrysus portheo La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / an unpublished paratype Det. 1978 by Vincent F. Lee (1 ♂, 1 ♀ CAS); [Mpio. Linares], Río Cabezones 15.5 mi N of Linares on Rt 85, [approx. 24.990656, - 99.747215], 537 m, 26 - X- 1965, G. E. Ball & D. R. Whitehead colls. (1 ♂ USNM); [Mpio. Linares], Río Potosí [Río Cabezones, 15 mi S of Montemorelos, 1450 ’], 01 - V- [19] 88, CL 2345, J. T. & D. A. Polhemus colls. / Ambrysus portheo La Rivers Det. J. T. Polhemus (2 ♂, 2 ♀ USNM); [Mpio. Montemorelos], 17.5 mi W of Linares, [approx. 24.990664, - 99.747062], 25 - V- 1981, J. T. Doyen & J. K. Liebherr colls. (1 ♀ EMEC); Mpio. Santiago, [Arroyo La Chueca at] El Yerbaníz, [approx. 25.497809, - 100.180292], 18 - IV- 1986, A. Contreras R. coll. (1 ♂, 2 ♀ USNM); same but 27 - VI- 1987 (2 ♂, 2 ♀ USNM); [Mpio. Santiago], diverted stream at La Nogalera nr Cola de Caballo [waterfall, approx. 25.362416, - 100.162675], 855 m, 30 - IV- 1988, CL 2342, D. A. & J. T. Polhemus colls. (1 ♂, 2 ♀ USNM); same but / Ambrysus portheo La Rivers Det. J. T. Polhemus (1 ♂, 2 ♀ USNM); Mpio. Santiago, La Nogalera, ca. 5 mi. W of El Cercado, [approx. 25.368887, - 100.157903], 23 - VII- 1989, B. J. Nichols coll. (3 ♂, 1 ♀ UMC); Mpio. Santiago, Las Adjuntas, [approx. 25.300713, - 100.141405], 07 - XI- 1985, A. Contreras R. coll. (1 ♂, 2 ♀ USNM); same but R. Barba coll. (1 ♀ CNIN); same but R. Barba et al. colls. (22 ♂, 15 ♀ CNIN); same but 10 - XI- 1985 (6 ♂, 3 ♀ CNIN); Mpio. Santiago, near Las Adjuntas, 21 - VI- [19] 40, K. Knight coll., pool in river / Ambrysus portheo La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / an unpublished paratype Det. 1978 by Vincent F. Lee (1 ♂ CAS); [Mpio. Santiago], Potrero Redondo, CL 2341, 30 - IV- [19] 88, J. T. Polhemus & D. A. Polhemus colls. / Ambrysus portheo La Rivers Det. J. T. Polhemus (4 ♂, 4 ♀ USNM); [Mpio. Santiago], Presa La Boca, [approx. 25.418636, - 100.14309], 30 - IV- 1927, P. A. Hernández coll. (1 ♀ UMC; 1 ♀ USNM); San Pedro, 20 mi S of Monterrey, Nuevo León creek, 18 - XII- 1940, B. Schultz & W. McLane colls., swift creek with many rapids and pools (2 ♂, 2 ♀ UMMZ). Puebla: Mpio. Ahuacatlán, 7 km SW of Amixtlán on carr. Tepango-Amixtlán, 20.01075, - 97.826944, 1231 m, 04 - VI- 2012, L- 1414, D. Reynoso coll. (1 ♂ IEXA); Mpio. Cuetzalan del Progreso, Las Hamacas, 20.033222, - 97.44869, 819 m, 03 - VI- 2012, L- 1412, D. Reynoso coll. (1 ♂, 1 ♀ UMC); [Mpio. Jopala, Río Necaxa at] Patla, [approx. 20.246639, - 97.855005], 25 - III- 1977, H. Brailovsky coll. (1 ♀ CNIN); Mpio. San Felipe Tepatlán, Río Tecolutla 5 km N of San Felipe Teplatlán, 20.095944, - 97.80431, 364 m, 04 - VI- 2012, L- 1415, D. Reynoso coll. (11 ♂, 5 ♀ IEXA; 9 ♂, 15 ♀ UMC); Mpio. Tlacuilotepec, Río San Marcos at km 1 carr. 130 A. Camacho-Petlacotla, 20.408018, - 97.891545, 280 m, 24 - VII- 1987, R. Novelo coll. (3 ♂, 4 ♀ IEXA); Mpio. Tlacuilotepec, 2 km E of Papaloctipan, 20.422889, - 97.94394, 310 m, 05 - VI- 2012, L- 1417, D. Reynoso coll. (3 ♂, 3 ♀ UMC); Mpio. Tlaxco, Río Los Cajones ca. 2 km S of Acalman, 20.407444, - 98.06431, 785 m, 05 - VI- 2012, L- 1418, D. Reynoso coll. (3 ♂, 3 ♀ UMC); Mpio. Xicotepec, Villa Ávila Camacho (La Ceiba), Río San Marcos at Pte. San Marcos, 20.394444, - 97.87753, 239 m, 30 - IV- 1991, R. Novelo coll. (2 ♀ IEXA); same but 05 - VI- 2012, L- 1416, D. Reynoso coll. (15 ♂, 11 ♀ IEXA; 17 ♂, 23 ♀ UMC); Mpio. Zapotitlán de Méndez, Río Zempoala at Zapotitlán, 20.003778, - 97.72397, 671 m, 03 - VI- 2012, L- 1413, D. Reynoso coll. (8 ♂, 7 ♀ UMC). Querétaro: [Mpio. Arroyo Seco], Ayutla, Río Ayutla, [approx. 21.393834, - 99.582435], 14. VII. 2000, W. D. Shepard leg., WDS-A- 1331 (2 ♂, 2 ♀ UMC); [Mpio. Arroyo Seco], Río Ayutla at Ayutla, 21.3885, - 99.5865, 14 - VII- 2000, C. B. Barr / Ambrysus rotundus La Rivers det. R. W. Sites 2007 (4 ♂ 5 ♀ EMEC); Mpio. Arroyo Seco, Concá, Río Santa Maria nr. Cascada Concá, 21.4381667, - 99.639722, 556 m, 14 - V- 2014, L- 1759, D. Reynoso coll. (2 ♂, 1 ♀ IEXA); Mpio. Arroyo Seco, Las Adjuntas, Río Santa Maria at Pte. Ayutla, 21.3972778, - 99.581361, 511 m, 14 - V- 2014, L- 1758, D. Reynoso coll. (14 ♂, 15 ♀ IEXA), Mpio. Arroyo Seco, [Río Jalpan at] km 16 carr. Jalpan-Arroyo Seco, nr. El Trapiche, 21.332305, - 99.526889, 650 m, 14 - V- 2014, L- 1757, D. Reynoso coll. (21 ♂, 30 ♀ IEXA); Mpio. Arroyo Seco, Río Jalpan at El Trapiche, 21.5883, - 99.6997, 853 m, 15 - XI- 1997, G. Aguilar coll. (1 ♀ UAQE); Mpio. Jalpan [de Serra], Río Sta. María, 14 - X- 2000, Y. Rico & B. Domínguez colls. (1 ♀ UAQE); Mpio. Peñamiller, [Arroyo Higuerillas at] El Oasis, 21.00, - 99. [70], 1050 m, 20 - I- 1999, P. Alonso coll., Amb. Lótico (1 ♂ UAQE); same but 29 - V- 2009, E. Hurtado coll. (1 ♀ UAQE); [Mpio. Peñamiller], Peña Blanca, 06 - XI- 1997, G. Ortega & E. Barrera colls. (1 ♀ CNIN); same but Río Extóraz, 21.03130556, - 99.7405, 1256 m, 13 - V- 2014, L- 1752, D. Reynoso coll. (16 ♂, 6 ♀ IEXA); [Mpio. Peñamiller], Río Extóraz at Peñamiller, [approx. 21.047890, - 99.816149], 22 - III- 2012, Durán coll. (1 ♀ UAQE); Mpio. Peñamiller, Río Victoria 1 km S San Miguel Palmas, 21.086944, - 99.952778, 09 - VII- 2000, C. B. Barr coll. / Ambrysus rotundus La Rivers det. R. W. Sites 2007 (2 ♂ EMEC); same but [Río Victoria], R. Jones coll. (7 ♀ UAQE); Mpio. Pinal de Amoles, Cañón de la Angostura, Río Escanela, 21.1965556, - 99.605306, 1241 m, 13 - V- 2014, L- 1753, D. Reynoso coll. (1 ♀ IEXA); [Mpio. Pinal de Amoles], Río Extóraz at Bucareli, [approx. 21.034722, - 99.617500], 01 - VII- 2000, W. D. Shepard leg., WDS-A- 1325 (12 ♂, 12 ♀ UMC); same but 1300 m, 10 - VII- 2000, R. Jones coll. (2 ♂, 1 ♀ UAQE); [Mpio. Pinal de Amoles], Río Extóraz at Bucareli, Sierra Gorda Biosphere Reserve, 21.0350, - 99.6166, 11 - VII- 2000, C. B. Barr coll. / Ambrysus rotundus La Rivers det. R. W. Sites 2007 (9 ♂, 12 ♀ EMEC); Mpio. Pinal de Amoles, [Río Jalpan at] Escanelilla, 21.2018333, - 99.566972, 1152 m, 14 - V- 2014, L- 1756, D. Reynoso coll. (1 ♂ IEXA). San Luis Potosí: Mpio. Aquismón, Río Tampaón at Tanchachín, 21.8223611, - 99.148361, 309 m, 24 - V- 2014, L- 1794, D. Reynoso coll. (19 ♂, 12 ♀ IEXA); Mpio. Aquismón, Santa Anita, Arroyo El Nacimiento at Pte. El Nacimiento, 21.975611, - 99.19144, 177 m, 06 - VII- 2004, R. Novelo coll., pond (1 ♂ UMC); same but 24 - V- 2014, L- 1792, D. Reynoso coll. (3 ♂, 2 ♀ UMC); Mpio. Axtla de Terrazas, Cómoca, Río Tancuilín, 21.417472, - 98.895, 86 m, 08 - VI- 2013, L- 1532, D. Reynoso et al. colls. (3 ♀ UMC); Mpio. Cárdenas, Canoas, La Poza Azul, 21.951222, - 99.51067, 969 m, 09 - VI- 2013, L- 1536, Sites et al. colls., vegetated stream below dam (5 ♂, 3 ♀ UMC); [Mpio. Ciudad del Maíz, Arroyo Hondo at 14 mi E of] Ciudad del Maíz, CL 528, [22.4741, - 99.5078, 1100 m], 09 - I- 1971, M. & J. T Polhemus colls. / A. portheo La Rivers det. J. T. Polhemus / C. J. Drake Accession (1 ♂ USNM); [Mpio. Ciudad Valles], C [iudad] Valles, 08 - VIII- 1951, C. J. Drake coll. / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (3 ♂, 1 indt. CAS); Mpio. Huehuetlán, El Nacimiento de Huichihuayán, 21.459806, - 98.97744, 96 m, 08 - VI- 2013, L- 1533, Sites et al. colls., spring-fed cold stream with cobble (11 ♂, 18 ♀ UMC); same but D. Reynoso et al. colls. (2 ♀ UMC); [Mpio. El Naranjo], El Salto, 19 - VI- [19] 53 / Univ. Kans. Mex. Expedition (4 ♂, 1 ♀ SEMC); same but / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); same but / Ambrysus portheo La Rivers 1953 (Ira La Rivers) (1 ♂, 1 ♀ CAS; 2 ♂, 1 ♀ UMC; 1 ♂ USNM); [Mpio. El Naranjo], El Salto Falls, [approx. 22.586267, - 99.383520], 16 - VI- 1955, R. E. Beer et al. colls. (1 ♀ UMC); same but 17 - VI- 1956 (6 ♂, 5 ♀ SEMC); same but / Ambrysus guttatipennis Stål det. J. R. Davis [19] 94 (1 ♂, 1 ♀ SEMC); Mpio. El Naranjo, Río El Salto at El Meco, 22. 566167, - 99.35317, 326 m, 10 - VI- 2013, L- 1539, Sites et al. colls., vegetated margin of limestone stream (1 ♂ UMC); Mpio. Matlapa, Río Tancuilín at Tancuilín (Los Manantiales), 21.345833, - 98.86272, 113 m, 07 - VI- 2013, L- 1530, D. Reynoso et al. colls. (15 ♂, 14 ♀ UMC); Mpio. San Vicente Tancuayalab, Ejido El Álamo, Río Moctezuma, 21.719694, - 98.55464, 32 m, 10 - VI- 2013, L- 1540, Sites et al. colls., vegetated margins and cobble riffle (3 ♂, 1 ♀ UMC); same but D. Reynoso et al. colls. (2 ♂ UMC); Mpio. Tamazunchale, Río Moctezuma at Tamazunchale, 21.257667, - 98.80572, 128 m, 07 - VI- 2013, L- 1529, Sites et al. colls., side channel w / cascades, gravel, and vegetation (2 ♀ UMC); same but D. Reynoso et al. colls. (1 ♂ IEXA; 1 ♂, 1 ♀ UMC); [Mpio. Tamazunchale] Tamazunchale, 31 - II- [19] 51, H. D. Lattin / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂ CAS); same but / Ambrysus signoreti Stål 1862 (Ira La Rivers) (1 ♂, 2 ♀ CAS); [Mpio. Tamazunchale] Tamazunchale, 22 - VI- 1953, Slesnick coll. (1 ♀ USNM); same but 21 - VI- 1953, 600 ft., No. 11 / Univ. Kans. Mex. Expedition / Ambrysus hydor La Rivers (Ira La Rivers) / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♂, 1 ♀ CAS); Río Axtla, 20 - IV- [19] 32 / J. R. de la Torre Bueno Collection K. U. (1 ♀ SEMC); 2 mi SE of Pedro Montoya, 27 – 28 - VII- 1970, Murray, Phelps, Hart, & Schaffner colls. / A. rotundus La Rivers / J. T. Polhemus Collection (1 ♂, 1 ♀ USNM). Tamaulipas: [Mpio. Gómez Farias], Gómez Farias, [approx. 22.886104, - 99.012467], 05 - X- 1985, F. Arias coll. (2 ♂, 1 ♀ CNIN); same but M. García coll. (1 ♂ CNIN); same but L. Cervantes coll. (2 ♂, 1 ♀ CNIN; 1 ♂, 1 ♀ USNM); Mpio. Güemes, Río Corona ca. 6 km W of Estación Santa Engracia, 24.0087222, - 99.167806, 216 m, 21. V. 2014, L- 1782, D. Reynoso coll. (14 ♂, 12 ♀ IEXA); Mpio. Jaumave, Río Guayalejo [2.5 km SE of] San José de Salamanca, 23.454111, - 99.282417, 569 m, 22 - V- 2014, L- 1784, D. Reynoso coll. (3 ♂, 8 ♀ IEXA); Mpio. Jaumave, Río Guayalejo ca. 4 km S of Jaumave (toward Padrón y Juarez), 23.3725833, - 99.396528, 767 m, 22 - V- 2014, L- 1785, D. Reynoso coll. (4 ♀ IEXA); [Mpio. Llera], 1 - 2 mi west of Forlón, 08 - VIII- 1934, Smith & Dunkle colls. / Ambrysus portheo La Rivers Paratype / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / an unpublished paratype Det. 1978 by Vincent F. Lee (1 indt. CAS); same but / looks like lundbladi superficially but female plate is specifically distinct (1 ♀ CAS); [Mpio. Llera], 1 – 2 mi west of Forlón, 08 - VIII- 1934, Smith & Dunkle colls. / Ambrysus portheo La Rivers Paratype / Ambrysus lundbladi Usinger determined by Ira La Rivers ‘ 50 / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 / an unpublished paratype Det. 1978 by Vincent F. Lee (1 ♀ CAS); [Mpio. Llera], 1 - 2 mi west of Forlón, 08 - VIII- 1934, Smith & Dunkle colls. / Ambrysus portheo La Rivers Paratype / Ambrysus portheo La Rivers det. J. T. Polhemus / donated to AMNH by J. T. Polhemus / C. J. Drake Accession (1 ♀ USNM); Mpio. Padilla, Río Purificación at El Barretal, 24.077916, - 99.142028, 205 m, 21 - V- 2014, L- 1780, D. Reynoso coll. (23 ♂, 18 ♀ IEXA); [Mpio. Tampico], Tampico, 16 - VII- 1950, Drake & Hottes colls. / Ira La Rivers Collection bequeathed to the California Academy of Sciences - 1978 (1 ♀ CAS). Veracruz: [Mpio. Álamo Temapache, Arroyo Buena Vista] at bridge on Hwy 127, 1.3 mi W of jct with Hwy 180 to Tampico, and ca. 2 mi NW of Potrero del Llano, 21.099623, - 97.747728, 16 - XII- 1972, R. R. Miller et al. colls. (1 ♂, 2 ♀ UMMZ); [Mpio. Atzalán], El Filo, Río Filobobos, [approx. 19.927778, - 97.163611], 08. XI. 2009, R. Novelo coll. (29 ♂, 16 ♀ IEXA); same but 263 m, L. Cervantes et al. colls. (1 ♀ CNIN); [Mpio. Atzalán, Río Alseseca at], Pte. Tomata, [19.922250, - 97.223083], 12 - VII- 2002, R. Novelo coll. (1 ♀ IEXA); same but 500 m, 06 - IV- 2011, L- 1296, Sites et al. colls., rootmats and gravel riffles (1 ♀ UMC); same but 19.921028, - 97.2245, 514 m, 13 - VI- 2013, L- 1549, Sites et al. colls., rock and gravel riffles and marginal vegetation (17 ♂, 15 ♀ UMC); same but D. Reynoso et al. colls. (4 ♀ UMC); Mpio. Atzalán, Río Alseseca at Parque Ecoturístico El Pezma, 19.91225, - 97.2245, 541 m, 13 - VI- 2013, L- 1550, Sites et al. colls., high velocity river w / cascades (1 ♀ UMC); [Mpio. Catemaco] Río Cuetzalapan 2 mi E Lago Catemaco, [approx. 18.365334, - 94.994998], 12 - VII – 08 - VIII- 1964, J. R. Meyer coll. (1 ♀ USNM); Mpio. Citlaltepec, Citlaltepec, 21.329917, - 97.88336, 194 m, 11 - VI- 2013, L- 1544, D. Reynoso et al. colls. (2 ♂, 1 ♀ IEXA; 3 ♂, 2 ♀ UMC); [Mpio. Cotaxtla], Río Blanco [at Puente Río Blanco, 2 km S of La Tinaja, 18.741804, - 96.456120, 04 - I- 1971], CL 504, M. S. & J. T. Polhemus colls. (2 ♂, 2 ♀ USNM); Mpio. Ixhuatlán de Madero, Río Vinazco at Naranjo Dulce, 20.823583, - 97.922, 86 m, 27 - V- 2014, L- 1798, D. Reynoso coll. (20 ♂, 38 ♀ IEXA; 3 ♂ UMC); Mpio. Misantla, Río Chapachapa at Pte. Chapachapa, 19.970139, - 96.88544, 121 m, 14 - VI- 2013, L- 1554, D. Reynoso et al. colls. (7 ♂, 1 ♀ UMC); Mpio. Misantla, Río Kilate at Libertad, 20.051722, - 96.97761, 61 m, 14 - VI- 2013, L- 1552, Sites et al. colls., rocky stream w / algae (6 ♂, 6 ♀ UMC); same but D. Reynoso et al. colls. (8 ♂, 2 ♀ IEXA; 32 ♂, 30 ♀ UMC); Mpio. Misantla, ca. 2 km E of Libertad, 20.066528, - 96.95625, 56 m, 14 - VI- 2013, L- 1553, D. Reynoso et al. colls. (1 ♂, 1 ♀ UMC); [Mpio. Orizaba], Orizaba, 10 - XII- 1973, CL 603, J. T. Polhemus coll. (1 ♂ USNM); Mpio. Puente Nacional, Puente Nacional, Río La Antigua at Pte. Puente Nacional I, 19.3245833, - 96.48175, 67 m, 29 - V- 2014, L- 1801, D. Reynoso coll. (10 ♂, 8 ♀ IEXA); [Mpio. Puente Nacional, Río La Antigua at bridge N of] Conejos, [approx. 19.324153, - 96.482412], 06 - I- 1971, CL 515, M. S. & J. T. Polhemus colls. (1 ♀ USNM); Mpio. Santa Maria, 1 km W of Ixcatepec on road to Naranjos, Pte. Pepeyuca, 21.225111, - 97.99133, 166 m, 11 - VI- 2013, L- 1542, Site et al. colls., rock trickles btw pools w / vegetation and heavy algae (1 ♀ UMC); same but D. Reynoso et al. colls. (5 ♂, 3 ♀ IEXA); Mpio. Santa. Maria, 4 km W of Citlaltepec, 21.2905, - 97.91578, 223 m, 11 - VI- 2013, L- 1543, Sites et al. colls. (33 ♂, 30 ♀ UMC); same but D. Reynoso et al. colls. (23 ♂, 17 ♀ UMC); [Mpio. Soteapan], Ocotal Chico, [approx. 18.256519, - 94.856528], 04 - V- 85, H. Velasco coll. (3 ♂, 3 ♀ CNIN); same but M. Vértiz coll. (2 ♂, 1 ♀ CNIN); same but F. Arias coll. (2 ♀ CNIN); Mpio. Tantoyuca, Platon Sánchez, Río Calabozo, 21.285611, - 98.37739, 41 m, 06 - VI- 2013, L- 1524, D. Reynoso et al. colls. (1 ♂, 4 ♀ UMC); [Mpio. Tantoyuca, Río Calabozo], 15 mi S of Tempoal, [21.291777, - 98.356529], 08 - I- 1971, CL 524, J. T. & M. S. Polhemus colls. (1 ♂, 3 ♀ USNM); Mpio. Tlapacoyan, El Encanto, Río Filobobos, 08 - XI- 2009, R. Novelo coll. (1 ♂, 6 ♀ IEXA); same but 19.983639, - 97.169150, 178 m, L- 1123, Sites et al. colls. (4 ♂, 7 ♀ UMC); Mpio. Tlapacoyan, Río Filobobos, 19.927639, - 97.162717, 267 m, 08 - XI- 2009, L- 1124, Sites et al. colls. (131 ♂, 72 ♀ UMC); same but, 19.927722, - 97.16264, 281 m, 14 - VI- 2013, L- 1551, Sites et al. colls., gravel and rocky stream w / algae and marg. veg. (5 ♂, 8 ♀ UMC); same but D. Reynoso et al. colls. (83 ♂, 86 ♀ UMC; 8 ♂, 10 ♀ IEXA); same but R. Novelo coll. (2 ♂, 5 ♀ IEXA); Mpio. Tlapacoyan, Rojo Gómez, Río Filobobos, 20.044917, - 97.09403, 89 m, 12 - VI- 2013, L- 1548, D. Reynoso et al. colls. (2 ♀ UMC); [Mpio. Tlapacoyan], Tlapacoyan, 13 - IX- 1986, E. Barrera coll. (4 ♀ CNIN); same but E. Barrera & H. Brailovsky colls. (1 ♂, 1 ♀ CNIN); [Mpio. Tlapacoyan], Tlapacoyan, Río Tomata [Río Alseseca, approx. 19.921916, - 97.223626], 02 - VII- 1985, M. Espinosa coll. (2 ♂ CNIN); same but 03 - VII- 1985 (1 ♀ CNIN).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	description	(Figs. 35 – 36) Ambrysus sitesi Reynoso in Reynoso-Velasco & Sites 2019 a: Zootaxa 4615: 298 – 302 (original description).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	diagnosis	Diagnosis. This species can be easily distinguished from other species in this section by the asymmetrical female SGP with a broad and evenly rounded lateral lobe at mid-length on the left margin. Additionally, the posterolateral corners are short and digitate and the central lobe appears truncate (Fig. 35 B). Also, a distinctive feature of the males is the absence of the right endosomal sclerite of the phallosoma; only the left sclerite is present, which is convex and exhibits small rounded denticles along its margin (Fig. 35 E). Comparative notes. Only A. scalenus exhibits a similar left-lobed margin of the female SGP; however, the lobe extends further laterally and is truncate. The absence of the right endosomal sclerite in the male phallosoma is also a characteristic of A. lundbladi (Section 2); nevertheless, the existing left sclerite is smaller and inconspicuous in the latter species.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	discussion	Discussion. This recently described species measures 9.80 – 11.60 in length and 6.20 – 7.50 in width. In the original description, Reynoso-Velasco & Sites (2019 a) suggested a possible close relationship of A. sitesi and A. lundbladi based on the similar morphology of the endosomal sclerites exhibited by males of both species. This relationship was not supported in the molecular study by Sites (2022); instead, A. sitesi was sister to A. signoreti, while A. lundbladi was sister to A. inflatus in a different clade. Although a previous work (Reynoso-Velasco & Sites 2021) also found the sister relationship of A. sitesi and A. signoreti, the study did not include A. lundbladi. In his work on the Ambrysus of Mexico, La Rivers (1953 a) described the subspecies A. lunatus menoides (currently a synonym of A. lundbladi Usinger) from the states of Puebla and Chiapas. The type specimens of A. lunatus menoides from Chiapas were reported to be deposited only in the UMMZ. This collection has two males in total, which were examined and positively identified as belonging to A. sitesi. Additionally, the same case applies to a paratype-labeled female we found in the CAS. Since this collection was not reported as an original repository, we suspect this female specimen was donated to the CAS after the subspecies original description.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	description	Variation. No variation was detected on the diagnostic features.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	materials_examined	Type locality. Mexico: Oaxaca, Mpio. San Gabriel Mixtepec, Río Rana at San Gabriel Mixtepec, 16 º 06 ’ 06.3 ’’ N, 97 º 03 ’ 52.9 ’’ W, 712 m. Repository. Female holotype (Fig. 35 A) is housed at the IEXA. Published records: GUATEMALA: Huehuetenango; MEXICO: Chiapas, Oaxaca (Reynoso-Velasco & Sites 2019 a).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	distribution	Distribution. This species is distributed at elevations of 60 – 1200 meters in the southern Mexican states of Chiapas and Oaxaca and the western Guatemalan department of Huehuetenango (Fig. 36). Most records from Oaxaca are in the Sierra Madre del Sur biogeographic province, while those from Chiapas and Huehuetenango are in the Chiapas Highlands province. A few records from the northern part of both states in Mexico are on the border with the Veracruzan province. Additionally, at least one record from the southern part of Chiapas is in the Pacific Lowlands province.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB39FFDDFF71FBE0AA825233.taxon	materials_examined	Type material examined. HOLOTYPE ♀. MEXICO: Oaxaca: Mpio. San Gabriel Mixtepec, km 194 carr. Puerto Escondido-Oaxaca, San Gabriel Mixtepec, Río Rana, 16 º 06 ’ 06.3 ’’ N, 97 º 03 ’ 52.9 ’’ W, 712 m, 03 - Apr- 2015, L- 1906, Reynoso, Sites, Shepard & Barr colls. PARATYPES: same data as holotype (2 ♂, 2 ♀ CNIN; 10 ♂, 7 ♀ IEXA; 5 ♂, 4 ♀ UMC); Mpio. Jalapa de Díaz, Sto. Domingo, Río Sto. Domingo, 18 ° 02 ’ 15.9 ’’ N, 96 ° 32 ’ 57.2 ’’ W, 100 m, L- 1881, 25 - Mar- 2015, Reynoso, Sites, Shepard & Barr colls. (2 ♂, 6 ♀ IEXA; 1 ♂, 1 ♀ UMC); Mpio. Putla Villa de Guerrero, Pluta de Guerrero, 17 º 02 ’ 21.5 ’’ N, 97 º 54 ’ 42.9 ’’ W, 767 m, 30 - May- 2012, L- 1397, Reynoso-Velasco, D. coll. (1 ♂ UMC); Mpio. Sta. Maria Tecomavaca, carr. Tehuacán-San Francisco Telixtlahuaca, 16 km S of San Juan de los Cués, Río Salado, 17 º 55 ’ 50.5 ’’ N, 97 º 00 ’ 04.2 ’’ W, 544 m, 01 - Jun- 2012, L- 1407, Reynoso-Velasco, D. coll. (1 ♂ UMC). Chiapas: Mpio. Altamirano, Cuauhtemoc, Balneario Tzaconejá, Río Tzaconejá, 16 ° 41 ’ 17.5 ’’ N, 92 ° 01 ’ 03.0 ’’ W, 1172 m, 28 - Mar- 2015, L- 1886, Reynoso, Sites, Shepard & Barr colls. (6 ♂, 3 ♀ IEXA; 4 ♂ UMC); Mpio. Amatengo de la Frontera, Barrio Sabinalito, Río Agua Caliente, 15 ° 25 ’ 0.1 ’’ N, 92 ° 08 ’ 33.7 ’’ W, 942 m, L- 1898, 31 - Mar- 2015, Reynoso, Sites, Shepard & Barr colls. (4 ♂ IEXA); [Mpio. Ángel Albino Corzo], Finca Prusia, 10 - V- 85, M. Vértiz / Colección del Instituto de Biología, UNAM. México, D. F (1 ♂ CNIN); [Mpio. Ángel Albino Corzo], Finca Prusia, 12 - V- 85, F Arias / Colección del Instituto de Biología, UNAM. México, D. F (1 ♂, 2 ♀ CNIN); [Mpio. Ángel Albino Corzo], Finca Prusia, 12 - V- 85, H Velasco / Colección del Instituto de Biología, UNAM. México, D. F (3 ♂ CNIN); [Mpio. Ángel Albino Corzo], Finca Prusia, 12 - V- 85, M Vértiz / Colección del Instituto de Biología, UNAM. México, D. F (1 ♀ CNIN); Mpio. Ángel Albino Corzo, Río Prusia, 15 º 43 ’ 23.3 ’’ N, 92 º 47 ’ 46.5 ’’ W, 1010 m, 18 - May- 2012, L- 1345, Reynoso-Velasco, D. coll. (1 ♂, 4 ♀ UMC); Mpio. Frontera Comalapa, El Caracol, 8 km S of Frontera Comalapa, Río Grijalva, 15 ° 36 ’ 07.0 ’’ N, 92 ° 09 ’ 14.5 ’’ W, 677 m, 31 - Mar- 2015, L- 1897, Reynoso, Sites, Shepard & Barr colls. (1 ♂ IEXA); Mpio. Huixtla, Huixtla, Río Huixtla, 15 ° 08 ’ 59.9 ’’ N, 92 ° 27 ’ 04.6 ’’ W, 67 m, 31 - Mar- 2015, L- 1899, Reynoso, Sites, Shepard & Barr colls. (1 ♂ IEXA); Mpio. Ixtapa, Ixtapa, 16 º 48 ’ 43.7 ’’ N, 92 º 54 ’ 30 ’’ W, 1030 m, 17 - May- 2012, L- 1341, Reynoso-Velasco, D. coll. (6 ♂, 3 ♀ IEXA); [Mpio. Ixtapa], Ixtapa, # 132, 27 - IV- 1941, I. J. Cantrall / Ambrysus lunatus menoides La Rivers PARATYPE / Ira La Rivers Collection Bequeathed to the California Academy of Sciences- 1978 (1 ♀ CAS); Mpio. Ixtapa, Río Lajas at Pte. Río Lajas, 16 º 50 ’ 42.6 ’’ N, 92 º 54 ’ 01.7 ’’ W, 1020 m, 17 - May- 2012, L- 1340, Reynoso-Velasco, D. coll. (2 ♂, 1 ♀ UMC); same but 28 - Mar- 2015, L- 1885, Reynoso, Sites, Shepard & Barr colls. (10 ♂, 10 ♀ CNIN; 20 ♂, 21 ♀ IEXA; 6 ♂, 15 ♀ UMC); [Mpio. Ixhuatán], 4 mi N of Tapiula [Tapilula], CL 1097, 5 May 1964, JT & MS Polhemus (1 ♂, 1 ♀ USNM); [Mpio. Ocosingo], Ocosingo, June 25 1950, C. & M. Goodnight & L. Stannard, mountain stream / Chiapas, 25 - VI- 57, Mex. Stannard (1 ♂ SEMC); Mpio. Siltepec, km 72 carr. Jaltenango-Siltepec, nr. Nuevo Galeana, 15 º 35 ’ 54.9 ’’ N, 92 º 32 ’ 28.9 ’’ W, 933 m, L- 1349, 19 - May- 2012, Reynoso-Velasco, D. coll. (2 ♂, 1 ♀ UMC); Mpio. Siltepec, km 92 carr. Jaltenango-Siltepec, Campo Aéreo, Río Bravo, 15 º 35 ’ 17.9 ’’ N, 92 º 28 ’ 02.3 ’’ W, 1068 m, 19 - May- 2012, L- 1350, Reynoso-Velasco, D. coll. (1 ♂, 1 ♀ UMC); Mpio. Siltepec, Matasano, Río Matasano, 15 º 36 ’ 13.7 ’’ N, 92 º 33 ’ 37.1 ’’ W, 950 m, 19 - May- 2012, L- 1348, Reynoso-Velasco, D. coll. (6 ♂, 6 ♀ IEXA; 16 ♂, 19 ♀ UMC); Mpio. Solosuchiapa, El Beneficio, Río La Sierra, 17 ° 21 ’ 01.1 ’’ N, 93 ° 00 ’ 21.1 ’’ W, 303 m, 27 - Mar- 2015, L- 1884, Reynoso, Sites, Shepard & Barr colls. (1 ♂ UMC); Mpio. Solosuchiapa, Solosuchiapa, Río La Sierra, 17 º 25 ’ 40.5 ’’ N, 93 º 01 ’ 35.7 ’’ W, 122 m, 17 - May- 2012, L- 1339, Reynoso-Velasco, D. coll. (1 ♂ UMC); [Mpio. Soyaló], Soyalo, Rio Blanco, CL 1086, 4 May 1964, J. T. & M. S. Polhemus / C. J. Drake Accession (16 ♂, 10 ♀ USNM); Mpio. Tenejapa, ponds in stream above Habenal / 14. VII. 1964, coll. D. Breedlove / C. J. Drake Accession / CAS (2 ♂ USNM); Rio Laja [s] nr Bochil, CL 668, 6 - I- 74, J. T. Polhemus (9 ♂, 5 ♀ USNM); Soyalo, Rio Lajas, CL 1087, 4 - May- 1964, J. T. & M. S. Polhemus / A. guttatipennis close, No! / C. J. Drake Accession (1 ♀ USNM). GUATEMALA: Huehuetenango: Rio Nentón, ca. 8 km NE of La Laguna, 10 - May- 2013, 15.79915 º N, 91.88951 ºW, 613 m, R. S. Zack coll. (1 ♀ WSUC). Additional material examined. MEXICO: Chiapas: [Mpio. Ixtapa], Ixtapa, # 132, 27 - IV- 1941, I. J. Cantrall / Ambrysus lunatus menoides La Rivers PARATYPE (1 ♂ UMMZ); same but / Ambrysus lunatus menoides La Rivers determined by Ira La Rivers ‘ 50 (1 ♂ UMMZ).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	description	(Figs. 37 – 39)	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	diagnosis	Diagnosis. Ambrysus sonorensis can be distinguished from others in this section by the symmetrical female SGP with small and narrowly rounded lateral lobes and inconspicuous apical lobes at the base of the middle and apical thirds, respectively. Additionally, the posterolateral corners are short and rounded and the central lobe is poorly developed and shallowly concave medially, giving the appearance of two low and rounded lobes (Fig. 37 B). Also, the male phallosoma presents both endosomal sclerites knob-like with conspicuous denticles (Fig. 37 E). Comparative notes. Ambrysus sonorensis and A. altiplanus present the female SGP with low apical lobes, but these lobes are more distinct in A. altiplanus. Also, the SGP rounded posterolateral corners and broad central lobe of A. sonorensis are respectively pointed and narrow in A. altiplanus, and males of A. sonorensis do not have the diagnostic lobe-shaped and granulose sclerotized area of the endosoma present in the phallosoma of A. altiplanus.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	discussion	Discussion. This species measures 13.43 – 15.48 in length and 8.50 – 10.50 in width. Usinger (1946) described this species based on a single male specimen (Fig. 38) from the northern Mexican state of Sonora, hence the etymology of the specific epithet in the species name. In the original description, Usinger assigned this species to the A. signoreti complex, but did not give the features to establish such inclusion. Apparently, this is the first time the A. signoreti complex was mentioned in the literature. La Rivers (1953 a) considered it impractical to include this species in his revision of the Ambrysus of Mexico because it was only known from a single male specimen and a key feature used in that work to distinguish the species was the shape of the female SGP. It was not until recently (Reynoso-Velasco 2022), after more than 70 years since the original description, that the female of A. sonorensis was described and the identity of the species clarified.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	description	Variation. Some females exhibit the posterior margin of the SGP with indistinct posterolateral corners. Additionally, in some females the apical third of the SGP can be wider than average, giving it a subquadrate shape.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	materials_examined	Type locality. Mexico: Sonora: Mpio. Álamos, Río Mayo at San Bernardo. Repository. Male holotype (Fig. 38) is housed at the CAS. Published records: MEXICO: Sinaloa, Sonora (Reynoso-Velasco 2022).	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	distribution	Distribution. This species is distributed in the northwestern part of Mexico, predominantly in the drainage systems with headwaters in the western slopes of the Sierra Madre Occidental mountain range, in the states of Sinaloa and Sonora (Fig. 39). The majority of records are within the northernmost section of the Pacific Lowlands biogeographic province (160 – 570 meters). A single record situated farthest north is in the Chihuahuan Desert province (1,300 meters) and another in the Sierra Madre Occidental province (1,231 meters). Some localities are in the vicinity of the border with the state of Chihuahua, where the drainage systems in which the species was collected originate; thus, the species most likely is also present in the southwesternmost part of this state.	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	materials_examined	Type material examined. HOLOTYPE ♂ (by original designation). MEXICO: Sonora: [Mpio. Álamos], San Bernardo, Rio Mayo, 02 - III- 1935, H. S. Gentry coll. Additional material examined. MEXICO: Sinaloa: [Mpio. Choix], Rio Choix at Choix, [26 º 43 ’ 58.31 ’’ N, 108 º 18 ’ 52.06 ’’ W], 24 - IV- 1981, CL 1643, J. T. & D. A. Polhemus / J. T. Polhemus Collection 2014 / C. J. DrakeAccession (1 ♀ USNM). Sonora: Mpio. Álamos, Arroyo El Taymuco at El Naranjo, 27 ° 14 ’ 43.3 ’’ N, 108 ° 45 ’ 27.8 ’’ W, 462 m, L- 1682, 25 - XII- 2013, Reynoso-Velasco coll. (2 ♂, 3 ♀ IEXA); Mpio. Álamos, Arroyo La Vinatería at Taymuco (El Vado), 27 ° 14 ’ 39.7 ’’ N, 108 ° 43 ’ 17.3 ’’ W, 537 m, L- 1683, 25 - XII- 2013, Reynoso-Velasco coll. (2 ♂, 2 ♀ IEXA; 9 ♂, 1 ♀ UMC); Mpio. Álamos, Río Mayo at Nahuibampo, 27 ° 22 ’ 28.8 ’’ N, 108 ° 54 ’ 34.4 ’’ W, 158 m, L- 1685, 26 - XII- 2013, Reynoso-Velasco coll. (1 ♂, 1 ♀ UMC); [Mpio. Álamos], Upper Rio Mayo [N of San Bernardo, 27 º 25 ’ 30.14 ’’ N, 108 º 51 ’ 26.74 ’’ W], 19 - IV- 1981, CL 1636, J. T. & D. A. Polhemus / J. T. Polhemus Collection 2014 / C. J. Drake Accession (1 ♂, 1 ♀ USNM); [Mpio. Bacanora] Rio Bacanora at Bacanora, [28 º 58 ’ 50.02 ’’ N, 109 º 23 ’ 45.90 ’’ W], 24 - IV- 1982, D. A. & J. T. Polhemus colls. / J. T. Polhemus Collection 2014 / C. J. Drake Accession (7 ♂, 5 ♀ USNM); [Mpio. Imuris], 9 mi NNE of Imuris, [30 º 52 ’ 36.41 ’’ N, 110 º 44 ’ 09.39 ’’ W], 7 – 11 - VII- 1958, J. D. Alcorn coll. (2 ♂, 2 ♀ SEMC); Mpio. Onavas, Arroyo Tepoca at Tepoca, 28 ° 25 ’ 50.3 ’’ N, 109 ° 15 ’ 26.0 ’’ W, 564 m, L- 1691, 27 - XII- 2013, Reynoso-Velasco coll. (2 ♂, 2 ♀ CNIN; 19 ♂, 18 ♀ IEXA; 12 ♂, 10 ♀ UMC); [Mpio. Rosario de Tesopaco], Arroyo Batella [Río Nuri], on Hwy 11 at junct to Nuri, [28 º 06 ’ 38.25 ’’ N, 109 º 19 ’ 17.07 ’’ W], 18 - I- 1988, Kondratieff coll. / J. T. Polhemus Collection 2014 / C. J. Drake Accession (1 ♂ USNM); Mpio. Rosario de Tesopaco, Arroyo Cajón de Amador ca. 6 km N of Nuri, 28 ° 09 ’ 50.0 ’’ N, 109 ° 19 ’ 37.7 ’’ W, 324 m, L- 1689, 27 - XII- 2013, Reynoso-Velasco coll. (2 ♂, 5 ♀ IEXA; 1 ♂ UMC); [Mpio. San Pedro de la Cueva], Rio Moctezuma, trib. Rio Yaqui, 2 mi N of Batuc, [29 º 16 ’ 50.20 ’’ N, 109 º 44 ’ 03.61 ’’ W], 16 - III- 1941. R. G. Miller coll. (1 ♂ UMMZ); [Mpio. Yécora], Arroyo Milpillas [El Encinal] at Tepoca on Hwy 16, [28 º 25 ’ 48.36 ’’ N, 109 º 15 ’ 26.31 ’’ W], 550 m, 20 - IV- 1988, CL 2317, D. A. & J. T. Polhemus colls. / J. T. Polhemus Collection 2014 / C. J. Drake Accession (1 ♂, 1 ♀ USNM); [Mpio. Yécora, Río Pedregoso at] 22 mi NE of Yécora, [28 º 22 ’ 33.36 ’’ N, 108 º 45 ’ 38.69 ’’ W], 26 - IV- 1982, D. A. & J. T. Polhemus colls. / J. T. Polhemus Collection 2014 / C. J. Drake Accession (3 ♀ USNM). A. guttatipennis Stål species complex [1]	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	description	A. bispinus La Rivers, 1953 Guatemala and Mexico A. bowlesi Reynoso & Sites, 2016 Mexico A. contrerasi Reynoso & Sites, 2016 Mexico A. drakei La Rivers, 1957 Mexico	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
912A944AEB34FFDAFF71FBB0ADB151CF.taxon	description	A. noveloi Reynoso & Sites, 2016 Mexico A. veracruzanus Reynoso & Sites, 2016 Mexico A. hybridus Montandon species complex [2]	en	Reynoso-Velasco, Daniel, Sites, Robert W. (2025): Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3. Zootaxa 5735 (1): 1-66, DOI: 10.11646/zootaxa.5735.1.1, URL: https://doi.org/10.11646/zootaxa.5735.1.1
