Australambrysus minutus Rodrigues, Canejo & Sites, 2024

Rodrigues, Higor D. D., Canejo, Rafael P. R. & Sites, Robert W., 2024, New species, new combinations, and morphological notes of South American Ambrysinae (Heteroptera: Naucoridae), Zootaxa 5447 (2), pp. 199-224 : 206-207

Australambrysus minutus Rodrigues, Canejo & Sites NEW SPECIES urn:lsid:zoobank.org:act:0323294C-CB5F-4DFE-BAEB-02BCC38EB490

( Figs. 4 , 13 )

Description. Macropterous female. HOLOTYPE, length 6.24; maximum width 3.20. General shape elongate, parallel-sided; widest across embolia. Overall dorsal coloration brown, head, lateral margins of pronotum and legs slightly lighter ( Fig. 4A ). Dorsal surface coarsely punctate. Ventrally light-brown, except anterolateral and posteromedial areas of propleuron dark-brown ( Fig. 4B ).

Head. Length 1.12; maximum width 1.36. Brown, with dark-brown spot along midline between eyes converging anteriorly, coarsely punctate. Eyes convergent anteriorly, flat and not raised above level of vertex or pronotum, synthlipsis 0.72. Anterior margin between eyes slightly convex, nearly straight, extending anteriorly in front of eyes 7% of head length; posterior margin between eyes strongly convex, extending posteriorly 39% of head length. Labrum width 1.46× length, evenly rounded, with sparse long hairs. Maxillary plate developed anteriorly forming slight projection beyond anterior margin of head. Labium with three visible segments, basal two segments yellowish, distal segment brown, extending 0.36 beyond labrum. Antennal proportions 4:10:16:10, length 0.40, elongate hairs on segment IV and posterior half of III.

Thorax. Pronotum coarsely punctate; transverse sulcus marking anterior border of transverse band in posterior 1/4; brown with lateral margins and medial V-shaped area lighter; lateral margins shallowly convex, strongly convergent anteriorly; posterior margin straight medially, slightly lobed posteriorly laterally; anterior margin deeply concave to embrace convex posterior margin of head and eyes; posterolateral corners rounded ( Fig. 4A ); width 2.92× length; length at midline 1.00; maximum width at posterolateral corners 2.92. Propleuron with glabrous band along lateral margin in posterior half, narrow anteriorly, then widening abruptly and gradually narrowing posteriorly; apices of propleura meeting broadly at midline, separated from level of prosternellum; propleuron with inner margin near procoxa and medial half of posterior margin with elongate golden setae. Probasisternum yellowish, with sharp medial carina with row of setae lateral to carina. Scutellum brown with lighter mottling and coarsely punctate, triangular, width 2× length, width 1.92, length 0.96. Hemelytra coarsely punctate, except membrane and posterior narrow stripe between membrane and embolium. Claval commissure length 0.72. Embolium length 2.04, greatest width 0.40; lateral margin nearly straight in anterior 3/4, shallowly convex posteriorly, yellow anteriorly, becoming brown posteriorly. Hind wings well-developed. Mesobasisternum with midventral longitudinal tumescence with sulcus on midline; tumescence terminating posteriorly as acute mesosternellum. Metasternellum (= metaxyphus) subtriangular, with apex acute.

Legs. All segments yellow, except prothoracic legs brown. Profemur dorsally coarsely punctate; anterior margin with dense pad of setae. Protibia and tarsus with occlusal surface flattened and with spatulate setae; tarsus immovable, one-segmented; pretarsal claw single, minute, triangular. Meso- and metacoxae partially recessed into thorax, with broad longitudinal sulcus that can accommodate flexed femora. Meso- and metafemora with row of short, brown spines on anterior margin; spines restricted to basal half on mesofemur, nearly full length on metafemur. Meso- and metatibiae with ventrolateral, ventromedial, dorsolateral, and dorsomedial rows of stout reddish-brown spines; meso- and metatibiae with one comb row of reddish-brown spines at apical rim dorsolaterally, and two comb rows at apical rim ventrally. Meso- and metatibiae and -tarsi with long with long, pale swimming hairs; hairs profuse on metatibia and -tarsus. Meso- and metapretarsi with paired claws slender, curved, without basal tooth. Leg measurements as follows: fore leg, femur 1.68, tibia 1.32, tarsus 0.36; middle leg, femur 1.64, tibia 1.52, tarsomeres 1–3, 0.10, 0.18, 0.28; hind leg, femur 1.76, tibia 2.08, tarsomeres 1–3, 0.12, 0.26, 0.40.

Abdomen. Dorsally with segments III–VII exposed; yellowish-brown anteriorly, brown posteriorly; lateral margins smooth, with short recurved pale hairs, group of trichobothria near posterolateral corners. Posterolateral corners of II (visible ventrally) –V narrowly rounded to right-angled, not spinose, VI bluntly acute. Ventrally yellowish, slightly darker on laterosternites, with pile of fine hairs. Longitudinal band of elongate golden hairs beginning on midline of III and widening posteriorly to anterior 1/3 of VII (subgenital plate). Lateral margin with thin, glabrous band. Glabrous patches on laterosternites II–VII ( Fig. 4B ). Left laterosternite VI with strong, posteriorly directed acuminate, digitate lobe in middle of posterior margin, lobe absent on right side. Mediosternite VII (subgenital plate) with posterior margin concave at midline, rounded posterolateral lobes, and sinuate lateral margin ( Fig. 4H ); subgenital plate width 1.19 length; length at midline 0.63; maximum width 0.75.

Macropterous male. Paratypes (n = 2), length 5.88–5.96 (mean = 5.92); maximum width 3.12–3.20 (mean = 3.16). Similar to female in general structure and coloration, except as follows: Tergum V asymmetrical, with posterior margin displaced slightly to left. Tergum VI asymmetrical; accessory genitalic process with mesal margin angled and not broadly prolonged laterally ( Fig. 4C ). Medial lobes of VIII (pseudoparameres) with apical margin broadly rounded ( Fig. 4D ). Phallosoma elongate, linear, with right side angled at apical 1/3 ( Fig. 4F ); ventrally with pair of lobes weakly sclerotized, both with small papillae ( Fig. 4G ). Parameres symmetrical, ovate, mostly covered with numerous elongate setae originating on posterior half, extending mesad. Pygophore with elongate setae sparsely distributed over most of surface, with thick brush of elongate setae on posterior margin ( Fig. 4F ).

Hind wing brachypterous male. Paratypes (n = 2), length 5.92–6.16 (mean = 6.04); maximum width 3.28. Similar to macropterous male in general structure and coloration, except as follows: Callosity on left anterior margin of pronotum (probably result of mutation). Pronotum posterolateral corner broadly rounded. Claval suture faint in anterior half, suppressed posteriorly.

Comparative notes. Australambrysus minutus n. sp. is morphologically similar to A. brunneus (Sites, 2015) and A. shorti (Sites, 2015) , two species that also occur in northern South America. These three species share small body sizes, ranging from 5.88 to 8.04 mm, the propleura are not tightly appressed to the probasisternum and prosternellum, the posterolateral corners of the abdominal segments are not spinose, and the parameres have a dense brush of setae on the dorsal surface extending mesad. The female of A. brunneus has the posterior margin of laterosternite VI with a strong, posteriorly directed acuminate, digitate lobe, on each side of the segment. The female of A. minutus has the same feature, however, on the left side only ( Fig. 4H ). Although we found no trace that the digitate process on the right side was broken, this possibility cannot be excluded. In A. minutus , the dorsal color of the body is brown ( Fig. 4A ), the body length varies from 5.88 to 6.24, the accessory genitalic process of male abdominal tergum VI has the medial margin angled ( Fig. 4C ), and the pseudoparameres of male abdominal tergum VIII are rounded ( Fig. 4D ), whereas in A. brunneus , the dorsal color of the body is dark-brown, the body length varies from 7.56 to 8.04, the accessory genitalic process has the medial margin shallowly convex, and the pseudoparameres are subrectangular to oval (see Sites 2015; Sites et al. 2017). In relation to A. shorti , A. minutus can be easily distinguished by the morphology of the accessory genitalic process and phallosoma (see Sites 2015).

Distribution. Both records of this new species are located in the northern side of the Amazon Basin, in the states of Roraima and Amazonas, northern Brazil ( Fig. 13 ).

Etymology. The specific epithet minutus , from Latin (= little, small), is in reference to the small body size of this species, uncommon within Ambrysinae .

Type material. HOLOTYPE ♀ macropterous ( INPA), BRAZIL, Amazonas, Serra do Aracá, Igarapé do Cobra , B08, 00°52’34.2”N, 63°27’03.6”W, 157 m, 28.VII.2009, PT928, N. Hamada, A.M.O. Pes, R.L. Ferreira-Keppler, C.A.S. Azevêdo & C. Monteiro col. PARATYPES: same data as holotype (2♂ macropterous INPA) ; same data except no elevation, Folhico de Correnteza (1♂ brachypterous UMC) . Roraima, [Área Indígena Yanomami], Serra de Surucucu , [02º49’53.78”N, 63º38’19.78”W], igarapé sem nome, 1655, “H-I”, 28.XI.1991, V. Py-Daniel & U. Barbosa col. (1♂ brachypterous MZUSP) .

Figures

FIGURE 4. Australambrysus minutus n. sp., (A) dorsal and (B) ventral habitus of male holotype (INPA), (C) 6th and 7th abdominal terga of male, (D) 8th abdominal tergum of male, (E) genital capsule of male, (F) genital capsule with proctiger removed, (G) ventral surface of phallosoma, (H) terminal abdominal sterna of female, arrow indicates digitate lobe at posterior margin of left laterosternite VI. Size bars = 1 mm and applies only to Figs. A–B.

FIGURE 13. Distribution records for South American species of Ambrysinae (Naucoridae). Imprecise localities (e.g., only the state is known) are displayed as question marks.