Hypoptopoma incognitum, Aquino & Schaefer, 2010

Aquino, Adriana E., 2010, Systematics Of The Genus Hypoptopoma Günther, 1868 (Siluriformes, Loricariidae), Bulletin of the American Museum of Natural History 2010 (336), pp. 1-110 : 70-76

Hypoptopoma incognitum , new species Figure 36 , table 13

HOLOTYPE: AMNH 39759 , 85.01 mm SL, female, Bolivia: Beni, Río Itenez, opposite to Costa Marques ; collected by R.M. Bailey and R. Ramos, 1–3 September 1964.

PARATYPES (collected with holotype): AMNH 241976, 6 females and 13 males, 2 cs, 76.6–94.1 mm SL. UMMZ 204339, 8 females and 8 males, 3 cs, 79.56–95.03 mm SL.

OTHER MATERIAL EXAMINED: BOLIVIA, Beni: AMNH 40039 (1 ³, 85.4 mm SL) Río Baures, above mouth 6 km SW Costa Marques, Brazil ; AMNH 77403 (1 ³, 72.1 mm SL) Río Mamore´, ca. 10 km west of San Pedro ; AMNH 77467 (2 ♀ + 1 ³, 43.5–57.3 mm SL) Río Mamore´, Puerto Siles ; CAS 77140 (1 ³, 56.7 mm SL) Cachuela Esperanza , first falls of the Beni ; CBF 1323 (5 ♀, 53.1–78.9 mm SL) Ballivian, Espíritu, Arroyo Carnaval , Río Yacuma , Mamore´ , Madeira ; USNM 305596 (2 ♀, 47.2–49.2 mm SL) Río Matos / Apere / Mamore´ ; Prov. Ballivia, Río Matos below road x-ing, 48 km E San Borja. Pando: FMNH 107001 (2 ♀, 48.0– 62.3 mm SL) 100 m de la boca del Nareuda en el Tahuamanu ; FMNH 107002 (2 ♀, 36.4– 39.1 mm SL) Río Nareuda, río arriba de la desembocadura en el Tahuamanu ; FMNH 107003 (7 ♀, 41.8–71.1 mm SL) Río Manuripi, +/2 12 km río arriba de Puerto Rico ; FMNH 107004 (2 ♀ + 2 ³, 54.5–71.5 mm SL) Río Manuripi, +/2 20 km río arriba de Puerto Rico ; FMNH 107007 (1 ♀, 71.3 mm SL) Brazo del Manuripi , +/2 1 km río arriba del campamento ; FMNH 107008 (8 ♀, 50.2– 70.6 mm SL) Río Manuripi above camp ; FMNH 107009 (3 ♀ + 2 ³, 52.8–82.1 mm SL) Río Manuripi at playa, 5.78 km from camp, 9.23 from Puerto Rico ; FMNH 107010 (2 ♀ + 2 ³, 65.1–73.6 mm SL) Río Manuripi at playa outside, 6.76 km above camp and 9.78 above Puerto Rico ; FMNH 107011 (1 ♀, 34.6 mm SL) Rio Manuripi at island 0.76 km above camp and 4.20 above Puerto Rico. Santa Cruz: CBF 2862 (1 ♀, 53.9 mm SL) Guarayos , Perseverancia , Río Negro cerca de Las Naranjas ; CBF 10110 (1 ♀, 51.1 mm SL) Guarayos, Perseverancia ,

TABLE 13

Morphometric Data for Hypoptopoma incognitum Holotype: AMNH 39759 . Paratype: AMNH 241976 . Nontypes: CAS 6736 , 6748 , 56723 ; FMNH 117743 ;

INPA 2798, 6039; MUSM 7520, 10521; MZUSP 4978; UMMZ 202339; USNM 177706, 177707, 308093.

Río Negro. BRAZIL, Acre: MZUSP 49782 (3 ♀ + 1 ³, 45.5–46.9 mm SL) Rio Acre, entre Seringal Paraiso y Lago Amapa ; MZUSP 49795 (1 ♀ + 1 ³, 75.2–85.7 mm SL) Lago Amapa. Amazonas: CAS 56723 (1 ♀, 74.0 mm SL) Igarapé Chibareno, 30 km E of Manaus on south shore of Rio Negro , about 0.3 mi. S of its entrance into Rio Amazonas ; INPA 127 (4, 51.3–70.4 mm SL) Lago Janauaca, Rio Solimões ; INPA 807 (1 ♀, 84.0 mm SL) Flutuante do Tarumã Açu ; INPA 2798 (9 ♀ + 4 ³, 2 cs, 58.9–88.3 mm SL) Ihla da Marchantaria, Rio Solimões ; INPA 2800 (1, 74.1 mm SL) Lago Janauaca, Rio Solimões ; INPA 6035 (3 ♀, 82.0– 85.6 mm SL) Rio Amazonas, Ihla do Careiro, Lago do Pedro ; INPA 6082 (1 ³, 78.8 mm SL) Rio Solimões , Boca do Paraná do Janauacá ; INPA 6088 (1 juvenile, 58.8 mm SL) Río Madeira, Igarapé Aramaguara ; INPA 14017 (1 ³, 76.2 mm SL) Rio Solimões , Parana do Rei ; MZUSP 6723 (1 ♀, 74.1 mm SL) Rio Negro, Manaus ; MZUSP 7557 (1 ♀ + 1 ³, 64.9–68.2 mm SL) Parana do Urucura, mun. de Urucura ; MZUSP 7654 (1 ♀, 75.5 mm SL) Boca do lago José Açu, Parintins ; MZUSP 6598 (1 ♀, 74.4 mm SL) Lago Manacupuru ; MZUSP 27607 (1 ♀, 67.0 mm SL) Paraná de Capacete, Rio Solimões, mun. de Benjamin Constant ; MZUSP 36198 (1 ♀, 90.0 mm SL) Lago Janauaca e arrededores, Rio Solimões ; MZUSP 36227 (1 juvenile, 43.3 mm SL) Ihla Marchantaria , perto de Manaus ; USNM 177706 (1 ♀, 62.3 mm SL) Amazonas, Rio Urubu ; USNM 177707 (1 ♀, 65.95 mm SL) Amazonas, Rio Urubu ; USNM 306963 (2 juveniles, 37.3–41.0 mm SL) ressaca da Ilha de Marchantaria ; USNM 306991 (1 juvenile, 41.8 mm SL) ressaca da Ilha de Marchantaria ; USNM 307056 (1 ³, 62.24 mm SL) Amazonas, Paraná de Janauaca, entrada do Lago Castanho ; USNM 308093 (1 ³, 82.9 mm SL) Amazonas, entrada de Janauari, entre Furo de Paracuuba e Lago Terra Preta ; USNM 308244 (1 ³, 83.2 mm SL) near Manaus, entrance of lago Janauari , between furo (channel) de Paracuuba and lago Terra Preta ; USNM 308303 (1 ³, 79.0 mm SL) Amazonas, Lago Terra Preta, Janauari. Goiás: MZUSP 4881 (11, 39.2– 71.0 mm SL) Rio Araguaia , Aruana. Maranhão: MNRJ 17720 (8) Rio Mearim em Arari ; MNRJ 17725 (4) Rio Mearim ; MNRJ 17726 (1) Lago Malhada Grande. Mato Grosso: MZUSP 36222 (1 juvenile, 47.6 mm SL) Río Araguaia, Santa Terezinha. Pará : CAS 6736 (1 ♀, 70.3 mm SL) Amazonas , Santarém market ; CAS 6748 (1 ♀, 92.4 mm SL) Amazonas, Santarém market ; FMNH 59622 (3 ♀, 47.0– 55.6 mm SL) Santarém ; FMNH 117743 (13 ♀ + 2 ³, 41.6–72.3 mm) Santarém ; INPA 558 (2) Rio Tocantins, Ig. Arapari, Breu Branco ; INPA 6028 (1) Rio Tocantins, Breu Branco ; INPA 6029 (1) Rio Tocantins, Poco do Paulo ; INPA 6030 (1) Rio Tocantins, Breu Branco, Igarape Arapari ; INPA 6031 (2) Rio Tocantins, Breu Branco, Igarape Canoal ; INPA 6032 (1) Rio Tocantins, Breu Branco, Igarape Arapari ; INPA 6033 (3) Rio Tocantins, Itupiranga ; INPA 6036 (5) Rio Tocantins, a jusante da represa ; INPA 6037 (1) Rio Tocantins, Breu Branco, Igarape Canoal ; INPA 6039 (13) Rio Tocantins, Itupiranga ; INPA 6053 (9) Rio Tocantins, Igarape Arapari, Breu Branco ; INPA 6054 (1) Rio Tocantins, Icangui ; INPA 6055 (2) Rio Tocantins, Capuerana ; INPA 6057 (1) Rio Tocantins, Tucurui, Igarape Vallentim ; INPA 6058 (1) Rio Tocantins, Itupiranga ; INPA 6059 (1) Rio Tocantins, Breu Branco, Igarape Canoal ; MHNG 2538 12 (1 ♀, 48.1 mm SL) Ig. Azul, Ilha do Cameta, face a Santarém ; MHNG 2708.060 (1 ³, 71.7 mm SL) Amazon river , side arm with lagos along right shore, about 10 km downriver of Santarém ; MZUSP 5657 (6 juveniles, 19.1–39.8 mm SL) Lago Paru, Oriximiná ; MZUSP 7850 (3 ♀, 63.5–69.7 mm SL) Parana Jacare´, Mun. Faro ; MZUSP 8539 (1 ♀, 76.7 mm SL) Rio Tapajos, Santarém ; MZUSP 34194 (1 ♀, 89.6 mm SL) Tocantins, Tucurui ; MZUSP 36185 (1 ♀, 71.7 mm SL) Rio Arari , Cachoeira de Arari, Ilha de Marajo ; MZUSP 36186 (2 ♀, 57.2– 80.4 mm SL) Lagoa marginal do Rio Tocantins, perto de Baiao ; MZUSP 36188 (1 ♀, 64.9 mm SL) Oriximiná. Rondonia: INPA 456 (16 ♀ + 9 ³, 63.0–75.0 mm SL) Río Madeira, Varza de calama, Lago de Repartimento ; INPA 2237 (1 ♀, 70.0 mm SL) Río Madeira, Calama Flechal. Roraima: INPA 49 (1 ♀, 86.1 mm SL) Paraná do Rio Branco. PERU, Madre de Dios: ANSP 144008 (1 ♀, 65.9 mm SL) NW of Puerto Maldonado, Lago Tupuhumaro, oxbow lake E bank of Madre de Dios, above junction with Río de las Piedras ; MUSM 2474 (5 ♀, 40.6– 66.6 mm SL) Manú, Parque Nacional, Pakitza , Cocha Salvador ; MUSM 7520 (1 ♀ + 5 ³, 33.2–65.8 mm SL) Tambopata, Río Madre de Dios, Lago Valencia ; MUSM 7960 (1 ♀, 55.1 mm SL) Tambopata, Río Madre de Dios, Lago Valencia ; MUSM 8123 (3 ♀, 60.2–65.2 mm SL) Tambopata, Candamo, Río Tambopata , Río Chuncho ; USNM 263910 (3 ♀, 46.4–69.6 mm SL) Reserva Natural de Tambopata, Laguna Cocococha , 5.1 km to E of explorers inn ; USNM 264046 (2 juveniles, 35.9–44.5 mm SL) Reserva Natural de Tambopata, Laguna Chica , end opposite boat dock (farthest from trail leading to lodge) ; USNM 302696 (6 ♀ + 1 ³, 2 cs, 40.3–68.1 mm SL) Prov. Manú, Coche Salvador, and oxbow lake off Río Manú about 1 hr. downriver from Pakitsa ; USNM 327324 (3 ♀, 50.0– 56.5 mm SL) Prov.Manú, Parque Nacional Manú, Cocha Salvador ; USNM 327333 (1 ♀ + 1 ³, 49.4– 71.2 mm SL) Prov. Manú, Parque Nacional Manú, Cocha Nueva ; USNM 327334 (2, 58.3–63.5 mm SL) Prov. Manú, Parque Nacional Manú, Río Manú , Cocha Juárez ; USNM 327340 (1 ♀ + 1 ³, 48.8–55.0 mm SL) Prov. Manú, Parque Nacional Manú, Cocha Nueva. Ucayali: MHNG 2407.97 (2 ♀, 68.8– 76.0 mm SL) Bagazan , Río Ucayali, Pucallpa ; MUSM 10476 (2 ♀, 44.6–47.6 mm SL) Purús, Río Purús, Cocha Zapote ; MUSM 10521 (10 ♀ + 5 ³, 44.7–77.1 mm SL) Purús, Río Purús, Cocha Bola de Oro ; USNM 384194 (1 ♀, 44.8 mm SL) Río Purús .

DIAGNOSIS: Hypoptopoma incognitum is distinguished from all congeners, with the exception of H. elongatum , by the presence of a patch of odontodes on the anterolateral surface of the cleithrum at the opening to the branchial chamber. Hypoptopoma incognitum is distinguished from H. elongatum by having a shorter caudal peduncle (caudal-peduncle length 26.0–36.0 (32.0) vs. 32.3–36.3 (34.4); ttest, p, 0.001) (fig. 37); by a deeper, more robust caudal peduncle (caudal-peduncle depth 8.8–11.0 (10.1) vs. 7.9–8.8 (8.4); t-test, p, 0.001); by the round to slightly acute snout (vs. snout appearing pointed due to slight lateral inflexion between rostral plate and first infraorbital); by fewer plates along medial series (21–22 (22) vs. 23); by having caudal-fin lobes light brown (vs. caudal-fin lobes dark).

DESCRIPTION: Morphometric and meristic data presented in table 13. Body robust; greatest body depth at dorsal-fin origin. Dorsal profile of head and body straight from tip of snout to dorsal-fin origin, slightly elevated at posterior supraoccipital tip; straight from dorsal-fin origin to anteriormost procurrent caudal-fin ray. Ventral profile slightly convex from tip of snout to anteriormost procurrent caudal-fin ray. Head moderately depressed, almost as wide as cleithral width; lateral process of lateral ethmoid bone visible dorsally. Snout rounded to slightly acute in dorsal view; dorsally, slightly concave anterior to naris. Posterior surface of bony pit of nasal organ sharply inclined. Trunk cross section between pectoral- and pelvic-fin origin slightly triangular, ovoid to progressively rounded posterior to dorsal fin, progressively compressed posteri- or to adipose-fin base.

Eyes relatively large, positioned closer to posterior tip of compound pterotic than to tip of snout. Ventral margin of orbit located on ventral surface of head. Dorsal interorbital distance/ventral interorbital distance ratio changing from,1 to.1 during ontogeny.

Total plates in lateral medial series 21–22 (22). Dorsal series plates 19; middorsal series plates 4; midventral series plates 12–14 (13), three plates anterior to first ventral series plate; ventral series plates 19. Second plate of midventral series contacting two plates of medial series.

Abdomen covered by paired series of lateral sickle-shaped plates, with unequal number of plates between left and right sides, 4–8 each; anterior azygous plate usually present; medial abdominal plates, if present, not forming well-defined series. Single anal plate present. Thoracic plates present, 2–6 (4). Preopercular canal in preopercle present, semicircular; anteriormost pore opening between ventral canal-bearing plate and fourth infraorbital; framed by notch at posterolateral margin of canal-bearing plate and ventral margin of fourth infraorbital.

Small odontodes evenly distributed on head. Odontodes along anterior snout margin not arranged in well-defined series, without odontode-free discontinuity between ventrad and dorsad odontodes. Odontodes along dorsal snout margin small, slightly larger than those on dorsal surface of head. Lamina of trunk plates with odontodes arranged in longitudinal rows, becoming progressively smoother ontogenetically; marginal odontodes present in mature adults. Patch of odontodes on anterolateral surface of cleithrum, at opening to branchial chamber, visible upon retraction of branchiostegal membrane. Odontode patch variably developed, from few odontodes to elevated patch of closely arranged odontodes; expression of patch often bilaterally variable.

Total vertebrae 26. Premaxillary teeth 18– 23 (21); dentary teeth 17–20 (18). Maxillary barbels short, extended slightly beyond anterior margin of ventral canal-bearing plate in adults.

Dorsal-fin origin located slightly posterior to vertical through pelvic-fin origin. Depressed pectoral fin reaching to anus; pectoral-fin spine with serrae along posterior margin, individual serrae oriented orthogonal to spine shaft. Extension of serrae along pectoral spine margin reduced ontogenetically from proximal two-thirds in smaller specimens to middle third in larger specimens. Pectoral fin reaching to vertical through midpoint between pelvic-fin tip and anal-fin origin. Pelvic fin short with unbranched and first branched rays equal in length. Depressed fin reaching beyond anus, not reaching to anal-fin origin. Caudal-fin margin concave to forked; upper and lower lobes equal. Adipose fin present or absent; when present, composed of bony spine shaft and membrane; when absent, small platelike scar visible.

COLOR IN ALCOHOL: Ground color tan and pale ochre. Melanophores light to dark brown on trunk; melanophores on head and trunk varying from uniformerly distributed to clustered in beanlike spots; melanophores slightly more concentrated along narrow area between compound pterotic, cleithral process, and anterior margin of opercle, at base of dorsal and pectoral fins, and on anterior surface of lip. Deep-lying melanophores arranged in series of blotches posterior to dorsal-fin base. Midlateral stripe situated mostly along medial plates series. Ventral surface of body mostly unpigmented except for scattered melanophores on posterior portion of trunk, anterolateral margin of cleithra, cleithral process, canal-bearing plates, and lateral portions of lateral abdominal series. Paired, dorsal and anal fins with dark brown bands. Dorsal fin with dark triangular spot extended over base of anterior 3–4 branched rays. Series of lanceolate plates at caudal-fin base darkened by black melanophores. Basal triangular spot on caudal fin variably present, typically absent. Caudal fin pigmentation pattern typically composed of three broad bands, with distal tip of lobes light brown. Juveniles up to around 60 mm SL with slightly different caudal-fin pigmentation, having a small triangular spot at base of lower lobe, followed by darker broad bar and darker tips of dorsal and ventral lobes.

SEXUAL DIMORPHISM: Male urogenital papilla well developed, pointed, joined at base to anterior flaplike anus. Males with patch of tightly arranged small odontodes oriented as a swirl, variably covering first to fourth plates of ventral series, lateral to urogenital papilla. Female anus tubular, without separate urogenital papilla. In females, size and arrangement of odontodes on plates lateral to anus similar to adjacent plates, without distinct patch of differentially arranged odontodes.

COMPARISONS: The overall pattern of morphometric variation between Hypoptopoma incognitum and H. elongatum is summarized by the results of a sheared principal component analysis on 20 morphometric characters (fig. 38; table 14). The second and third components represent 35.1 % and 1.6 % of the variation of the morphometric data, respectively; the separation between species is complete along PC2. The analysis shows that the morphometric variance is expressed mostly by variables related to the elongation of the body (trunk and caudal peduncle length, caudal-peduncle depth, and snout length).

DISTRIBUTION: Broadest distribution among species of Hypoptopoma across the central and lower Rio Amazonas basin. It is found in the Rio Tocantins basin and is the only species known for northeastern coastal rivers (fig. 39).

ETYMOLOGY: The specific epithet incognitum (Lt. incognitus, meaning ‘‘unknown, strange’’) is a reference to the fact that speci- mens of the species have long been misidentified with other species of Hypoptopoma .

Hypoptopoma steindachneri Boulenger, 1895

Figures

Fig. 36. Hypoptopoma incognitum, holotype, AMNH 39759, 85.01 mm SL, female, in dorsal, lateral, and ventral views.