Triportheus auritus (Valenciennes in Cuvier & Valenciennes, 1850)

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 178-179

Triportheus auritus

(Valenciennes, in Cuvier & Valenciennes, 1850) Fig. 7

Chalcinus auritus Valenciennes , in Cuvier & Valenciennes, 1850:262-263 (description).

Triportheus auritus . Fowler, 1950:357 (synonymy; Brazil, Amazonas, rio Araguaia).

Chalcinus elongatus Günther, 1864:342 (description; typelocality: “?”).

Triportheus elongatus . Fowler, 1945:153 (listed with synonyms, for Peru).

Chalcinus cruzi Miranda-Ribeiro, 1941: 173 (description, Brazil, rio Amazonas).

Chalcinus amazonensis Miranda-Ribeiro, 1941:174 (description, Brazil, no type-locality)

Diagnosis. An elongate Triportheus species reaching 242 mm SL (depth at dorsal-fin origin, 22.5-28.8 % SL; depth at pectoral-fin insertion, 24.8-32.0 % SL). The presence of 1 longitudinal scale row between the pectoral-fin insertion and ventral keel distinguish this species from all deep-bodied Triportheus species that have 2 longitudinal scale rows between the pectoral-fin insertion and ventral keel. Triportheus auritus is distinguished from all elongate and deep-bodied Triportheus species by the combination of the small number of gill rakers on the lower limb of first gill arch (22-28, mean = 24.8, n = 39) and the high number of lateral-line scales (40-46, mean = 43.9, n = 36).

Description. Morphometric data of Triportheus auritus presented in Table 6. Body elongate and compressed laterally. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. Dorsal profile of head slightly convex from upper lip to nares; nearly straight from nares to rear of head. Dorsal profile of body nearly straight from rear of head to dorsal-fin origin; posteroventrally slanted along dorsal-fin base; less inclined from posterior terminus of dorsal fin to caudal peduncle; slightly concave along caudal peduncle. Dorsal portion of body transversely rounded.

Ventral profile of head vertically straight from dorsal border of lower lip to anteroventral margin of dentary; straight from that point to joint with quadrate. Ventral profile of body arched from isthmus to pelvic-fin insertion; slightly curved to nearly straight from that point to analfin origin; posterodorsally slanted along anal-fin base; slightly concave along caudal peduncle. Prepelvic region ventrally expanded with midventral keel; kell extending to anal-fin origin.

Head pointed in profile. Mouth terminal; lower jaw as long as upper jaw. Nostrils of each side close together; anterior opening circular; posterior kidney-shaped. Eye large, without adipose eyelid.

Gill rakers thick and separated, gill-raker length about one-half length of branchial filament; gill rakers on lower limb of first arch 22-28 [25] (mean = 24.8, n = 39).

Teeth on premaxilla in 3 rows; teeth of inner row larger. Outer row formed by 5 pentacuspidate teeth; middle row with 2 teeth, inner row with 6 teeth. Maxilla with 2-4 teeth, smaller than smallest teeth on premaxilla. Teeth on lower jaw in 2 rows with 5-6 teeth with 5-7 cusps in outer row and inner row consisting of single conical symphyseal tooth.

Scales cycloid, thin, and large. Lateral line distinctly decurved ventrally, completely pored from supracleithrum to base of caudal-fin rays. Forty to 46 [43] (mean = 43.9, n = 36) scales in lateral line; 6 scale series between lateral line and dorsal-fin origin; 2 scale rows between lateral line and pelvic-fin insertion. One large scale row between pectoral-fin insertion and midventral keel; 14-20 [19] (mean = 17.6, n = 31) scales along mid-dorsal line between tip of supraoccipital spine and dorsal-fin origin. Five rows of scales on caudal peduncle.

Dorsal-fin rays ii,9; anal-fin rays iii,24-28 [28] (mean = 26.2, n = 39); pectoral-fin rays i,11-13 [11] (mean = 11.9, n = 39); pelvic-fin rays i,6. Dorsal-fin margin straight, dorsal-fin base situated on posterior one-half of body; base of last dorsal-fin ray located anterior to vertical through anal-fin origin. Pectoral large, extending posteriorly as far as mid length of pelvic fin. First branched anal-fin ray longest; following rays rapidly decreasing in length. Caudal truncate, scaled only at base. Middle caudal-fin rays extended slightly beyond posterior margin of remainder of fin.

Total vertebrae 43-44.

Distribution. Rio Amazonas, Tocantins, and Araguaia basins, río Orinoco basin, Trinidad ( Fig. 8 ).

Remarks about type-specimens. Cuvier & Valenciennes (1849:263) noted that “[the length of our fish is six pounces. The specimens deposited in the collection of the museum were collected in the Amazon by Mr. Castelnau] (my translation). No specimens identified as Chalcinus auritus with these data were located in the holdings of MNHN (where the specimens were supposed to belong). A neotype collected in the rio Amazonas drainage (MZUSP 58859, rio Negro, Anavilhanas), is designated herein for Triportheus auritus . That species as defined herein best fits the original description by Valenciennes, in terms of overall body and head shape, and counts of the lateral-line scales and anal-fin rays.

Coloration in alcohol. Overall ground color yellowish brown. Snout, lower lip, and dorsal portion of head dark. Scattered dark chromatophores present on all head bones. Body with mid-lateral dark stripe extending from supracleithrum posteriorly to caudal peduncle; stripe becoming diffuse posteriorly and broadened into distinctly wider diffuse dark spot on lateral surface of caudal peduncle. Body darker brown dorsal to midlateral stripe. Dorsal margin of body dark. All fins pigmented along rays. Dorsal and pectoral-fin rays outlined by dark chromatophores. Distal tips of anal-fin rays darker. Caudal-fin rays outlined by series of dark chromatophores.

Type-material examined. Triportheus auritus : Neotype by present designation, MZUSP 58859, 185.9 mm SL, Brazil, Amazonas, rio Negro , Anavilhanas, M. Goulding, Oct 1979 (2°42’S, 60°45’W).

Chalcinus elongatus : holotype, BMNH 1852.9.13 :10, no locality. Günther (1864:342) in the original description of Chalcinus elongatus refers to the type-material as being “From the Collection of the Zoological Society” and the distribution as “Hab.—?”. A specimen identified as the holotype of Chalcinus elongatus is housed in BMNH ( BMNH 1852.9.13:10) .

Chalcinus amazonensis : holotype, MNRJ 2771 , rio Amazonas, M. Lobato .

Chalcinus cruzi : holotype, MNRJ 2775 , South America , O. Cruz .

Non-type material. Brazil: Amazonas : USNM 229127 (2), near Manaus, lago Janauari, lago Canta Galos (3°12’S, 60°1’W) ; USNM 307147 (3), Ressaca da Ilha de Marchantaria (4°4’S, 59°7’W) ; USNM 307137 (1), lago Canta Galos, lago Janauari (3°12’S, 60°1’W) ; USNM 311094 (1), rio Solimões between Manaus and Tefé (3°22’S, 64°41’W) ; USNM307103 (1), paraná da Ilha de Marchantaria (4°4’S, 59°7’W) ; INHS 71472 (4), lago Janauari about 8 km SW Manaus (3°12’S, 60°1’W) ; INHS 73035 (3), lago Marchantaria, Camaleão inlet, Marchantaria Island , about 12 km S Manaus (4°4’S, 59°7’W) ; INHS 67386 (2), lago Canta Galos off lago Janauari , about 8 km SW Manaus (3°12’S, 60°1’W) ; USNM 307117 (2), Ressaca da Ilha de Marchantaria (4°4’S, 59°7’W) ; USNM 307139 (3 of 8), Ressaca da Ilha de Marchantaria (4°4’S, 59°7’W) ; MZUSP 19768 (9), lago Janauacá. Mato Grosso : MCP s/n (3), rio Araguaia, Barra do Garças (16°20’S, 52°41’W) . Pará : FMNH 56501 (1), Santarém (0°57’S, 46°59’W) . Goiás: MCP 17212 (5), Rio Araguaia near Luis Alves (13º14’S, 50º35’W) . Equador: Napo: FMNH 103056 (10), río Yasuni, Laguna Jatuncocha (1º0’S, 75º29’W) . Guiana: FMNH 7496 (1), Morawhanna (8°16’N, 59°45’W) . Peru: Loreto: USNM 280625 (1), green water caño on left bank of río Manite, about 8 km upriver of junction of río Manite and rio Amazonas (3°31’S, 72°40’W) ; USNM 280493 (1), río Nanay approximately 20 km upstream of mouth, main channel, side channels and side pools (3º51’S, 73º1’W) ; USNM 280508 (1), río Itaya , main river channel and lower portions of caños, 5 to 20 km upstream of Belen, Iquitos (3º51’S, 73º12’W) ; USNM 280492 (1), Quebrada Corrientillo, at Corrientillo, on road running West From Iquitos to río Nanay (3º50’S, 73º13’W) . USNM 280494 (2), canyons entering río Nanay, Northeast of Iquitos (3º49’S, 73º11’W) ; NRM 30491 (1), río Itaya drainage, Quisto Cocha, W lake margin, (3º50’S, 73º16’W) ; NRM 30487 (1), rio Nanay drainage, Bella Vista, Vieja Cocha . INHS 39760 (1) lago Pabellon, río Orosa, Amazonas drainage, 40 min from Paucarillo (03º44’S, 72º25’W) ; INHS 40370 (6), río Nanay Amazonas drainage, Pampa Chica, N edge of Iquitos (03º44’S, 73º16’W) ; INHS 38943 (1 of 9), Iquitos dock at Requena , (03º44’S, 73º14’W) ; USNM 176118 (1), Caño Shansho, Ampyacu (4°6’S, 72°59’W) . Trinidad: USNM 229911 (5), Chatham at river mouth about 100 m upstream (10°53’N, 61°52’W) . Venezuela: Delta do Amacuro : USNM 233639 (6), río Orinoco, small side caño, caño Araguao, 112 Naut. mi upstream from sea buoy (8º38’N, 61º43’W) ; AMNH 217731 (5), North side río Orinoco , caño on isla Guacujana, S shore. Amazonas : FMNH 103902 (1), Río Orinoco ca. 5 h above Atabapo by falca (4°2’N, 67°42’W) ; INHS 29146 (1), río Mavaca (2°31’N, 65°11’W) ; AMNH 93061 (1), río Mavaca , 45 min up river from base camp (2°31’N, 65°11’W) . Monagas: FMNH 55905 (1), La Pedrita ; USNM 233227 (2), isolated lagoon on isla Tapatapa, at Los Castillos, 163 Naut. mi from sea buoy (8°31’N, 62°26’W) . Bolívar: UMMZ 211304 (4), small canyons on the west side of río Arature , several km upstream from mouth, Orinoco drainage (8º35’N, 60º53’W) ; INHS 35088 (1), laguna Castillero, near río Orinoco (7º38’N, 66º9’W) ; INHS 35220 (1), laguna Castilhero (7º38’N, 66º9’W) . Guarico: INHS 34483 (1), río San Bartolo at Aguas Muertas (8º4’N, 66º40’W) . Apure: INHS 61491 (2), Cano San Miguel, río Cinaruco (6º 4’N, 67º17’W) . Anzoategui: INHS 29281 , laguna Orsinera (8º9’N, 63º34’W) . INHS 29267 (1), laguna las Tejitas (8º9’N, 63º26’W) .

Figures

Fig. 7. Triportheus auritus, neotype, MZUSP 58859, 185.9 mm SL, Brazil,Amazonas, rio Negro, Anavilhanas.

Fig. 8. Map of central and northern South America showing geographic distribution of Triportheus auritus (circles; asterisk = neotype locality), T. guentheri (black squares; white square = type-locality) and T. curtus (triangle; diamond = syntype-localities) (some symbols represent more than one locality or lot of specimens).