Triportheus rotundatus (Jardine in Schomburgk, 1841 )

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 174-175

Triportheus rotundatus (Jardine in Schomburgk, 1841)

Fig. 3

Chalceus rotundatus Jardine in Schomburgk, 1841:209-10 (drawing; type-locality: river Padauiri). Günther, 1864:341 (as synonym of Chalcinus brachypomus ). Eigenmann & Eigenmann, 1891:56 (as synonym of Chalcinus angulatus ). Eigenmann, 1910:440 (as synonym of Chalcinus güntheri ).

Chalcinus rotundatus . Fowler, 1907:450.

Triportheus rotundatus . Fowler, 1945:154 (listed; Peru (Iquitos), Guayana, Brazil).

Diagnosis. A deep bodied Triportheus species that reaches 178 mm of SL (depth at dorsal-fin origin, 29.7-40.1 % SL; depth at pectoral-fin insertion, 34.0-39.9 % SL). Triportheus rotundatus can be distinguished from other Triportheus species by the combination of the presence of 2 longitudinal scale rows between the pectoral-fin insertion and ventral keel; the number of gill rakers on the lower limb of first arch (24-32, mean = 27.6, n = 37); the number of branched anal-fin rays (25-29, mean = 27.1, n = 37), and number of lateral line scales (28-35, mean = 32.3, n = 35); the presence of longitudinal dark stripes on the lateral surface of the body; and the median caudal rays developed into a slightly projecting extension.

Description. Morphometric data of Triportheus rotundatus presented in Table 4. Body deep and compressed laterally. Greatest body depth located slightly posterior to vertical through insertion of pectoral fin. Dorsal profile of head straight from snout to rear of head. Dorsal profile of body gently curved from rear of head to dorsal-fin origin; posteroventrally slanted from dorsal-fin origin to caudal peduncle; slightly curved along caudal peduncle.

Ventral profile of head straight from tip of lower lip to anteroventral margin of dentary; straight from that point to isthmus. Ventral profile of body arched from isthmus to pelvic-fin insertion; nearly convex from pelvic-fin insertion to anal-fin origin; posterodorsally slanted along anal-fin base; slightly concave along caudal peduncle. Prepelvic region very expanded and compressed, with well defined keel.

Head blunted in profile; posterior margin of opercle not reaching pectoral-fin insertion. Mouth terminal; slightly upturned. Nostrils of each side close together; anterior opening circular; posterior elongate.

Gill rakers thin and close together; length equivalent to one-half of branchial filament length; gill rakers on lower limb of first arch 24-32 [28] (mean = 27.6, n = 37).

Teeth on premaxilla in 3 rows; teeth of inner row largest. Four or 5 tricuspidate teeth in outer row; outer row teeth positioned along external margin of mouth and can be seen externally. Middle tooth row with 3 tricuspidate teeth; 6 multicuspidate teeth on inner tooth row. Teeth on maxilla 2, teeth smaller than those on premaxilla and flattened. Teeth on lower jaw in 2 rows, outer row with 5 large anterior teeth, and 6 smaller posterior teeth. Inner row formed 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. Twenty-eight to 34 [30] (mean = 32.3, n = 35) scales along lateral line; 6 scale series above lateral line; 2-3 [2] scale rows below lateral line. Two scale rows between pectoral-fin insertion and midventral keel; 4-5 scale series on caudal peduncle. Scales along mid-dorsal line irregularly arranged, 6-13 (mean = 9.3, n = 30) between tip of supraoccipital and dorsal-fin origin.

Dorsal-fin rays ii,9; anal-fin rays iii, 25-29 [27] (mean = 27.1, n = 37); pectoral-fin rays i, 11-13 [11] (mean = 11.5, n = 36); pelvic fin rays i,6. Dorsal-fin margin straight, situated on posterior one half of body; last dorsal-fin ray located at vertical through base of third or fourth branched anal-fin ray; first branched ray longest; following rays slightly decreasing in length. Pectoral fin pointed, tip extending to region falling between middle and tip of pelvic fin. Anal fin margin straight, first branched anal-fin ray longest; following rays gently decreasing in length. Margin of caudal fin truncate; median rays extend slightly beyond margin of remainder of fin. Scales cover basal one-third of caudal fin.

Total vertebrae 37.

PROOFS

Coloration in alcohol. Overall ground color yellowish and overlain by guanine. Snout and dorsal portion of the head dark. Scattered dark chromatophores present on opercle and infraorbitals 5 and 6. Body darker dorsally and over anal-fin base and caudal peduncle. Dorsolateral portion of body with 5 or 6 sinuous, brown, longitudinal stripes. Dark chromatophores distributed over all fins. Dorsal-fin rays outlined by dark chromatophores. Chromatophores distributed over pectoral fin between rays; with more intense pigmentation present on first unbranched ray. Anal-fin margin dark. Middle caudal-fin rays very dark.

Distribution. Rio Amazonas drainage ( Fig. 4 ).

Remarks about type specimens. The type material of C. rotundatus is apparently lost. No specimens identified as types of Chalceus rotundatus are listed in the BMNH registers (Anne-Marie Hodges, BMNH; pers. comm.). Chalceus rotundatus was described based on material collected by Schomburgk, the type-locality cited in the original description as the “river Padauari”, an Amazon River tributary near the Guiana-Venezuela border. According to Papavero (1971:304), Schomburgk collected twice in Guyana, between 1834 and 1839, and from 1840 to 1844. During the latter trip he also explored the Orinoco river. Unfortunately, it is not clear where Schomburgk collected and it was not possible to locate a Padauari river in any of the countries Schomburgk traveled. The drawing provided by Schomburgk is almost useless in terms of identifying the species he collected. A specimen collected in the Amazonas basin (MCP 34863, rio Purus , lago Amapá), is herein designated as a neotype for Triportheus rotundatus . This represents the species that best fits in the original description of T. rotundatus as for as overall body shape and number of lateral line scales.

Type-material examined. Triportheus rotundatus : Neotype by present designation, MCP 34863 , 97.83 mm SL, Brazil, Acre, Rio Purus drainage, lago Amapá , UFAC , 20 Dec 2001 (10°2’36”S, 67°50’24”W).

Non-type material. Bolivia: Beni: INHS 37104 (4), Cuneta (borrow pit); INHS 37161 (1), río Moseruna; INHS 37031 (1), río Matos; UMMZ 66469 (4 of 10), Lago Rogoagua and lagoons nearby (13°57’S, 66°58’W); USNM 303124 (2), lago Normandi, 40 km E San Borja (14º55’S, 66º18’W). Brazil: Acre: MCP 34864 (2), same locality as neotype. Amazonas: INHS 73448 (2), lago Janauacá channel between lago Murumuru and Janauacá, about 42 km SW Manaus (3°25’S, 60°16'”W); INHS 65721 (6), lago Janauacá channel between lago Murumuru and Janauacá, about 42 km SW Manaus (3°25’S, 60°16'”W); USNM 307076 (3 of 4), Paraná of Ilha de Marchantaria (4°4’S, 59°7’W); FMNH 56502 (2), Santarém (0°57’S, 46°59’W). Peru: Madre de Dios: USNM 302528 (3) Manu; Cocha Salvador, oxbow lake off río Manu about 1 hour down river from Pakitza (12°16’S, 70°50’W); USNM 317745 (3), Manu, Manu National Park, Pakitza, Cocha Chica, close to Quebrada Pachija; USNM 319303 (2 of 3), Manu, Manu National Park, Pakitza, Río Manu close to Pachija mouth (7°16’S, 76°46’W); USNM 326861 (1), Manu, Manu National Park , Pakitza, Río Manu close to Pachija mouth (7°16’S, 76°46’W); MUSM 4875 (3), Manu, Cocha Salvador (12°16’S, 70°50’W); MUSM 8757 (3), Tambopata, Zona Reservada Tambopata Candano, río de la Torre, Cocha La Torre (12°43’S, 69°11’W).

Figures

Fig. 3. Triportheus rotundatus, neotype, MCP 34863, 97.83 mm SL, Brazil,Acre, rio Purus drainage, lagoAmapá.

Fig. 4. Map of central and northern South America showing geographic distribution of Triportheus rotundatus (circles; asterisk = neotype locality), T. trifurcatus (black squares), T. pictus (triangle; diamond = type-locality) and T. signatus (stars, white square = type-locality) (some symbols represent more than one locality or lot of specimens).