Triportheus trifurcatus ( Castelnau, 1855 )

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 180-182

Triportheus trifurcatus ( Castelnau, 1855) Fig. 9

Chalcinus trifurcatus Castelnau, 1855: 70 , Pl. 37, fig. 1, rio Araguaia, Brazil. Günther, 1864:340-341 (synonym of Chalcinus brachypomus ). Garman, 1890:3 (synonym of Chalcinus angulatus ). Eigenmann & Eigenmann, 1891:56 (synonym of Chalcinus angulatus ). Ulrey, 1895:294 (synonym of Chalcinus angulatus ). Eigenmann, 1910:440 (synonym of Chalcinus angulatus ). Fowler, 1950:359 (synonym of T. rotundatus ).

Triportheus trifurcatus . Portugal, 1990:129-135 (redescription, illustration, map).

Diagnosis. A deep bodied Triportheus species reaching 165 mm of SL (depth at dorsal-fin origin, 27.0-36.2 % SL; depth at pectoral-fin insertion, 31.6-39.1 % SL). The presence of 2 longitudinal scale rows between the pectoral-fin insertion and ventral keel distinguish this species from all elongate bodied Triportheus species that have 1 longitudinal scale row between the pectoral-fin insertion and the ventral keel. Triportheus trifurcatus differs from other deep-bodied Triportheus species by the combination of the number of gill rakers on the lower limb of the first gill arch (40-47, mean = 42.1, n = 24); the number of lateral line scales (32-35, mean = 32.8, n = 20); and the 5 scale series dorsal to the lateral line.

Description. Morphometric data for Triportheus trifurcatus presented in Table 7. Body deep and compressed laterally. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. 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.

orly. Inner row consisting of one conical symphyseal tooth.

Scales cycloid, thin, large. Lateral line distinctly decurved

ventrally, completely pored from supracleithrum to base of

caudal-fin rays. Thirty-two to 35 (mean = 33.8, n = 20) scales

in lateral line; 5 scale series above lateral line; 2-3 scale rows

below lateral line. Two scale rows between pectoral-fin inser-

tion and midventral keel; 4-5 scale series on caudal peduncle.

Nine to12 scales (mean = 10.2, n = 20) along mid-dorsal line

from supraoccipital process to dorsal-fin origin.

Dorsal-fin rays ii,9; anal-fin rays iii-iv, 26-29 (mean = 27.3,

n = 24); pectoral-fin rays i,10-12; pelvic-fin rays i,6. Dorsal-

fin base located on posterior one-half of body with last dor-

sal-fin ray located at vertical line through base of third or Ventral profile of head straight from PROOFS tip of lower lip to est rays fourth Anal-fin reaching; following decreasing anal-fin margin posteriorly rays ray slightly straight; gradually first to area in, branched first length middle decreasing branched. Pectoral ray and longest anal-fin in tip fin length of pointed; pelvic following ray. Margin long-, fin tip. anteroventral margin of dentary; straight from that point to of caudal fin truncate; median rays extend about one-half isthmus. Ventral profile of body arched from isthmus to pel- their length beyond margin of remainder of fin. Scales covvic-fin insertion; nearly convex from pelvic-fin insertion to ering basal one-third of fin. anal-fin origin; posterodorsally slanted along anal-fin base; Total vertebrae 37. slightly curved along caudal peduncle. Prepelvic region ventrally expanded and flattened, with well defined keel. Coloration in alcohol. Overall ground color yellowish silvery. Head blunt in profile; posterior margin of opercle reach- Snout and dorsal portion of head dark. Scattered dark chroing pectoral-fin insertion. Mouth terminal; lower jaw as long matophores present on opercle and infraorbitals 5 and 6. Body as upper jaw. Nostrils of each side close together; anterior darker dorsally and dorsal to anal-fin base and on caudal opening circular; posterior elongate. peduncle. Five or 6 sinuous, brown, longitudinal stripes Gill rakers thin and close together, almost so long as present on dorsolateral portion of body. Dark chromatophores branchial filament length; gill rakers on lower limb of first distributed over all fins. Dorsal-fin rays outlined by dark chroarch 40-47. matophores. Chromatophores distributed over pectoral-fin Teeth on premaxilla in 3 rows; teeth of inner row largest. between the rays; more intense pigmentation present on first Five tricuspidate teeth on outer row; outer row teeth arranged unbranched ray. Anal-fin margin darker. Middle caudal-fin along margin of mouth and can be seen externally in closed rays very dark.

Distribution. Rio Tocantins and rio Araguaia drainages (Fig. 4).

Type-material remarks. The type material of Chalcinus trifurcatus consists of a dry specimen ( MNHN A 9837 ). Measurements of the holotype presented in Table 7 are fairly accurate. They were obtained from a radiograph of that specimen .

Type-material examined. Chalcinus trifurcatus : holotype, MNHN A 9837, 136.29 mm SL, (dry specimen, only radiograph examined), Brazil, Pará, Araguaya, collected by Castelnau.

Non-type material. Brazil: Goiás: MZUSP 4832 (21 of 36), rio Araguaia, Aruanã (14°53’S, 51°4’W) . Tocantins: MZUSP 52122 (3), Araguaçu, rio Água Fria in the road between Araguaçu and Barreira do Piqui , 27 km North to Araguaçu (12°43’S, 49°55’W) . Mato Grosso: MZUSP 19633 (3), rio Araguaia, Santa Terezinha (10°35’S, 50°34’W) . Pará : MZUSP 20640 (5), Tucuruí, rio Tocantins, below Tucuruí lake in the margin of igarapé Espírito Santo (3°46’S, 49°41’W) .

Figures

Fig. 9. Triportheus trifurcatus, MZUSP 19633, 165 mm SL, Brazil, Mato Grosso, rioAraguaia, Santa Terezinha.