Triportheus culter ( Cope, 1872 )

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 186-188

Triportheus culter ( Cope, 1872)

Fig. 14

Chalcinus culter Cope, 1872:265 (description; type locality not mentioned).

Coscinoxyron culter . Fowler, 1907:450-451 (description; t y p e s p e c i e s o f t h e n e w g e n u s Coscinoxyron ). Eigenmann & Allen, 1942:262 (designation as type species of the new genus Coscinoxyron ).

Triportheus culter . Géry, 1977:343 (key; upper Amazon).

Chalcinus elongatus iquitensis Nakashima, 1941:64 (type not seen), Iquitos , Peru.

Diagnosis. An elongate Triportheus species reaching 245 mm SL (depth at dorsal-fin origin, 20.6-25.9, mean = 22.6% SL, n = 13; depth at pectoral-fin insertion, 23.9-28.5, mean = 26.1% SL, n = 13). The presence of 1 longitudinal scale row between the pectoral-fin insertion and the midventral keel distinguish this species from all deep-bodied Triportheus species all of which that have 2 longitudinal scale rows between the pectoral-fin insertion and the ventral keel. The combination of the number of lateral-line scales (43-47, mean = 45.1, n = 12) and number of gill rakers on the lower limb of the first gill arch (53-83, mean = 70.7, n = 13) distinguishes T. culter from all other elongate-bodied Triportheus species.

Description. Morphometric data for Triportheus culter presented in Table 10. 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; slightly slanted, nearly straight from nares to rear of head. Dorsal profile of body gently convex, almost straight from rear of head to dorsal-fin origin; posteroventrally slanted along dorsal-fin base; less inclined from posterior terminus of dorsal-fin base to caudal peduncle; slightly concave along caudal peduncle.

Ventral profile of head vertically straight from dorsal border 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; slightly curved to nearly straight from that point to anal-fin origin; posterodorsally slanted along anal-fin base; slightly concave along caudal peduncle. Prepelvic region expanded, with midventral keel.

Head pointed in profile; snout straight, slightly blunted in profile. Mouth terminal; slightly upturned; lower jaw equal to upper jaw. Nostrils of each side close together; anterior opening circular; posterior kidney-shaped. Eye large, without adipose eyelid.

PROOFS

Opercle posteriorly expanded, its posterior margin reaching vertical through pectoral-fin insertion. Gill rakers thin and close together, gill-rakers as long as length of branchial filaments; gill rakers on lower limb of first gill arch 53-83 [62] (mean = 70.7, n = 13).

Teeth on premaxilla in two rows somewhat irregular giving appearance of 3 rows; teeth of inner row larger. Outer row formed by 6 pentacuspidate teeth. Six teeth on inner row; second tooth from symphysis smaller than other teeth in series. Maxilla with 2 teeth smaller than smallest premaxilla tooth. Teeth on lower jaw in two rows, with 5-6 teeth with 5-7 cusps on outer row; inner row consisting of 1 conical symphyseal tooth.

Scales cycloid, thin, large. Lateral line distinctly decurved ventrally, completely pored from supracleithrum to base of caudal-fin rays. Forty-three to 47 (mean = 45.1, n = 12) scales in lateral line; 7 scale series between lateral line and dorsal-fin origin; 2 scale series between lateral line and pelvic-fin insertion. One large scale between pectoral-fin insertion and midventral keel; 18-22 scales along mid-dorsal line between tip of supraoccipital process and dorsal-fin origin. Four rows of scales on caudal peduncle.

Dorsal-fin rays ii,9; anal-fin rays iii,28-32 [32] (mean = 29, n = 13); pectoral-fin rays i,11-13 [12]; pelvic-fin rays i,6. Dorsal-fin base situated on posterior one-half of the body; base of last dorsal-fin ray located along vertical through first anal-fin ray. Pectoral fin long, reaching posteriorly to vertical through tip of pelvic fin. First branched anal-fin ray longest; following rays rapidly decreasing in length.

Caudal fin emarginate, covered by scales only basally. Middle caudal-fin rays terminate at posterior margin of remainder of fin.

Total vertebrae 40 [40].

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

Distribution. Rio Amazonas basin ( Fig. 12 ).

Type-material examined. Triportheus culter : holotype, ANSP 16672 ,130 mm SL, Peru, río Ampiyacu , John Hauxwell.

Type-locality and type-material remarks. Cope (1872:265) did not furnish a catalog number for the type of Chalcinus culter and provided only the following information about that specimen: “Total length. 158 m.; length to dorsal fin.087, to anal.098.” The locality of collection is referred only in the introduction, in a general reference to the fishes listed in his paper. According to Cope the collection includes fishes from small tributaries of the río Ampiyacu, collected by John Hauxwell, and some additional species collected by Robert Perkins in an expedition from the mouth of rio Negro to the río Ucayali. The holotype and only specimen used by Cope was subsequently cited as ANSP 16672 by Fowler (1907:450) and Böhlke (1984:45). This specimen is cited as having been collected in Equador (= Ecuador), by J. Hauxwell, in a locality that is now within Peru. It is a very damaged specimen but has 62 gill rakers (a count typical of T. culter ).

No type was designated for Chalcinus elongatus iquitensis Nakashima, 1941 . The synonym of the species into Triportheus culter herein is based on combination of characters presented in the description: number of lateral line scales (46) and gill rakers (“branquiespinas”, 16+62).

Non-type material. Brazil: Amazonas: USNM 229129 (1), lago Terra Preta (4°12’S, 59°57’W) ; INHS 72547 (1), lago Terra Preta, Januari (4°12’S, 59°57’W) ; MZUSP 6068 (1), Manaus, rio Preto da Eva (3°6’S, 60°1’W) ; USNM 352932 (1 of 2), lago de Coari (4°8’S, 63°20’W) . Rondônia: MZUSP 14047 (4), rio Machado lago Jacundá (9°6’S, 62°48’W) . Peru: Loreto: MZUSP 26438 (1), Supay-cocha (6°16’S, 74°48’W) ; INHS 43246 (1), río Napo , 103 km NE Mazari (3°28’S, 72°45’W) ; MUSM 12653 (2), Maynas, rio Amazonas, Quistococha (3°0’S, 73°39’W) ; MUSM 12683 (1), Maynas, rio Amazonas, Quistococha (3°49’S, 73°16’W) .

Figures

Fig. 14. Triportheus culter, INHS 43246, 100.62 mm SL, Peru, río Napo, 103 km NE Mazari.

Fig. 12. Map of central and northern South America showing geographic distribution of T. culter (circles; asterisk = type-locality), T. albus (squares; asterisk = type-locality), T. nematurus (triangles; diamond = type-locality) and T. venezuelensis (lozenges; white square = type-locality) (some symbols represent more than one locality or lot of specimens).