Triportheus pictus ( Garman, 1890 )

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 190-191

Triportheus pictus ( Garman, 1890)

Fig.16

Chalcinus pictus Garman, 1890:5 (description, Brazil, Amazonas, rio Jutaí).

Triportheus pictus . Fowler, 1950:358 (listed, rio Jutahy)

Diagnosis. A deep bodied Triportheus species reaching 107.3 mm of SL (depth at dorsal-fin origin, 34.9-37.1 % SL; depth at pectoral-fin insertion, 35.4-36.6 % SL). The presence of 2 longitudinal scale rows between the pectoral-fin insertion and the ventral keel distinguish this species from elongated body Triportheus species that have 1 longitudinal scale row between the pectoral-fin insertion and the ventral keel. Triportheus pictus differs from all other deep bodied congeners in its lower number of gill rakers on the lower limb of the first gill arch (22-24, mean = 22.8, n = 4), and lower anal-fin ray count (20-21, mean = 20.5, n = 4).

Description. Morphometric data for Triportheus pictus presented in Table 12. Body very deep and compressed laterally. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. Dorsal profile of head straight from posterior border of premaxilla to rear of head. Dorsal profile of body very slightly convex, almost straight, from rear of head to dorsal-fin origin; posteroventrally slanted from dorsal-fin origin to caudal peduncle; straight along caudal peduncle.

Ventral profile of head somewhat anteriorly curved and then nearly straight to isthmus. Ventral profile of body arched from isthmus to pelvic-fin insertion; slightly curved from pel- vic-fin insertion to anal-fin origin; posterodorsally slanted along anal-fin base; straight along caudal peduncle. Prepelvic region ventrally expanded and flattened, with well developed keel.

Head pointed in profile; snout slightly blunted. Mouth terminal; lower jaw as long as upper jaw. Nostrils of each side close together; anterior opening circular; posterior elongate. Posterior margin of opercle falling short of pectoral-fin insertion.

Gill rakers thick and short, length equivalent to half of branchial filament length; gill rakers on lower limb of first arch 22-24 [24] (mean = 22.8, n = 4).

Teeth on premaxilla in 2 rows; teeth of inner row largest. Five or 6 tricuspidate teeth on outer row and 6 multicuspidate teeth on inner row. Maxilla with 0 to 3 small, tricuspidate teeth. Teeth on lower jaw in 2 rows; outer row with 5 teeth with 5-7 cusps; teeth decreasing in size. Inner dentary tooth 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 to 32 scales in lateral line [32] (mean = 31, n = 4); 5 to 6 scale series above lateral line; 2 scale rows below lateral line. Two scale rows between pectoral fin insertion and midventral keel; 5 scale series on caudal peduncle. Scales along mid-dorsal line 11-13 from supraoccipital process to dorsal-fin origin.

Dorsal-fin rays ii,9; anal-fin rays iii,20-21 [20] (mean = 20.5, n = 4); pectoral-fin rays i,13-14 [13]; pelvic-fin rays i,6. Dorsal fin situated on posterior one-half of body; base of last dorsal-fin ray situated anterior to vertical through analfin origin. Dorsal fin margin straight; first branched ray longest. Pectoral fin pointed, tip reaching to vertical falling in region from middle to tip of pelvic fin. Anal-fin margin straight with first branched anal-fin ray longest and following rays gradually decreasing in length. Margin of caudal fin forked; median rays aligned, and not extending beyond margin of remainder of fin. Scales covering basal one-third of caudal fin.

Total vertebrae 36 [36].

Coloration in alcohol. Overall ground color yellowish with silvery regions. Snout, dorsal portion of head and supraorbital regions dark. Some scattered dark chromatophores on opercle and infraorbitals 5 and 6. Longitudinal silver stripe extending from opercle to caudal peduncle. Body dorsal to stripe darkened by chromatophores concentrated in diffuse stripes.

Body darker on area above anal-fin base and on peduncle. Pectoral fins strongly pigmented along rays, with more intense pigmentation on first unbranched ray and along fin margin. Dorsal and anal fins slightly outlined by dark chromatophores. Some dark chromatophores outlining anal-fin rays. Caudal fin with diagonal dark stripe extending from caudal peduncle to posterior limit of dorsal caudal fin lobe.

Distribution. Rio Amazonas basin (Fig. 4).

Type-material remarks. In the original description of Chalcinus pictus Garman (1890:1) cited the material as originating from the Thayer Expedition and deposited in the Museum of Comparative Zoology but did not provide a catalog number for the holotype, referring only to “a specimen from Jutahy”. One MCZ specimen labeled as Chalcinus pictus and collected by the Thayer expedition in the rio Hyutahy [Jutaí] (MCZ 21261) is considered to be the holotype. Features in this specimen (total length, head length, number of lateral line scales) agree with the information in the original description, in particular the very low number of anal-fin rays (20) typical of T. pictus . Higuchi (1996) cites complete data for the Thayer Expedition rio Jutahy site as: 2°43’S, 66°57’W, Sep-Oct 1865, W. James, S. V. Thayer & Talisman collectors.

Type-material examined. Chalcinus pictus : holotype. MCZ 21261 (107.34 SL), Brazil, Amazonas , rio Hyutahy, [rio Jutaí,

Solimões tributary, approx. 2º43’S, 66º57’W] Sep 1865, W. James, S. V. Thayer & Talisman .

Non-type material. Peru: Loreto: INHS 36731 (4), río Nanay, Amazonas drainage, Santa Clara , W of Iquitos (3°28’S, 73°5’W) .

Figures

Fig. 16. Triportheus pictus, INHS 36731, 61.4 mm SL, Peru, Loreto, río Nanay, Amazonas drainage, Santa Clara, W of Iquitos.