Triportheus curtus ( 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 : 191-192

Triportheus curtus ( Garman, 1890)

Fig. 17

Chalcinus angulatus curtus Garman, 1890:4 (diagnosis; described as subspecies of C. angulatus ; type-locality: Brazil, “Pará and Arary”).

Triportheus angulatus curtus . Fowler, 1940:101 (listed; Bolívia, Laguna Rogagua, Cachuela Esperanza, Rurrenabaque).

Triportheus curtus . Portugal, 1990:159-165 (description; synonymy list; illustration; map,).

Diagnosis. A deep-bodied Triportheus species reaching 106.8 mm of SL (depth at dorsal-fin origin, 33.5-36.2; depth at pectoral-fin insertion, 35.5-39.5 % SL). The presence of 2 longitudinal scale rows between the pectoral-fin insertion and the ventral keel distinguishes this species from elongate-bodied Triportheus species that have 1 longitudinal scale row between the pectoral-fin insertion and the ventral keel. Triportheus curtus 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 (23-28, mean = 25.8, n = 4); the number of lateral-line scales (32-34); the number of branched anal-fin rays (24-28, mean = 25.0, n = 4); the head length (24.6- 29.4, mean = 28.4% of SL); the distance from the snout to the anal-fin origin (74.5-75.9, mean = 75.2% of SL); and the analfin base length (23.1-24.5, mean = 23.9% of SL).

Description. Morphometric data of Triportheus curtus presented in Table 13. Body very deep and compressed laterally. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. Dorsal profile of head straight from margin of premaxilla to rear of head. Dorsal profile of body very slightly convex, from rear of head to dorsal-fin origin; posteroventrally slanted from dorsal-fin origin to caudal peduncle; straight along caudal peduncle. Dorsal portion of body slightly keeled.

Ventral profile of head curved from tip of lower lip to isthmus. Ventral profile of body arched from isthmus to pelvic-fin insertion; slightly curved from pelvic-fin insertion to anal-fin origin; posterodorsally slanted along analfin base; straight along caudal peduncle. Prepelvic region very expanded ventrally and flattened, with well developed keel.

Head pointed in profile; snout slightly rounded. Mouth dorsally oriented; lower jaw equals to upper jaw. Nostrils of each side close together; anterior opening circular; posterior elongate. Posterior margin of opercle reaching to vertical through pectoral-fin insertion.

Gill rakers thick and spaced, length equivalent to three quarters of branchial filament length; gill rakers on lower limb of first arch 23-28 [27-28].

Teeth on premaxilla in 2 rows; teeth of inner row larger. Outer row teeth irregularly arranged with 5 or 6 tricuspidate teeth. Six multicuspidate teeth on inner row in premaxilla. Maxilla with 0 to 3 small, tricuspidate teeth. Teeth on lower jaw in 2 rows, outer row with 5 teeth with 5-7 cusps, tooth size decreasing posteriorly. Inner dentary row consisting of 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 34 scales in lateral line [32-34]; 5 scale series above lateral line; 2 scale rows below lateral line. Two scale rows between pectoralfin insertion and midventral keel; 5 scale series on caudal peduncle. Scales along mid-dorsal line very irregular, 6- 13 [13-14] from supraoccipital process and to origin of dorsal fin.

Dorsal-fin rays ii,9; anal-fin rays iii,24-28 [26-28]; pectoral-fin rays i,11-13 [11]; pelvic-fin rays i,6. Dorsal fin situated on posterior one-half of body; base of last dorsal-fin ray located at vertical line running through base of fourth or fifth branched anal-fin ray; second unbranched and first branched ray longest; following rays gradually decreasing in length. Pectoral fin pointed, reaching vertical falling within area between middle and tip of pelvic fin. Anal-fin margin straight, first branched anal-fin ray longest; following rays gradually decreasing in length. Margin of caudal fin truncate; median rays extended beyond margin of remainder of fin. Scales cover basal one-third of fin.

Total vertebrae 36-37 [37].

Coloration in alcohol. Overall ground color yellowish with silver regions. Some small, dark spots scattered over body.

Distribution. Rio Amazonas basin ( Fig. 8 ).

Type-material remarks. Garman (1890:1) cited the material that served as the basis of his description of Chalcinus angulatus curtus as being collected by the Thayer Expedition and deposited in MCZ. Garman did not list the type of his subspecies but 3 specimens identified as the syntypes of Chalcinus angulatus curtus (MCZ 21272 (2), MCZ 21264 (1)) are in the MCZ collections.

Type-material examined. Chalcinus angulatus curtus : syntype, MCZ 21272 (1 of 2), 70.9 mm SL, Brazil, Pará , lago Arari, Ilha de Marajó (0º20’S, 49º10’W), L. Agassiz, 1-5 Mar 1866. MCZ 21264 (1) , syntype, 106.8 mm SL, J. Couto de Magalhães , 19-21 Aug 1865 [01°10”S, 49°00”W] .

Non-type material. Peru: Ucayali: MUSM 6978 (4), Purus, río Curanja, Cocha Grau (09º57’S, 70º59’W) .

Figures

Fig. 17. Triportheus curtus, MUSM 6978, 51.12 mm SL, Peru, Ucayali, río Curanja, Cocha Grau.

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).