Bryconamericus ecai, Silva, 2004

Silva, José Francisco Pezzi da, 2004, Two new species of Bryconamericus Eigenmann (Characiformes: Characidae) from southern Brazil, Neotropical Ichthyology 2 (2), pp. 55-60 : 58-59

Bryconamericus ecai , new species

Fig. 3

Holotype: MCP 19608 (60.6 mm SL, male) creek in Linha Brasil, parallel to the road from Vila Deodoro to Venâncio Aires (tributary to arroio Castelhano , rio Taquari , laguna dos Patos drainage) (approx. 29 o 33’S 52 o 17’W), Venâncio Aires, Rio Grande do Sul, Brazil, 14 October 1994, Z. M. S. Lucena, C. A. S. Lucena & J. F. Pezzi da Silva.

Paratypes: MCP 17494, (75, 7 c&s, 13.6-75.1 mm SL), collected with the holotype .

Diagnosis. Bryconamericus ecai differs from other Bryconamericus species by the combination of body depth (33.1- 36.9% of SL, mean 34.9, versus up to 31.0% in B. lambari ; B. patriciae ; B. stramineus ; and B. exodon ) eye diameter (31.1- 33.9% of HL, mean 32.3, versus 35.4-42.8%, mean 39.0 in B. iheringii ); snout length (26.8-32.4% of HL, mean 29.6 versus 20.1-24.6%, mean 22.2 in B. rubropictus ); branched anal-fin rays (15-18 versus 18-20 in B. ikaa ; 19-22 in B. agna ; and 22- 25 in B. sylvicola ); and teeth of inner row of premaxilla tricuspid or pentacuspid (versus heptacuspid in B. uporas ); teeth compressed distally (versus teeth massive in B. microcephalus , B. ornaticeps , and B. tenuis ); males with bony hooks on pelvic and anal fins (males without bony hooks on pelvic and anal fins in B. menni and B. pyahu ).

Description. Morphometric data summarized in Table 1 . Body laterally compressed. Greatest body depth at dorsal fin origin. Dorsal body profile slightly convex from tip of supraoccipital to dorsal-fin origin, nearly straight from posterior dorsal-fin base to adipose fin, and gently concave from adipose fin to caudal-fin origin. Ventral body profile convex from isthmus to anal-fin origin, straight along anal-fin base, and gently concave from posterior anal-fin base to caudal fin.

Mouth sub-terminal, lower jaw shorter than upper jaw. Snout profile rounded from margin of upper lip to vertical through anterior nostrils, nearly straight from that point to supraoccipital. Ventral profile of head gently convex. Premaxilla with two series of teeth with three to five cusps, central cusp largest, teeth with same size in both series. Inner row with four teeth, 3 to 5 in outer row. Dentary with 8 to 10 teeth. Anterior 4 to 5 dentary teeth largest, with 3 to 5 cusps, with 3 to 5 posterior teeth becoming progressively smaller, tricuspid or conical. Maxilla with 3 to 4 teeth, with 3 to 5 cusps, approximately equal in size.

Dorsal-fin rays ii,8. First unbranched dorsal-fin ray about half length of second unbranched ray. Dorsal fin posterior border straight; it tip not reaching adipose fin when depressed. Dorsal-fin origin approximately at mid-length of body. Adipose-fin origin located slightly anterior to vertical through insertion of last anal-fin ray. Anal-fin rays iii-iv,15-18 (iii,18). Anal fin origin slightly anterior to vertical through insertion of last dorsal-fin ray. Distal border of anal fin slightly concave. Last unbranched to 7th branched anal-fin rays with few, tiny bony hooks, one pair per segment. Up to 16 hook pairs per ray, usually 10-13. Hooks present in posterolateral surface of ray. Females without hooks on anal fin. Pectoral-fin rays i, 10- 12 (i, 11), distal margin slightly rounded, not reaching pelvicfin origin. Pelvic-fin rays i, 6-7 (i, 7), distal margin straight, not reaching anal fin origin. Pelvic-fin origin slightly anterior of vertical through dorsal-fin origin. Male pelvic fin with thin bony hooks, more elongate than anal bony hooks, present in ventromedial surface of each ray, with one hook per segment, absent on unbranched ray. Females without hooks on pelvic fin. Caudal fin forked, lobes rounded, equal in size, not scaled. Principal caudal-fin rays 19; 11-12 procurrent rays dorsally and 10-12 ventrally.

Scale cycloid. Anal fin with a single row of 7-10 (8) scales covering base of anteriormost rays. Lateral line complete, 36- 38 (37) scales; 5-6 (5) scales in transverse series from dorsalfin origin to lateral line; 4 scales between lateral line and analfin origin. Predorsal scales 12-14 (13) sometimes in irregular series. Scales around caudal peduncle 14. Vertebrae: precaudal 16-17; caudal 18-19. Supraneurals 4-6 (in six c&s specimens).

Color in alcohol. Ground color tan. Dorsal portions of head and body region above midlateral stripe more pigmented. Dark midlateral stripe, more conspicuous posterior to vertical through distal border of pectoral fin, expanded into faint, small horizontally elongate spot on caudal peduncle, not reaching upper and lower margins of caudal peduncle and extending on base of caudal fin rays. Two humeral spots, first, vertically elongate, centered on third or fourth scales of pored lateral line and extended two series above; second spot more diffuse, without clearly marked limits. Pectoral and pelvic fins hyaline. Dorsal, anal, and caudal fin with scattered dark chromatophores

Etymology. From the Tupi-Guarani eçai , meaning small eye,

in allusion to the smaller eye diameter in comparison to other Bryconamericus species.

Distribution. So far known from the type-locality a creek tributary of the lower portion of rio Taquari (laguna dos Patos drainage), Rio Grande do Sul, Brazil.

Habitat. Bryconamericus ecai was found in a creek with clear to turbid water, light to moderate water current and bottom with stones and sand.

Figures

Fig. 3. Bryconamericus ecai, holotype, MCP 19608 (60,6 mm SL, male), lateral view.