Hyphessobrycon scutulatus, Lucena, 2003

Lucena, Carlos Alberto Santos de, 2003, New characid fish, Hyphessobrycon scutulatus, from the rio Teles Pires drainage, upper rio Tapajós system (Ostariophysi: Characiformes: Characidae), Neotropical Ichthyology 1 (2), pp. 93-96 : 94-95

Hyphessobrycon scutulatus , new species Fig. 1

Holotype. MCP 33333 (male, 34.73 mm SL): Brazil, Mato Grosso: rio Kaiapá, MT 320 road, about 5 km from Nova Canaã do Norte, rio Teles Pires drainage, rio Tapajós system, 10 o 36’16”S, 55 o 42’26”W; 22 Jan 2002, V. Bertaco, A. Cardoso, L. Malabarba, E. Pereira & R. Reis.

Paratypes. MCP 32356 (129, 28 counted and measured, 27.55- 34.99 mm SL; 16 females, 27.55-34.99 mm SL and 12 males, 31.46-32.83 mm SL), collected with the holotype . MCP 33729 (13, 27.44-29.10 mm SL; 7 c&s, 26.81-32.96 mm SL, one male 26.81 mm SL) probably from rio Kaiapá , rio Teles Pires drainage, 22-23 Jan 2002 , V. Bertaco, A. Cardoso, L. Malabarba, E. Pereira & R. Reis .

Diagnosis. Differs from all Hyphessobrycon species by the following characters: 7 to 8 tricuspid teeth in the inner premaxillary tooth row; 5 to 9 tricuspid teeth in maxilla; 18 to 21 anal-fin branched rays; small dark spot centered on the basal portion of the median caudal-fin rays, sometimes extending to their distal portions; humeral spot and longitudinal stripe absent; male pelvic fins with hooks; hooks, sometimes present in the anal fin.

Description. Measurements given in Table 1 . Body compressed, relatively slender; greatest body depth at

dorsal-fin origin. Predorsal profile slightly convex, slightly concave at nape. Dorsal profile nearly straight from dorsal-fin base to just posterior to adipose fin; caudal peduncle dorsal profile slightly concave between adipose fin and dorsal procurrent caudal-fin rays. Dorsal-fin origin distance from snout tip nearly equal or smaller than its distance to anal-fin base. Ventral body profile slightly convex from lower jaw to anal-fin origin; straight along anal-fin base; nearly straight along caudal peduncle. Mouth terminal. Maxilla short, reaching vertical line tangent to anterior border of eye. Obliquus superioris muscle very thin in humeral region with aspect of false pseudotympanum.

Premaxilla with two tooth rows; external row with 3 tricuspid teeth (2 to 4, mean = 2.6, n = 30); inner row with 8 tricuspid teeth (7 to 8, 3 specimens with 8, n = 36). Maxilla with 9 tricuspid teeth (5 to 9, mean = 6.3, n = 35); most posterior one or two teeth sometimes conical. Dentary with 15 teeth (12 to 15, mean = 13, n = 7 c&s); 5 to 7 anterior teeth larger and tricuspid, followed by 5 to 8 progressively smaller conical teeth.

Dorsal-fin rays ii,9 (n = 36). Adipose fin present. Anal-fin rays iii,19 (iii,18-21, mean = 19.0, n = 36), third unbranched, first and second branched rays longer in both males and females. One c&s male with very small hooks numbering 5 in first, 1 in third and 1 in fourth branched rays. Pectoral-fin rays i,10 (i,10-12, mean = 10.5, n = 36); distal tips not reaching pelvic fin. Pelvic-fin rays i,7 (n = 36); males with small hooks along posterior border of rays; usually one hook per bony ray segment, rarely two. Principal caudal-fin rays i,17,i (n = 36).

Lateral line perforated scales 7 (7-9, mean = 7.3, n = 26). Longitudinal series of scales, including perforated scales, 32 (30-35, mean = 32.0, n = 21). Scale rows between lateral line and pelvic-fin origin, 4 (3.5-4 scales, mean = 4.0, n = 29). Scale rows between lateral line and dorsal-fin origin, 6 (5-6, mean = 5.9, n = 16). Scale rows around caudal peduncle, 14 (13-15, mean = 13.6, n = 17).

Vertebrae 37 (38 in one specimen), 14-15 precaudal and 17-18 caudal (n=7). Upper gill rakers 3 (3-5, mean = 4.0, n = 35), lower gill rakers 9 (9-11, mean = 9.5, n = 35).

Color in alcohol. Body light brown. A narrow dark line along midbody, from caudal spot to near humeral region, not reaching humeral region in some specimens. Lateral body scales above midlateral line and dorsal scales from supraoccipital process through dorsal procurrent caudalfin rays bordered with black chromatophores forming reticulate pattern. Small dark spot at middle caudal-fin base, either extending or not to their distal tips. Inter radial membranes of dorsal fin darker, mainly in median region, with chromatophores distributed distally; in some specimens basal portion of dorsal fin lighter and chromatophores distributed only distally. Anal and caudal fins darker. Pelvic and pectoral fins lighter, with sparse chromatophores along fin rays.

rio Tapajós system.

Distribution. Known only from the type locality, rio Kaiapá drainage, a rio Teles Pires tributary of the rio Tapajós system.

Etymology. The name scutulatus , adjective, from Latin scutula, in allusion to the lozenge or diamond shaped marks formed by the dark lines bordering the scales of the dorsal portion of the body in the specimens.

Figures

Fig. 1. Hyphessobrycon scutulatus, holotype, MCP 33333, 34.73 mm SL, male, rio Kaiapá, rio Teles Pires drainage,