Astyanax erythropterus

description

Color in alcohol. Background light yellow, dorsal region of body and head darker (Figs. 3 - 4). Dark narrow stripe extending along dorsal midline from supraoccipital spine tip to base of dorsalmost caudal-fin ray. Dark lateral band wide beginning at upper opercular posterior margin, ending with a triangular spot on caudal peduncle. Adults usually with faint dark vertically elongated humeral spot situated between 4 th to 7 th scales of longitudinal series above lateral line, upper half of humeral spot wider than lower half. Humeral spot always present in juveniles, absent in some adults. Scales of upper half of body with scattered dark chromatophores. Small chromatophores present on premaxilla and lower jaw regions. Gray chromatophores aligned on dorsal margin of lower jaw region. Dorsal and adipose fins pale gray; dorsal fin with scattered black chromatophores on its surface, adipose fin with black cromatophores more concentrated on its margin. Caudal fin pale gray with small black chromatophores on distal margin. Anal fin pale yellow. Pectoral fin pale gray with scattered chromatophores on first five rays. Pelvic fins pale yellow. Color in life. Adults (Fig. 2): background silvery

Redescription of Astyanax erythropterus (Holmberg, 1891) (Teleostei: Characiformes: Characidae) from La Plata basin in Argentina

description

Description. Body deep, with maximum body depth located at dorsal-fin origin (Figs. 1 - 4). Dorsal profile of head slightly convex from snout tip to vertical through anterior margin of eyes, concave from this last point to supraoccipital spine in adults, slightly convex in juveniles. Dorsal profile of body markedly convex from tip of supraoccipital spine to base of first dorsal-fin ray in adults, slightly convex in juveniles. Dorsal profile slanting ventrally from dorsal-fin origin to caudal peduncle; slightly concave on caudal peduncle. Ventral profile of body convex from tip of lower jaw to anal-fin origin, posterodorsally slanted along analfin base, slightly concave on caudal peduncle. Dorsal-fin origin almost equidistant from snout tip and caudal-fin base. Pelvic-fin origin anterior to vertical through dorsal fin-origin. Anal-fin origin slightly posterior to vertical through base of last dorsal-fin ray. Origin of adipose fin at vertical through base of 25 - 27 branched anal-fin rays. Tip of longest pectoral-fin rays always extending slightly beyond pelvic-fin origin. Tip of longest pelvic-fin rays not reaching anal-fin origin in adult specimens, reaching or extending slightly b

Redescription of Astyanax erythropterus (Holmberg, 1891) (Teleostei: Characiformes: Characidae) from La Plata basin in Argentina

diagnosis

Diagnosis. Astyanax erythropterus is distinguished from all species of the genus, except A. pelegrini, by the presence of a long anal fin bearing 38 to 42 branched rays (vs. 34), a large number of perforated scales on the lateral series (49 - 54 vs. 48), and the juveniles (18.0 - 29.9 mm SL; Fig. 1) with the dorsal, anal and caudal fins vermilion red. Astyanax erythropterus differs from A. pelegrini by the number of transverse scales below the lateral line (8 - 10 vs. 7 - 8). Astyanax erythropterus can be distinguished from the six sympatric species by the great number of branched anal-fin rays 38 - 42 (vs. 30 - 34 in A. abramis, 30 - 32 in A. asuncionensis, 29 - 33 in A. correntinus; 22 - 24 in A. eigenmanniorum; 23 - 26 in A. rutilus; and 25 - 30 in A. stenohalinus).

Redescription of Astyanax erythropterus (Holmberg, 1891) (Teleostei: Characiformes: Characidae) from La Plata basin in Argentina

distribution

Distribution. Astyanax erythopterus was found in the middle and lower río Paraná and Río de la Plata basin (Fig. 7).

Redescription of Astyanax erythropterus (Holmberg, 1891) (Teleostei: Characiformes: Characidae) from La Plata basin in Argentina