[[ Astyanax ^ZBK ]]

Artificial key for identification of Astyanax ^ZBK species from the Río Bermejo Basin

1a. A well defined humeral spot, rounded or horizontally oval; without maxillary teeth ...... 2

1b. A vertically elongated or diffuse humeral spot; with 1-4 maxillary teeth.. ................. 3

2a. Scales in lateral line 38 to 49 (usually 44-47); usually 28-30 branched anal-fin rays... ........................................................................................................................ A. abramis

2b. Scales in lateral line 33 to 40 (usually 34-36); usually 23-27 branched anal-fin rays... .............................................................................................................. A. asuncionensis ^ZBK

3a. Pigmentation pattern with longitudinal stripes in zigzag between rows of scales; scales with circuli on posterior field ........................................................................ A. lineatus

3b. Pigmentation pattern not as above; scales without circuli on posterior field.. ............. 4

4a. Branched anal-fin rays 25 to 30 (usually 28-29); pectoral fins reaching pelvic fins, and pelvic fins reaching anal fin in mature males and females; 26-27 gill rakers on first branchial arch, outer premaxillary teeth tricuspidate ........................................ A. latens ^ZBK

4b. Branched anal-fin rays 17 to 24; pelvic fins usually not reaching anal fin in mature females; 19-21 gill rakers on first branchial arch; usually with pentacuspidate teeth on outer premaxillary row .................................................................................................. 5

5a. Maxilla meeting mouth commissure at a straight angle, reaching a vertical through anterior border of eye; snout nearly straight; premaxillary and dentary teeth conspicuously expanded; 35-39 scales in lateral line ..................................................... A. chico ^ZBK

5b. Maxilla meeting mouth commissure at an oblique angle, reaching the vertical through anterior border of pupil; snout markedly convex; premaxillary and dentary teeth not conspicuously expanded; 33-36 scales in lateral line .................................................. 6

6a. Pigmentation pattern reticulated, formed by finely dotted scales, especially in its posterior border; densely concentrated dark superficial chromatophores on third infraorbital, opercle, premaxilla, maxilla and dentary; hooks on all fins excepting pectorals in mature males, including 16-19 anterior anal-fin rays ........................... A. tumbayaensis ^ZBK

6b. Without reticulated pigmentation pattern; superficial chromatophores scattered only on tip of dentary, and practically absent on third infraorbital, opercle, premaxilla, and maxilla; hooks only on pelvic fins and first 12 anal-fin rays of mature males ......... A. endy