Simpsonichthys

Wilson J. E. M. Costa, 2007, Taxonomic revision of the seasonal South American killifish genus Simpsonichthys (Teleostei: Cyprinodontiformes: Aplocheiloidei: Rivulidae)., Zootaxa 1669, pp. 1-134 : 25

Subgenus Simpsonichthys Carvalho, 1959

Simpsonichthys Carvalho, 1959: 2 (type species: Simpsonichthys boitonei Carvalho; type by original designation).

Diagnosis

Distinguished from all other cynolebiatines by having pelvic fin and pelvic-fin girdle vestigial or absent and dark red bars on opercle in males.

Included species

Simpsonichthys cholopteryx Costa, Moreira & Lima, S. parallelus Costa, S. nigromaculatus Costa, S. punctulatus Costa & Brasil, S. boitonei de Carvalho, S. santanae (Shibata & Garavello), and S. zonatus (Costa & Brasil).

Distribution

Headwaters of rio Paraná, rio São Francisco, and rio Araguaia basins, central Brazil (Figs. 1 and 4).

Key to species of the subgenus Simpsonichthys

1a. Dwarf species, reaching about 25 mm SL; caudal fin with dark gray margin and subdistal blue line in males; dark gray distal stripe on dorsal and anal fins in males; pectoral fins hyaline in males ......................... 2

1b. Median sized species, reaching about 40 mm SL; caudal fin without dark margin and subdistal blue line in males; red distal stripe on dorsal and anal fins in males; pectoral fins red in males ................................ 4

2a(1a). 17-20 anal-fin rays in females; dorsal and anal fins orange in males; no dark bars on unpaired fins in males ........................................................ 3

2b(1a). 20-22 anal-fin rays in females; dorsal and anal fins light blue anteriorly, yellow posteriorly in males; dark red bars on unpaired fins in males ....................................... S. cholopteryx

3a(2a). No black spots on posterobasal portion of dorsal fin in males; no yellow dots on caudal fin in males; body depth in males 28.8-32.5 % SL ......................... S. parallelus

3b(2a). Two to four black spots on posterobasal portion of dorsal fin in males; yellow dots on caudal fin in males; body depth in males 33.5-36.0 % SL ............................................................ S. nigromaculatus

4a(1b). No longitudinal rows of light blue dots on flank in males; short filamentous ray on tip of dorsal fin in males, reaching basal portion of caudal fin ..................................................................................... 5

4b(1b). Longitudinal rows of light blue dots on flank in males; long filamentous ray on tip of dorsal fin in males, reaching the distal portion of caudal fin .............................................................. S. punctulatus

5a(4b). Pelvic fins vestigial; 20-23 anal-fin rays in males; black spots on dorsal-fin base in males.. .......... 6

5b(1b). Pelvic fins absent; 17-19 anal-fin rays in males; no black spot on dorsal-fin base in males.. ............. ....................................... S. boitonei

6a(5a). Dorsal-fin rays 19-21 in males, 14-17 in females; dorsal-fin origin anterior to anal-fin origin in males ..................................... S. santanae

6b(5a). Dorsal-fin rays 15-17 in males, 12-13 in females; dorsal-fin origin posterior to anal-fin origin in males ...................................................... S. zonatus