Simpsonichthys (Ophthalmolebias)

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 : 12-14

Subgenus Ophthalmolebias Costa, 2006

Ophthalmolebias Costa, 2006a: 16 (type species: Simpsonichthys constanciae (Myers); type by original designation).

Diagnosis

Distinguished from all other cynolebiatins by the following unambiguous synapomorphies (Costa, 2006a): a medial crest with a prominent ventral expansion on the autopalatine (vs. without ventral expansion when crest is present), eyes positioned laterally on head (vs. dorsolaterally), anterior and posterior sections of the supraorbital series of neuromasts separated by an interspace (vs. continuous), and anal fin pink in females (vs. hyaline). According to Fava & Toledo-Piza (2007), Ophthalmolebias may also be diagnosed by the presence of palm-like projections on the egg chorion surface, present in all species of the subgenus except S. bokermanni , which exhibits the unique presence of 1-3 filaments at the distal tip of the chorion projection.

Included species

Simpsonichthys constanciae (Myers), S. bokermanni (de Carvalho & da Cruz), S. perpendicularis Costa, Nielsen & De Luca, S. rosaceus Costa, Nielsen & De Luca, and S. suzarti Costa.

Distribution

All species of Ophthalmolebias except S. constanciae are endemic to the area of eastern Brazil between rio Cachoeira and rio Pardo basins, Estado da Bahia, in a rain forest region. Simpsonichthys constanciae is endemic to the plains adjacent to the lower rio São João, Estado do Rio de Janeiro, a semi-arid coastal zone.

No species of Ophthalmolebias is known to occur in the broad area between the rio Pardo and rio São João basins (Fig. 4).

Key to species of the subgenus Ophthalmolebias

1a. No black spots on flank of males; dorsal and anal fins with short filamentous rays in males, tip not surpassing vertical through posterior margin of caudal fin; anal fin short, nearly rectangular; some dorsal and anal-fin rays branched; males with contact organs on flank scales and inner surface of upper pectoral-fin rays ......................................................................................................................... 2

1b. Four longitudinal rows of rounded black spots on male flank; dorsal and anal fins with long filamentous rays in males, tip posteriorly surpassing posterior margin of caudal fin; anal fin long, nearly triangular; all dorsal and anal-fin rays unbranched; contact organs of flank and pectoral fin absent ....... ....................................................................................................................................... S. constanciae

2a(1a). Anal-fin extremity rounded in males ................................................................................................... 3

2b(1a). Anal-fin extremity pointed in males ................................................................................................... 4

3a(2a). 22-23 caudal-fin rays; 3 + 11 gill-rakers on first branchial arch; 24-25 scales in longitudinal series; reddish brown bars alternating with bright greenish blue bars on whole male flank; oblique brown bars on male anal fin............................................................................................................... S. suzarti

3b(2a). 25-27 caudal-fin rays; 4 + 14 gill-rakers on first branchial arch; 26-28 scales in longitudinal series; dark purplish brown bars on anterior part of flank, three horizontal purplish brown stripes on posterior part of flank in males; no bars on anal fin......................................................... S. perpendicularis

4a(2b). Dorsal-fin origin on vertical through base of anal-fin rays 6-7; no bright dots on unpaired fins in males.................................................................................................................................... S. rosaceus

4b(2b). Dorsal-fin origin on vertical through base of anal-fin ray 8; white dots on dorsal fin and dorsal half of caudal fin in males..................................................................................................... S. bokermanni