Simpsonichthys de Carvalho

Wilson J. E. M. Costa, 2006, Three new species of seasonal killifishes of the Simpsonichthys antenori species group (Teleostei: Cyprinodontiformes: Rivulidae) from the rio São Francisco basin, Brazil., Zootaxa 1306, pp. 25-39 : 37-38

[[ Genus Simpsonichthys de Carvalho ]]

Discussion

The present study reveals a great diversity of species of the Simpsonichthys antenori group in the upper sections of eastern tributaries of the middle rio São Francisco in serra do Espinhaço, including rio Verde Grande, rio Carnaiba de Dentro, and rio Paramirim. The species inhabiting this area, S. janaubensis , S. mediopapillatus , S. ghisolfii , and S. macaubensis , were not found in other places during recent intensive field studies in the region, suggesting that they are geographically restricted to short sections of the river drainages. In the lower portions of the rio Verde Grande and rio Carnaiba de Dentro, they are replaced by S. flagellatus , a species widespread throughout the rio São Francisco basin (Fig. 3). This suggests that species endemic to the upper sections are effectively isolated from congeners inhabiting the lower sections.

The species endemic to upper tributaries of the rio São Francisco draining the serra do Espinhaço do not constitute a monophyletic assemblage. Among them, S. janaubensis is a member of a clade defined by Costa (2006), including S. flavicaudatus and S. flagellatus , which are diagnosed by the derived color patterns of the anal fin in males: anterior portion pink, posterior portion yellow; bright blue or white dots on posterior part of fin, but not on anterior part; and presence of a light gray distal stripe. Simpsonichthys janaubensis is therefore considered more closely related to S. flavicaudatus and S. flagellatus than to other species from the Serra do Espinhaço (i. e., S. mediopapillatus , S. ghisolfii , and S. macaubensis ). On the other hand, S. mediopapillatus and S. ghisolfii are sister species, since both share an apomorphic long urogenital papilla in males, a condition not found elsewhere among species of Hypsolebias (Costa, 2006).

Key to species of the S. antenori group

1a. Dorsal and anal-fin filaments reaching between central and posterior portion of caudal fin, or surpassing it in males; unpaired fins pink, yellow or orange in males .................................................................................................................................2

1b. Dorsal and anal-fin filaments short, reaching caudal-fin base; unpaired fins dark bluish gray in males................................................................................. S. antenori

2a(1a). Filamentous rays of dorsal and anal fins of moderate length in males, tip of each fin reaching posterior portion of caudal fin............................................................3

2b(1a). Filamentous rays of dorsal and anal fins rather long in males, tip of each fin extending beyond posterior margin of caudal fin...................................................5

3a(2a). Urogenital papilla long in males, notably conspicuous in lateral view (Fig. 6C)............................ 4

3b(2a). Urogenital papilla short in males, almost imperceptible in lateral view................... .......................................................................................................... S. macaubensis

4a(3a). No contact organs on flank in males; a median neuromast on posterior rostral series (Fig. 6B)........................................................................... S. mediopapillatus

4b(3a). Contact organs on anteroventral portion of flank in males; no median neuromast on posterior rostral series......................................................................... S. ghisolfii

5a(2b). Six pelvic-fin rays; flanks with gray bars and few or no light dots in males; anal fin pink anteriorly and yellow posteriorly, with gray distal stripe in males................6

5b(2b). Seven pelvic-fin rays; flanks of males without bars or sometimes hardly visible only in preserved specimens, and with numerous light dots; anal fin yellow, with orange subdistal stripe and black distal stripe in males.............................. S. igneus

6a(5a). Pectoral-fin contact organs pronounced in males; dorsal profile of head conspicuously concave; anterobasal portion of dorsal fin with short light stripes alternating with dark gray to black areas..................................................................................7

6b(5a). Pectoral-fin contact organs minute in males; dorsal profile of head nearly straight; anterobasal portion of dorsal fin with small light spots, sometimes slightly elongated ................................................................................................. S. flavicaudatus

7a(6a). Elongated light blue spots restricted to anterior portion of dorsal-fin base in males; anal-fin base in males 39.0-45.2 % SL; body depth in combined sexes 37.0-42.7%; caudal-peduncle depth in combined sexes 13.4-16.6%............................. S. flagellatus

7b(6a). Elongated light blue spots along entire dorsal-fin base in males; anal-fin base in males 34.4-38.4 % SL; body depth in combined sexes 30.7-38.4%; caudal-peduncle depth in combined sexes 11.7-14.3% .......................................... S. janaubensis