Simpsonichthys (Xenurolebias),

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: 7

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Simpsonichthys (Xenurolebias)


Subgenus Xenurolebias  Costa, 2006

Xenurolebias  Costa, 2006a: 16 (type species: Simpsonichthys myersi  (de Carvalho); type by original designation).


Distinguished from all other rivulids by the following unambiguous synapomorphies (Costa, 2006a): presence of filamentous rays on the posterior margin of anal fin in females (vs. absent in females), caudal fin lanceolate and asymmetrical due to expansion of ventral portion of fin in males (vs. caudal fin rounded or subtruncate; dorsal and ventral portion symmetrical), and a unique color pattern consisting of a bar on posterior portion of caudal peduncle, posteriorly extending over dorsal and ventral margins of caudal fin in males (vs. never a similar color pattern).

Included species

Only the type species, Simpsonichthys myersi  (Carvalho).


Rivers basins of eastern Brazilian coastal plains between rio Jucuruçu, southern Estado da Bahia, and rio Doce, Estado do Espírito Santo (Fig. 1).