Systematics and biogeography of the genus Phalloptychus Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae)

the genus phalloptychus is revised. phalloptychus iheringii is removed from the synonym of p. januarius. three species are recognized: p. eigenmanni, p. januarius, and p. iheringii. phalloptychus eigenmanni can be distinguished from its congeners by the number of pelvic-fin rays in females, the number of predorsal scales, and the predorsal distance in females. phalloptychus iheringii and p. januarius can be distinguished by the number of epipleural ribs, number of gonopodial rays, and a significantly different number of vertical bars along body side in females. lectotypes are designated for girardinus iheringii and g. januarius. redescriptions and known distribution ranges are provided for each species as well as an identification key. derived features supportting the monophyly of the genus and infrageneric clades are presented and discussed. the biogeo-graphic implications of the geographic distribution of phalloptychus species are discussed.