Middle-American poeciliid fishes of the genera Carlhubbsia and Phallichthys with descriptions of two new species

" The fishes of the family Poeciliidae (Order Cyprinodontiformes, also known as Cyprinodontida, Cyprinodontes and Microcyprini) are all from the New World and most of the species bear living young. They abound in the fresh and brackish waters of Mexico, the West Indies and northern and eastern South America, but attain their maximum diversity in Central America (Rosen & Gordon, 1953: 1-6). In Middle America three nominal species classified in two genera, Carlhubbsia (formerly Allophallus) and Phallichthys, have heretofore been regarded as closely related. Their many superficial resemblances include the asymmetric twisting or folding, either sinistrally or dextrally, of the external genitalium (gonopodium) of the adult male. This modification is shared by several other genera (Poeciliopsis, Aulophallus, Phalloptychus and Xenophallus). On the basis of this one feature, all of them have been grouped as the subfamily Poeciliopsinae (Hubbs, 1926; 1936).

We now find evidence, however, that asymmetry of the gonopodium is not in itself an adequate criterion of the implied phylogenetic relationships of the fishes in the Poeciliopsinae. As in other poeciliids, it is the fine details of the gonopodia and characters in the gonopodial suspensoria that provide the most useful criteria in determining relationship. On the basis of new data, Carlhubbsia shows affinities to Quintana and Girardinus (including Toxus, Glaridichthys, Allodontium and Dactylophallus); these are endemic Cuban fishes with symmetrical gonopodia. Phallichthys is closely allied to Poeciliopsis (including Poecilistes) and Aulophallus, but the remaining genera previously associated with them in the Poeciliopsinae are not intimately related. For these reasons the dissolution of the Poeciliopsinae is now recommended "