Pachypanchax Myers

Paul V. Loiselle, 2006, A review of the Malagasy Pachypanchax (Teleostei: Cyprinodontiformes, Aplocheilidae), with descriptions of four new species., Zootaxa 1366, pp. 1-44 : 2-3

[[ Genus Pachypanchax Myers ]]

Introduction

Myers (1933) established the genus Pachypanchax for Haplochilus playfairii Guenther, 1866 , a robust killifish endemic to the granitic Seychelles (Playfair and Günther, 1866). He included two Malagasy species, Poecilia omalonota Dumeril, 1861 and Panchax sakaramyi Holly, 1928 in his new genus. This attribution appears to have been made on biogeographic grounds, as Myers clearly indicated that he had not examined specimens of either Malagasy species. Scheel (1968) refined Myer’s definition of the genus with the addition of two additional diagnostic characters. However, the material of P. omalonota available to Scheel consisted of aquarium-reared specimens descended from fish collected from the lower reaches of the westward-flowing Betsiboka River, on the mainland of Madagascar (Arnoult, 1955), whereas the type material of P. omalonotus actually came from the island of Nosy Be, off northwestern Madagascar. Subsequent collecting has demonstrated these two taxa differ sufficiently in coloration and morphology to warrant recognition as separate species. Parenti (1981) subsequently redefined the genus, placing particular emphasis upon several skeletal apomorphies. However, Parenti neither examined topotypical material of P. omalonotus nor specimens of the other two nominal Malagasy species, P. sakaramyi and P. nuchimaculatus (Guichenot, 1866) . Her inclusion of the Malagasy species within the genus was thus tentative.

Fieldwork in Madagascar undertaken since 1993 has resulted in the collection of larger series of both P. omalonotus and P. sakaramyi , and in the discovery of additional aplocheilid taxa that cannot be referred to previously published nomina. In light of these discoveries, it is appropriate to reexamine Parenti’s definition of the genus Pachypanchax , redescribe P. omalonotus and P. sakaramyi , and describe four of these new taxa. Three more recently discovered Malagasy species remain to be described.