Revision of the subgenus Chonomantis (Anura : Mantellidae : Mantidactylus) from Madagascar, with description of two new species

摘要

A revision of Malagasy frogs of the subgenus Chonomantis (genus Mantidactylus ) led to the recognition of three additional species, increasing their number from four to seven. Mantidactylus melanopleura is resurrected from the synonymy of M. opiparis . Two new sibling species of M. albofrenatus , from mid-altitudes in central eastern Madagascar and from low altitude areas along the east coast, respectively, are described as M. zipperi and M. charlotteae . Although the neotype of Mantidactylus aerumnalis is not completely consistent with the original description of this species, we accept it as the valid name-bearing type and thus the re-definition of M. aerumnalis based on its designation. The six Chonomantis species for which call recordings were available (all but M. aerumnalis ) differed markedly in the temporal structure of their advertisement calls. Males of all seven species were easily distinguished by combination of relative tympanum size, relative toe length, amount of webbing, relative hindlimb length, and extension of frenal stripe. A key to all species and completely revised distribution maps are provided. Five of the seven species were found syntopically at a single locality in central eastern Madagascar, indicating that this region is the centre of diversity of the group. Chonomantis species diversity was highest at mid-altitude localities (500-1000 m elevation). The recognition of numerous sibling species in Chonomantis and other Malagasy anuran groups, which have been fairly well represented in scientific collections for decades, indicates that much revisionary taxonomic work is necessary before rigorous biogeographic analyses of the fauna are possible.