Resolving a taxonomic and nomenclatural puzzle in mantellid frogs: synonymization of with , and description of sp. nov. from the Isalo Massif, western Madagascar.

The genus belongs to the species-rich family Mantellidae and is currently divided in six subgenera. Among these is the subgenus Phylacomantis, which currently includes four described species: , , , and . The latter three species are distributed in western Madagascar, and two of them ( and ) occur in the Isalo Massif. Based on the analysis of molecular data (a fragment of the 16S rRNA gene), morphological inspection of museum specimens, and photographic comparisons, is synonymised with and the second lineage of Isalo is described as This medium-sized frog species (adult snout-vent length 35-44 mm) is assigned to this subgenus according to genetic and morphological similarities to the other known species of . is known only from the Isalo Massif, while new records for extend its range to ca. 200 km off its currently known distribution. These two taxa seem to occur in syntopy in at least one locality in Isalo, and the easiest way to distinguish them is the inspection of the ventral colouration, dark in and dirty white in .