Revision of the Subgenus Ochthomantis Frogs from Madagascar (Amphibia: Mantellidae) with the Description of Four Species and Resurrection of Mantidactylus catalai and M. poissoni †

SIMPLE SUMMARY: The genus Mantidactylus spp. is one of the exceptionally diverse amphibian clades from Madagascar. Currently, 57 species in 6 subgenera are recognized. One subgenus, Ochthomantis, is the focus of the present study. Here, we revise this taxonomic group to recognize the presence of cryptic species through an assessment of morphological and, where available, molecular (16S mitochondrial gene) variation of 637 sexed adult specimens. Our results show that Ochthomantis contains eleven species, including the resurrected Mantidactylus catalai and M. poissoni, and four newly described species. We cannot confirm that M. majori should be considered as part of the subgenus Ochthomantis, so we do not include it in our descriptions. Following our taxonomic revision, we also present a practical simple key to identify all of the species belonging to this subgenus. ABSTRACT: The subgenus Ochthomantis is an obligate forest and stream-dwelling group of mantellid frogs, endemic to Madagascar, with six species currently recognized. However, this group suffers from ongoing taxonomic confusion due to low numbers of examined specimens, and failure to consider morphological variation from development and sexual dimorphism. Here, we examined the morphology of 637 sexed adult specimens collected by us in the field and from other museum collections. We also sequenced a DNA fragment of the 16S mtDNA gene for each lineage to determine congruence between morphological and molecular data sets and to help delimit species. Our results demonstrate that the subgenus Ochthomantis includes eleven valid species: five already recognized, M. catalai and M. poissoni that we resurrect from synonymy, and four new species which we describe for the first time here. In some analyses, Mantidactylus majori groups with other Mantidactylus subgenera, so we do not consider it a member of the subgenus Ochthomantis in this study. All species have restricted distributions and elevational ranges in the humid forests of Madagascar. This study demonstrates the utility of assessing cryptic species using both diagnostic morphological characters and molecular data. The discovery of this new cryptic biodiversity, and the taxonomic revision herein, will likely require conservation activities for those species with the most restricted distributions.