A revision of Mantidactylus microtis and M. microtympanum, and a comparison with other large Madagascan stream frogs (Anura: Mantellidae: Mantellinae)

Abstract

We revise two stream frogs, Mantidactylus microtis and M. microtympanum, providing data on its known distribution and life history traits, based upon observations in nature. For M. microtis we show for the first time photographs of the live individuals, while for M. microtympanum we also describe its putative tadpoles. The transfer of microtis from Boophis to Mantidactylus is formally justified by morphological and ecological traits, e.g., the lack of nuptial pads, the torrenticolous life style and the low number of eggs. Mantidactylus microtis shares some characters with M. microtympanum: distribution (both live in south-eastern Madagascar), natural history (both are stream frogs), morphology (wide digital expansions, lack of femoral glands, presence of a mostly unforked omosternum, cryptic dorsal colouration, small tympanum, and presence of a derived cloacal structure). Mantidactylus microtympanum differs from the species of the subgenus Mantidactylus (M. grandidieri and M. guttulatus), to which it was so far ascribed, for the lack (vs. presence) of femoral glands, and presence of expanded (vs. moderately expanded) fingertips. Whether M. microtis and M. microtympanum are phylogenetically related, or their overall similarity is due to convergence, is discussed.