A new species of Mantidactylus from the east coast of Madagascar and its molecular phylogenetic relationships within the subgenus Guibemantis

We describe a new species of arboreal frog of the genus Mantidactylus from low altitude sites on the eastern coast of Madagascar. Mantidactylus timidus sp. n. has hitherto been considered as Mantidactylus tornieri, but some of the characters that distinguish it from typical populations of this species from mid-altitude localities had already been detected. The new species mainly differs from M. tornieri and all related species in the subgenus Guibemantis by a shorter relative hand length. Furthermore, it has shorter hind limbs, a smaller tympanum diameter and – at least in some populations – green egg pigmentation (as opposed to brown or white). Vocalizations of M. timidus were irregular and unstructured blasts and moans but the available recordings may not represent the real advertisement calls. A molecular phylogeny based on analysis of 539 nucleotides of the mitochondrial 16S rRNA gene placed the new species sister to a clade containing M. tornieri, M. depressiceps and M. kathrinae. Genetic differentiation from these related species was large, with uncorrected pairwise divergences of more than 8 % in all cases. We discuss the recently increasing use of mitochondrial genetic markers to draw taxonomic conclusions and suggest that mitochondrial differentiation should not be used as an exclusive character to describe new amphibian taxa. Instead, phylogenetic placement of populations and morphological, ecological and behavioural arguments need to be carefully evaluated in each case to understand whether a population merits the status of a separate species