The vast majority of Madagascar's 305 currently known frogs are endemic to the island. In fact an entire frog family (Mantellidae) is endemic to Madagascar. While the majority of the mantellid treefrogs belong to the genus Boophis, several other arboreal species are included in the genus Guibemantis and are in fact more closely related to terrestrial genera than to tree frog genera such as Boophis.
The new species was found in the Manombo Special Reserve in southeastern Madagascar by an old friend of mine. The species name is derived from the Greek root word “phon” meaning “sound” and the prefix “di-” meaning “two”. In phonetics, a diphone is an adjacent pair of phones. The advertisement call of Guibemantis diphonus is characterized by the distinct combination of two note types.
For the experts: We describe a new species of arboreal frog of the genus Guibemantis, subgenus Guibemantis, from low altitude rainforest in Manombo Special Reserve, south-eastern Madagascar. Previously published phylogenetic analyses of mitochondrial DNA sequences have placed Guibemantis diphonus sp. nov. sister to G. timidus. The new species is distinguished from G. timidus and all other species in the subgenus by a substantial genetic differentiation (≥ 4.4% uncorrected p-distance in the mitochondrial 16S rRNA gene), strongly divergent advertisement call, and some limited morphological differences. It is the smallest known species in the subgenus, with 34−36 mm snout-vent length in adult males. Its advertisement call is unique among other species in the subgenus in being composed of two distinctly different note types (only one note type in the other species).