A new species of the endemic Tarsomys clade (Muridae, Rodentia) from eastern Mindanao Island, Philippines

Abstract

Abstract Based on molecular and morphological evidence, we describe a new species of murine rodent from Mt. Kampalili in easternmost Mindanao Island, Philippines. It is the third known species of Tarsomys, a genus endemic to Mindanao. The new species differs from congeners (T. apoensis and T. echinatus) in having smaller body size, shorter tail, smaller hind feet, soft and dense pelage of darker color, smaller skull with a broader zygomatic plate, shorter incisive foramina, and longer auditory bullae. The new species belongs to the “Tarsomys clade” of tribe Rattini that has diversified principally on Mindanao where, in addition to the 3 species of Tarsomys, it is represented by 2 species of Limnomys and 1 species of Baletemys. The Tarsomys clade also includes the Rattus everetti complex which is widespread throughout the oceanic portion of the Philippines and likely consists of at least 4 species. Molecular phylogenetic analysis strongly supports a sister relationship between this new species and T. apoensis, which diverged approximately 1.0 to 1.75 Ma. The phylogenetic position, morphological distinctness, and relatively ancient persistence of this species support within-island diversification as the most substantial contributor to existing species richness of small mammals in the Philippines.