Skull morphology of the Brazilian shrew mouse Blarinomys breviceps (Akodontini; Sigmodontinae), with comparative notes on Akodontini rodents

Abstract Blarinomys breviceps is a shrew-like mouse, morphologically divergent from the remaining Akodontini (Cricetidae), and best known in the literature for its apparent fossorial adaptations. However, no detailed morphological description concerning its morphology and burrowing habits is available. Through a detailed osteological description and geometric morphometrics approach, we show the distinctiveness of the skull of Blarinomys when compared with other Akodontini. Its unique skull morphology shows some features that can be associated with its underground lifestyle. Many aspects of the peculiar morphology of Blarinomys may be attributed to selective pressures of the underground environment, and are convergent with the morphology of other fossorial rodents. However, in the Neotropics, Blarinomys represents one of the few instances of specialized fossorial habits among members of the Sigmodontinae.