Notes on Forefoot Characteristics of the Ryukyu Long-Furred Rat, Diplothrix legata, for Its Arboreal Lifestyle

A unique adaptation for arboreal life is identified in the Ryukyu long-furred rat (Diplothrix legata), native to Amami-Oshima, Tokunoshima, and Okinawa Island. The study reveals that the species possesses a nail on its pollex—a rare feature among murids—and a linear palmar groove between interdigital pads, which enables it to grip thin branches effectively. This groove allows the rat's fingers (excluding the pollex) to securely grasp twigs, suggesting an evolutionary specialization for tree-dwelling behavior. Additionally, geographical variation in unguis size was observed, with larger claws noted on Okinawa Island compared to Amami-Oshima Island. The research combines morphological analysis with functional testing to elucidate these adaptations.

Iwasa, M. A., Kaneko, Y., & Kawada, S.-i. (2020). Notes on Forefoot Characteristics of the Ryukyu Long-Furred Rat, Diplothrix legata, for Its Arboreal Lifestyle. Mammal Study, 45(3), 253. https://doi.org/10.3106/ms2019-0076