Transandinomys Talamancae

Transandinomys talamancae is a rodent in the genus Transandinomys that occurs from Costa Rica to southwestern Ecuador and northern Venezuela. Its habitat consists of lowland forests up to 1525 m (5000 ft) above sea level. With a body mass of 38 to 74 g (1.3 to 2.6 oz), it is a medium-sized rice rat. The fur is soft and is reddish to brownish on the upperparts and white to buff on the underparts. The tail is dark brown above and lighter below and the ears and feet are long. The vibrissae (whiskers) are very long. In the skull, the rostrum (front part) is long and the braincase is low. The number of chromosomes varies from 34 to 54.

The species was first described in 1891 by Joel Asaph Allen and thereafter a variety of names, now considered synonyms, were applied to local populations. It was lumped into a widespread species "Oryzomys capito" (now Hylaeamys megacephalus) from the 1960s till the 1980s and the current allocation of synonyms dates only from 1998. It was placed in the genus Oryzomys until 2006, as Oryzomys talamancae, but is not closely related to the type species of that genus and was therefore moved to a separate genus Transandinomys in 2006. It shares this genus with Transandinomys bolivaris, which has even longer vibrissae; the two overlap broadly in distribution and are morphologically similar.

Active during the night, Transandinomys talamancae lives on the ground and eats plants and insects. Males move more and have larger home ranges than females. It breeds throughout the year, but few individuals survive for more than a year. After a gestation period of about 28 days, two to five young are born, which reach sexual maturity within two months. A variety of parasites occur on this species. Widespread and common, it is of no conservation concern.