Calomys tocantinsi Bonvicino

Rocha, Rita G., Ferreira, Eduardo, Costa, Barbara M. A., Martins, Iracy C. M., Leite, Yuri L. R., Costa, Leonora P. & Fonseca, Carlos, 2011, Small mammals of the mid-Araguaia River in central Brazil, with the description of a new species of climbing rat, Zootaxa 2789, pp. 1-34 : 13-14

Calomys tocantinsi Bonvicino , Lima and Almeida

Identification. A small-sized species with tail length shorter than head and body length. Dorsal pelage is grayish brown and body sides are lighter than the dorsum; ventral pelage is whitish gray. It has characteristic white fur patches posterior to the base of the ears. The bicolored tail is ventrally covered by light hairs and dorsally covered by dark hairs. Front and hind feet are white and the claws are covered by long ungual hairs.

Craniodental characters of our specimens ( Fig. 4 ) closely agree with the description of this species by Bonvicino et al. (2003). The rostrum is narrow and short, and incisors are opisthodont, the interorbital region converges anteriorly and has weakly developed supraorbital ridges. Incisive foramina are parallel-sided and long, reaching the procone of M1. The anterior edge of mesopterygoid fossa reaches the posterior plan of M3. The alisphenoid strut is absent. The M2 is similar to M1, but lacks the procingulum and M3 is clearly smaller than M2.

Measurements (n = 16): HB = 82–115, T = 71–80, HF = 19–23, E = 18–20, W = 20–56.

Distribution. Calomys tocantinsi is endemic to the Cerrado of central Brazil ( Bonvicino et al. 2003) and previously known from just six localities in the states of Tocantins and Mato Grosso ( Bonvicino et al. 2010).

Natural history. Twenty-three individuals (17 adults and six juveniles) of C. tocantinsi were captured on both banks of the Araguaia River. These captures were in pitfalls (n = 10) and Sherman traps (n = 13) placed mainly in grasslands. An additional skull was found inside a pitfall that was found open during a non-trapping period. Nine out of 12 females captured in October and November 2008 were reproductively active: three were pregnant, with five, seven and 10 embryos each, five had open vagina, and one was lactating.

Vouchers (n = 16: 7ɗ 8Ψ 1 skull): UFES 1289–1303, 1423.

Figures

FIGURE 4. Dorsal, ventral and lateral views of skull and mandible of Calomys tocantinsi (male, UFES 1285).