45.

Anderson’s Red-backed Vole

Craseomys andersoni

French: Campagnol dAnderson / German: Anderson-Graurételmaus / Spanish: Topillo rojo de Anderson

Other common names: Japanese Red-backed Vole, Wakayama Red-backed Vole

Taxonomy. Evotomys (Craseomys) andersoni Thomas, 1905, near Morioka, Tsunagi, Iwate Prefecture, Honshu, Japan.

Craseomys anderson: is in the subgenus Phaulomys . It now includes niigate and imaizumu that had been treated as distinct species. Craseomys andersoni was also synonymized with C. smithii and was reported under different generic names: Evotomys, Aschizomys, Myodes, Clethrionomys, Eothenomys, and Phaulomys . Japanese authors still classify it as Eothenomys . Monotypic.

Distribution. Endemic to Japan (N & C Honshu and Kii Peninsula).

Descriptive notes. Head—body 79-132 mm, tail 40-79 mm; weight 11-60 g. Sexes of Anderson’s Red-backed Vole are similar in size, but there is great geographical variation in size. It is externally similar to the Gray Red-backed Vole ( C. rufocanus) but has longer tail, accounting for 48-68% of head-body length. There are four pairs of nipples, two pairs of pectoral and two pairs of inguinal nipples. Dorsal pelage is rusty brown or buff-brown and belly is yellowish gray-brown. Young individuals are grayer. Molars remain rootless throughout life.

Habitat. Shady and mesic places in rocky habitats and cultivated areas. Anderson’s Red-backed Vole is less resistant to water stress than the sympatric Smith’s Red-backed Vole ( C. smithii). These two species segregate habitat along an elevational gradient. In sympatric situations, Anderson’s Red-backed Vole occupies higher elevations (mainly above 400 m) but also occurs in lowlands where Smith’s Red-backed Vole is absent.

Food and Feeding. Anderson’s Red-backed Vole damages bark in young forest plantations.

Breeding. Reproductive biology of Anderson’s Red-backed Vole was studied in captivity. Youngest age of fertilization was estimated at 58 days. Ovulation occurred 10-15 hours after copulation, and gestation lasted 20-21 days. Litters of captive voles had 2-6 young (mean 3-9) and did not differ between primiparous and multiparous females. Males attained sexual maturity at 60 days old and at weights of 30 g or more. Free-living females from the Kii Peninsula have an average of 3-4 embryos. Sex ratio is balanced in young. Maximum lifespan in captivity was 1098 days for males and 1243 days for females.

Activity patterns. Anderson’s Red-backed Vole is nocturnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as Myodes andersont). Distribution of Anderson’s Red-backed Vole is fragmented and encompasses ¢.104,000 km?.

Bibliography. Iwasa (2015a), Kitahara (1993, 1995).