179.

Transcaspian Vole

Microtus transcaspicus

French: Campagnol transcaspien / German: Transkaspien-Feldmaus / Spanish: Topillo del Caspio

Other common names: Middle East Vole

Taxonomy. Microtus transcaspicus Satunin, 1905, near Ashabad, Tschuli Gorge, Kopet Dag Mountains, Turkmenistan.

Microtus transcaspicus is in subgenus Microtus. In the past, transcaspicus included laeus and kermanensis . Microtus transcaspicus has a unique karyotype of 52 chromosomes. Phylogenetic analyses retrieved sister position of M. transcaspicus against a clade of M. arvalis, M. obscurus, and M. mystacinus . Monotypic.

Distribution. W & C Kopet Dag on the border between Turkmenistan and Iran, Binalud Mts and nearby ridges in NE Iran, and E Afghanistan; it may also occur in SE Turkmenistan, but recorded specimen could be misslabeled.

Descriptive notes. Head-body 97-135 mm (males) and 100-140 mm (females), tail 41-55 mm (males) and 38-52 mm (females); weight 42:3-77 g (males) and 36-80 g (females). Males are on average slightly heavier (54-5 g) than females (51 g). The Transcaspian Vole is large and heavy, with tail averaging 45% of head-body length. There are six plantar pads. Females have eight nipples, two pairs each of pectoral and inguinal. Back is buffy brown to grayish brown, belly is gray, and flanks are usually yellowish. Skull is very similar to that of the Kerman Vole (M. kermanensis). Upperincisors are orthodont. Molar pattern is more similar to that of the East Eurpoean Vole ( M. mystacinus) than the Kerman Vole.

Habitat. Humid meadows, frequently river valleys and flooded lowlands, and irrigated land, mainly at elevations of 500-1500 m in Kopet Dag and 2500-2800 m in Afghanistan.

Food and Feeding. Little is known, but the Transcaspian Vole can damage orchards.

Breeding. Breeding season starts in April and is confined to spring. Adult females have 2-3 litters/season, and young females have 1-2 litters in their first year. Numbers of embryos are 3-9/female (mean 6). Litters in the laboratory have 1-6 young (mean 3-4). Captive females are sexually mature at 1-5 months old. Adult size is reached at 2-5-3 months old.

Activity patterns. Transcaspian Voles are active day and night, with peaks in morning and evening. They excavate simple and shallow burrows descending 12-15 cm. Diameters of holes are 4.3-5.2 cm. Burrow system has 50-105 cm of tunnels, nest chamber, and 2-6 exits. Nest chamber is spherical (7-10 cm in diameter) and lined with soft grass. On the ground’s surface, entrances are connected by a network of pathways through vegetation.

Movements, Home range and Social organization. During dry periods, Transcaspian Voles move to humid spots with lush vegetation. Burrow systems cover 3-7 m? but can merge to cover 3500 m*. Small colonies are widely scattered and presumably quite isolated.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Overall distribution of the Transcaspian Vole is 10,000-15,000 km? Further aridization may negatively impact Transcaspian Voles.

Bibliography. Golenishchev (2016b), Mahmoudi et al. (2017), Meyer et al. (1996), Sapargel'dyev (2005).