164.

Thomas's Pine Vole

Microtus thomasi

French: Campagnol de Thomas / German: Balkan-Kleinwihlmaus / Spanish: Topillo de Thomas

Taxonomy. Microtus (Pitymys) thomas: Barrett-Hamilton, 1903, “Vranici [near Podgorica], Montenegro, 100 m. ”

Microtus thomast is in subgenus Terricola and thomas: species group. It consists of at least seven different chromosomal races, with diploid numbers between 38 and 44 that cluster into two deeply divergent phylogenetic lineages. The two lineages show considerable degree of reproductive isolation and possibly represent distinct species, thomasi and atticus (henceforth classified as subspecies). It was in the past classified in the genus Pitymys . Two subspecies recognized.

Subspecies and Distribution.

M.t.thomas:Barrett-Hamilton,1903—majorityofspecies’rangeinSBosniaandHerzegovina,Montenegro,Albania,andGreeceasSasPeloponnese(exceptEuboeaIandAttica).

M. t. atticus G. S. Miller, 1910 — Euboea I and Attica region (SE Greece).

Descriptive notes. Head-body 71-119 mm, tail 12-30 mm; weight 20-5-43-5 g. Thomas’s Pine Vole is, on average, larger in the north (mean head-body length 102-4 mm) than in the south (88-2 mm). It is relatively large and robust, with large and rounded head. Tail is short, 16-23% of head-body length. Females have one pectoral and two inguinal pairs of nipples (six nipples in total). Pelage is deep reddish brown on back, buff along flanks, and dark gray on belly. Head is darker than back. Skull is robust and deep, with expanded zygomatic arches, constricted interorbital region, and convex profile. Angular process of mandible is prominent and turned outwardly. Incisors are proodont, and they protrude from mouth because they are not concealed by lips. M® has very short posterior cup, and M, is longer than in other pine voles.

Habitat. Dry to moderately mesic meadows, light woodland, arable land, and orchards from sea level to elevations of ¢.2000 m. Soil must be deep enough to allow digging and well drained.

Food and Feeding. Thomas's Pine Vole eats various plant parts, and food is cached. Caches contain rhizomes, roots, bulbs, tubers, green leaves and stalks (e.g. couch grass Cynodon dactylon, Poaceae, and clover, Trifolium, Fabaceae), seeds, and fruits (e.g. olives).

Breeding. Female Thomas's Pine Voles have 2-8 embryos (mean 4-6).

Activity patterns. Daily activity is polyphasic. Thomas's Pine Vole is fossorial and only occasionally active aboveground. No runways, which are common among arvicolines, are chewed through vegetation to connect entrances. Underground burrow systems are excavated by rapidly moving front feet, aided by incisors. Tunnels (diameters 3.5-4 cm) frequently follow roots or stones. Lengths are 3-25 m/ system (mean 13-5 m). Excavated soil is pushed on the ground’s surface by head and hindfeet and deposited in heaps 5-25 cm in diameter and 3-15 cm high. Digging is triggered by rains that soften soil. Older the system, the more complex it is because new tunnels are added. Tunnels are either close to the ground’s surface or descend up to 60 cm. Individuals easily move through tunnels either forward or backward and can turn to change direction. Nest and storage chambers are attached to tunnels. Nests woven of dry plant material are frequently under large roots or stones that give extra protection; they are 10-40 cm below the ground’s surface and usually have three exits. Nests are kept tidy, with very few fecal droppings and no urine inside. In captivity, males and females participate in nest construction. Lactating females and juveniles are most active. Spherical or cylindrical caches are located less than 2 m from the nest. Thomas’s Pine Voles maintain and repair tunnels, particularly those near nesting chambers. During hot and dry season, they use burrows in subsoil and avoid dry topsoil. Entrances are occasionally left open, presumably for ventilation.

Movements, Home range and Social organization. Thomas’s Pine Voles may share a communal burrow system. Captive individuals frequently use same nests.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as Microtus thomast).

Bibliography. Giagia-Athanasopoulou & Stamatopoulos (1997), Mitsainas et al. (2009), Niethammer (1982h), Rovatsos & Giagia-Athanasopoulou (2012), Shenbrot & Krasnov (2005), Stamatopoulos & Ondrias (1986), Thanou et al. (2012).