312.

Oaxacan Big-toothed Deermouse

Megadontomys cryophilus

French: Péromyscus de Musser / German: Oaxaca-Grol 3zahn-Hirschmaus / Spanish: Raton ciervo de dientes grandes de Oaxaca

Other common names: Oaxaca Giant Deermouse, Oaxacan Giant Deermouse

Taxonomy. Peromyscus thomasi cryophilus Musser, 1964, south slope Cerro Pelon, 9200 ft (= 2804 m), 13 mi (= 24 km) NE [lano de las Flores, Distrito de Ixtlan, Oaxaca, Mexico.

Megadontomys cryophilus was recognized as a subspecies of M. thomasi but elevated to species status. The validity of the genus Megadontomysis still much debated. Monotypic.

Distribution. Restricted to the type locality and surrounding regions in the highelevations of Sierra Juarez, NC Oaxaca .

Descriptive notes. Head—body c.145-146 mm,tail 155-185 mm, ear 21-22 mm, hindfoot 31-33 mm; weight 73-93 g. The Oaxacan Big-toothed Deermouse is large, approaching a medium-sized woodrat ( Neotoma). It is similar in most charactersistics to Nelson's Bigtoothed Deermouse ( M. nelsoni) and Thomas's Big-toothed Deermouse (M. thomas), but there are relatively strong genetic differences among the three species. The Oaxacan Big-toothed Deermouse more closely resembles Nelson's Big-toothed Deermouse. Skull is broad, nasals are long, ears are small, and hindfeet are large. Dorsum is dark brown and thick,sides are ocherous, and belly is slate to infused with black-tipped hairs. Rostrum, cheeks, and orbital regions are black. Feet are silver and dark above ankles. Tail is long and dark. Nasals are particularly long, and zygomatic region is wide. The Oaxacan Big-toothed Deermouse differs from Thomas’s Big-toothed Deermouse by being darker and heavier bodied and by having wide rostral region.

Habitat. Known only from cloud forests and pine ( Pinus, Pinaceae) and oak ( Quercus, Fagaceae) forests, with thickly vegetated areas and dense understories of vines and shrubs, at elevations of 2400-3500 m.

Food and Feeding. Stomachs of Oaxacan Big-toothed Deermice have reportedly contained vegetation and berries. It probably eats seeds.

Breeding. Reproductively active males have been collected in April, June-July, and November. Lactating females have been caught in March, May, July, and November, suggesting that they are polyestrous. Litters are thought to have three young.

Activity patterns. The Oaxacan Big-toothed Deermouse is presumably nocturnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Endangered on The IUCN Red List. Endemic Oaxacan Big-toothed Deermouse has decreasing populations, and is considered endangered by the Federal government of Mexico.

Bibliography. Bradley et al. (2007), Carleton (1989), Musser (1964), Pena & Dominguez (2014a), Platt et al. (2015), Werbitsky & Kilpatrick (1987).