Its scientific name literally means "cold-lover". This refers directly to its inhabiting the highest, coldest coniferous forest zones of the Oaxaca mountains, above the altitude where most of its rodent relatives in the region can survive.
The Oaxacan Big-toothed Deermouse is one of the largest mice in Mesoamerica. Its teeth are notably large for its group, a trait that gives its entire genus its
A large rodent for a Mesoamerican muridae. It has dark brown fur, large ears, and teeth remarkably developed in proportion to the skull, a distinctive feature of its entire genus. It differs from other mountain forest rodents in Oaxaca by its larger size and by living at the highest and coldest elevations in the region, above where related, lower-altitude species are found.
Track with 4 front toes and 5 hind toes; hind track 2-2.5 cm long, somewhat larger than those of other forest rodents in the same area due to its larger body size. Elongated droppings, 8-10 mm long, left scattered along paths under dense undergrowth. It builds nests of grass and moss in hollows under fallen logs or roots, in the damp soil of the high-mountain pine forest where it lives.
High-mountain pine forest with dense undergrowth and a cold climate, generally above 3000 m altitude. Endemic to the highest elevations of the Sierra Madre de Oaxaca in southern Mexico.
Omnivorous, it feeds on seeds, fruits, fungi and invertebrates from the soil of high-mountain pine forest.
Terrestrial, with solitary and territorial behaviour, it is adapted to the constant cold conditions of the highest elevations of its range. It is probably nocturnal, like other rodents in its genus.
Its restriction to the highest and coldest altitudes of a single mountain range, together with the continued loss of high-mountain pine forest, place its populations in continuous decline with very little scope for altitudinal shift.
Deforestation of high-mountain pine forest due to logging, and the altitudinal displacement of necessary cold conditions associated with climate change, pose an especially serious risk. This is particularly grave for the Oaxacan Big-toothed Deermouse, which is already confined to the highest available altitudes.
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