The Ixtlán Deermouse lives in a single mountain massif in the Sierra Norte de Oaxaca. This is one of many examples of endemic rodents with extremely restricted distributions, generated by the geographical isolation of the various mountain ranges forming that region of southern Mexico. Like others in its genus, the Ixtlán Deermouse spends much of its life climbing among the understorey vegetation of cloud forest, aided by a long, prehensile tail which it uses as an additional point of support when moving among branches and elevated leaf litter. Its name alludes to the Ixtlán region, in the heart of the Sierra Norte de Oaxaca, the locality where the species was first documented. Its very restricted home range and strong dependence on cloud forest make the Ixtlán Deermouse one of the Mexican rodent species at greatest risk of disappearing, with hardly any of its basic biology known.
Small rodent, with greyish-brown fur on the back and paler on the belly, large prominent eyes, well-developed ears, and a long, prehensile tail. It can be confused with other species of arboreal mice from the same genus in the mountains of Oaxaca. Reliable separation requires genetic or cranial analysis, given the group's recent taxonomic resolution.
A small track, 1.5-2 cm long, with 4 front toes and 5 hind toes, rarely visible as its climbing habit keeps it off bare ground. Small, elongated droppings, 4-6 mm long, left scattered through low vegetation and the elevated leaf litter of the undergrowth. It builds spherical nests of grass and moss among dense vegetation or in tree hollows, above ground level.
Mountain cloud forest with dense undergrowth and abundant epiphytic vegetation, generally between 2000 and 3000 m altitude. Endemic to a very small area of the Sierra Norte de Oaxaca in southern Mexico, in the Ixtlán region.
Omnivorous, it feeds on seed, fruit, fungus and invertebrate from the undergrowth, also utilising available resources among the elevated epiphytic vegetation.
Arboreal and climbing, the Ixtlán Deermouse moves through low and high undergrowth vegetation using its prehensile tail. It is probably nocturnal. Its solitary behaviour is poorly documented due to the scarcity of studies on the species.
Its populations are in marked decline due to the continued loss of the cloud forest, on which it is strictly dependent. This mountain ecosystem is already reduced and fragmented in the Sierra Norte de Oaxaca.
Deforestation and fragmentation of cloud forest due to agricultural and livestock expansion, and the altitudinal displacement of the humidity conditions necessary for this ecosystem associated with climate change.
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