Microcebus myoxinus is one of the smaller mouse lemurs, with a head-body length of 12–13 cm, a tail length of 14–15 cm, a total length of 26–28 cm, and a body weight of 43–55 g (Rasoloarison et al., 2000). The dorsal coat is rufous-brown with a distinct reddish-brown midline stripe. The ventral coat is pale yellow-brown to pale gray in color. The tail is darker toward the tip. The ears are relatively short. A light cinnamon patch between the eyes darkens to reddish behind the orbits and to a tawny crown and ears. The dark eyebrows are prominent. Furred portions of the hands and feet are whitish-gray to whitish-beige.
Although this species may be sympatric with other mouse lemurs, it is difficult to give precise information on how to distinguish between them. Since some of the sympatric species may still be undescribed, further research on western mouse lemurs is clearly needed. In addition, Microcebus myoxinus is sympatric with several other nocturnal genera, including Cheirogaleus, Mirza, Phaner, and Lepilemur, but can be distinguished from them by its smaller size.
Microcebus myoxinus has been found in tropical dry deciduous lowland forests (sea level to 900 m) in the Tsingy de Bemaraha Strict Nature Reserve and the Andramasy forests north of Belo-sur-Tsiribihina, along the border of heavily degraded deciduous forest and savanna at Aboalimena, and in mangrove forests in the Baie de Baly region (Hawkins et al., 1998; Rasoloarison et al., 2000). Its ecology and behavior remain to be studied.
West-central Madagascar. Peters (1852) returned from a collecting expedition to Madagascar with three western mouse lemur specimens that he named M. myoxinus, but Schwarz (1931) later declared them synonymous with Microcebus murinus. Schmid and Kappeler (1994) later concluded that two mouse lemur species were present in the Kirindy Forest north of Morondava, one of them a smaller rufous animal for which they resurrected the name M. myoxinus. Re-examination of the specimens collected by Peters (1852) indicated that the Kirindy animals were not M. myoxinus, but rather an entirely new species that was named Microcebus berthae Rasoloarison et al., 2000, and that the name M. myoxinus actually applies to populations found farther north.
Microcebus myoxinus is reported to range from the
north bank of the Tsiribihina River north to Baie de Baly
in western Madagascar, and to occur in the forests of Belo-
sur-Tsiribihina and Aboalimena, the Tsingy de Bemaraha
National Park and Strict Nature Reserve, and the Tsingy de Namoroka National Park. In Tsingy de Namoroka and Baie de Baly, it occurs in sympatry with M. murinus (see Hawkins et al., 1998; Rasoloarison et al., 2000; CBSG, 2002). In Tsingy de Bemaraha National Park, this species is sympatric with at least one other form of Microcebus that remains to be identified (Rakotoarison et al., 1993; Thalmann and Rakotoarison, 1994; Ausilio and Raveloarinoro, 1998).
There is insufficient information to determine the conservation status of M. myoxinus, and the latest IUCN Red List assessment (2008) classified it as Data Deficient (DD). It occurs in two national parks (Tsingy de Bemaraha and Tsingy de Namoroka), the Tsingy de Bemaraha Strict Nature Reserve, and likely in Baie de Baly National Park as well, but little is known of its populations in these areas.
As of 2009, this species was not being kept in captivity (ISIS, 2009).
The best chances for seeing M. myoxinus in the wild are in the Tsingy de Bemaraha, where there are now two lodges to accommodate visitors. Excursions to the area can be arranged through the Hotel Chez Maggie in Morondava or through most Antananarivo- based tour operators. However, distinguishing it from the sympatric, possibly undescribed, species may be difficult.