Microcebus griseorufus is a large mouse lemur, 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 46–79 g (Rasoloarison et al., 2000). The dorsal coat is light gray, split by a cinnamon midline stripe that runs from either the crown or the shoulders to the end of the tail, which is largely cinnamon above and beige beneath. The anterior portion of the ventral coat is light grayish- white, the posterior portion tending more toward gray.
An inhabitant of the spiny forest of southern Madagascar, this species is sympatric in some areas with M. murinus, from which it can readily be distinguished by its more prominent, darker mid-dorsal stripe (Rasoloarison et al., 2000; Goodman et al., 2002; Yoder et al., 2002; Ganzhorn and Randriamanalina, 2004). It is often in the same forests with two other nocturnal genera, Cheirogaleus and Lepilemur, as well, and can easily be distinguished from both of these by its much smaller size and more rapid movements.
Microcebus griseorufus is a common inhabitant of spiny
forest and dry thorn scrub from sea level to 250 m. In the
Beza-Mahafaly Special Reserve it is also found in gallery forest, while in the Berenty Private Reserve it is replaced in that habitat by M. murinus (see Rasoazanabary, 2004). In Beza-Mahafaly and in the nearby Ihazoara Valley, both species are among the prey of the Barn Owl (Tyto alba) and the Madagascar Long-eared Owl (Asio madagascariensis) (Goodman et al., 1993a, 1993b). This species feeds mainly on gums, especially during periods of drought. Daily torpor and opportunistic seasonal fattening have been observed when food availability is high (Génin, 2008).
The reproductive season is relatively long, lasting as it does from September to May. Estrus is not synchronized. Mating occurs between September and January. Males have been observed to mate-guard. Gestation in one female lasted 52 days, and litters of up to three have been reported. Alloparenting has been observed. Young males disperse. Females and, less frequently, males associate in same-sex pairs that sometimes combine to form larger sleeping groups (Génin, 2008).
Kollman (1910) described the new subspecies Microcebus minor griseorufus from southern Madagascar. Tattersall (1982) considered it to be a synonym of M. murinus. In a recent review of the genus, Rasoloarison et al. (2000) elevated it to a full species as M. griseorufus. It is found in the spiny forest region of southern and southwestern Madagascar, where it ranges from Lamboharana south to the Toliara (= Tuléar) region, to the Beza-Mahafaly Special Reserve (south of the Onilahy River) in the southeast, and to Tsimanampetsotsa, Berenty, and Petriky in the extreme south. At Beza-Mahafaly and Mikea it is sympatric with M. murinus, whereas in Berenty it is found in spiny forest patches but not in the immediately adjacent gallery forest that is occupied by M. murinus.
Microcebus griseorufus was classified as Least Concern (LC) in the most recent IUCN Red List assessment (2008). The most significant threats to its survival are deforestation for charcoal production and land clearance for commercial maize production. This species is known to occur in the Tsimanampetsotsa National Park, the Beza-Mahafaly Special Reserve, and the Berenty Private Reserve, and may also be present in two other national parks (Isalo and Zombitse-Vohibasia).
As of 2010, this species was not being kept in captivity (I. J. Porton, pers. comm.).
The easiest place to see this mouse lemur is in the spiny forest patches of the Berenty Private Reserve, where it is quite common. Another good place is the Beza-Mahafaly Special Reserve, located 35 km northeast of Betioky Sud, about a five-hour drive from Toliara (= Tuléar) in a four-wheel-drive vehicle (Bradt, 2007; Ratsirarson, 2003). Microcebus griseorufus may also be readily observed in the forest called “PK 32” near Ifaty, north of Toliara, and in Tsimanampetsotsa National Park. Night walks at PK 32 are possible from many of the hotels in the Ifaty Mangily coastal tourism area, one hour north of Toliara. Tsimanampetsotsa National Park is a two-hour drive from Anakao (another coastal tourist spot with several hotels), and a 45-minute boat ride south of Toliara.