Eulemur rufus is a relatively large lemur with a head-body length of 40–48 cm, a tail length of 45–55 cm, an overall length of 85–103 cm, and a mean body weight of around 2 kg (Gerson, 1999). This species is sexually dichromatic. In males, coloration is dark olive-gray with a deep brown tinge above and on the tail, and lighter below. The hands are red. The crown is dark brick-red, the cheek beard golden-red, and the muzzle black with an additional, broad, black midfacial stripe extending from the crown to the nose; the sides of the latter as well as the spots above the eyes are creamy-white. In females, coloration is gingery-red above with an orange underside and a short, golden-red cheek beard. The crown is black, and there are large, gray-white eye and cheek spots (Groves, 2001, 2006). There are no other members of the genus Eulemur throughout much of the range of the species, although there is a small hybrid zone with E. mongoz in northwestern Madagascar (Zaramody and Pastorini, 2001). The only species with which it is likely to be confused (in captivity) is E. rufifrons, with which it was considered conspecific until quite recently (Groves, 2006).
Many studies of “Eulemur rufus” carried out in the past (e.g., Sussman, 1974, 1975, 1977) are now attributed to E. rufifrons (C. P. Groves, pers. comm.). Eulemur rufus itself has not yet been the subject of a detailed behavioral or ecological study.
The rufous brown lemur is found in tropical dry lowland forests in west-central coastal Madagascar. It is patchily distributed from the Mahavavy du Sud River south at least to the Tsiribih.ina River. It may occur south of the Tsiribihina, but this is questionable. The northernmost recorded locality is Betsako, 15°35’S, 46°23’E; the southernmost, Beroboka, 19°58’S, 44°37’E (C. P. Groves, pers. comm.; C. Roos, pers. obs.).
Very little is known of the conservation status of E. rufus, so the 2008 IUCN Red List assessment classified it as Data Deficient (DD). It is found in three national parks (Baie de Baly, Tsingy de Bemaraha, and Tsingy de Namoroka), the Tsingy de Bemaraha Strict Nature Reserve, three special reserves (Bemarivo, Kasijy, and Maningoza), and in the Tsiombokibo Classified Forest (Nicoll and Langrand, 1989; Sterling and Ramaroson, 1996; Hawkins et al., 1998; Hawkins, 1999; Thalmann et al., 1999; Randrianarisoa et al., 2001; Goodman and Raselimanana, 2003). The numbers of this species in captivity are difficult to determine at this time, owing to taxonomic confusion with E. rufifrons. It is likely that most captive animals are E. rufifrons, but this remains to be verified.
The best place to see E. rufus is in the Tsingy de Bemaraha National Park, though it is also readily observed in Baie de Baly National Park. The Tsiombikibo Classified Forest near Mitsinjo is another possibility, although access can be difficult.