Lepilemur dorsalis is a small sportive lemur with a head-body length of 23–26 cm, a tail length 26–28 cm, a total length of 51–54 cm, and an average weight of 500–730 g (Louis et al., 2006b). The ears are relatively short and rounded, the muzzle blunt, and the face dark gray to brown. The dorsal coat, including the tail, is medium brown to gray-brown and bisected by a darker brown median stripe. The ventral coat is a lighter gray-brown, paler towards the throat. This species might be confused with Cheirogaleus medius and Avahi unicolor. It can be distinguished from Cheirogaleus by its larger size, vertically-oriented posture, and clinging-leaping form of locomotion. It can usually be distinguished from Avahi by its more prominent ears. Avahi also has larger, owl-like eyes, a woollier appearance, and distinctive white patches on its thighs, and often huddles closely with other family members. The precise taxonomy of the sportive lemurs of northwestern Madagascar, and their relationship to each other, remain undetermined. Zinner et al. (2007) showed that the three teams which described new Lepilemur species there in 2006 and 2007 (Andriaholinirina et al., 2006a; Louis et al., 2006b; Craul et al., 2007) each had different concepts of L. dorsalis, and that the validity of Lepilemur tymerlachsonorum vs. Lepilemur mittermeieri in particular depends on which concept turns out to be correct. The type locality of L. dorsalis ie either Mourountsang (= Anorantsangana, 13o55’S, 47o55’E) or Passandava (= Ampasindava, about 13o40’S, 48o15’E). If the former, then L. tymerlachsonorum is a synonym of L. dorsalis and L. mittermeieri is valid. The species found at Anorontsangana is also found on Nosy Be (Zinner et al., 2007). The name Lepilemur grandidieri (Forsyth Major, 1894) was given to a species from this general area, and this too may prove to be a senior synonym of one of the species described in 2006/2007 (C. P. Groves, pers. comm.).