Lepilemur ankaranensis is one of the smaller sportive lemurs, with an average head- body length of 22 cm, a tail length of 27 cm, a total length of 49 cm, and a body weight of 750–790 g (Louis et al., 2006b). The description that follows is based on specimens that had previously been assigned to Lepilemur septentrionalis, a species that evidently has a much more restricted range than previously believed (Ravoarimanana et al., 2004; Rumpler, 2004). The overall color is a light grayish-brown above with a gray underside. There is often a dark median stripe extending from the crown of the head along the spine, as well as brownish tinges in the shoulder region. The tail is pale brown, darkening towards the tip. The ears are less prominent than those of other Lepilemur species. This species might be confused in the field with Phaner or Cheirogaleus if only a fleeting glimpse of the animal is obtained, and also with Avahi even under good conditions. Its vertical posture, prominent ears, darker abdomen and leaping locomotion readily distinguish it from the smaller, more quadrupedal Cheirogaleus. Phaner has a distinctive fork-marked pattern on the forehead, a more elongated face, moves more rapidly and continuously, and produces distinctive, loud vocalizations. Avahi is similar in size and posture to Lepilemur, but has much smaller ears and distinct white patches on its thighs, and often huddles closely with other family members.
The natural history of L. ankaranensis remains relatively poorly studied. Information on its behavior and ecology can be drawn from studies on sportive lemur populations previously assigned to L. septentrionalis. Population densities have been estimated at 150–550 individuals/km2 (Ratsirarson and Rumpler, 1988; Hawkins et al., 1990), and a typical range size seems to be about one hectare. Adults remain solitary during nightly bouts of foraging for leaves. Tree holes and vine tangles are preferred daytime shelters. The Madagascar ground boa (Acrantophis madagascariensis) is known to prey upon sportive lemurs in their sleeping sites.
Northern Madagascar. This species is found in the tropical dry lowland forests of Ankarana, Andrafiamena and Analamerana, and the tropical moist montane forests of Montagne d’Ambre, occurring from low elevations up to 1,500 m (Rumpler et al., 2001; Ravaoarimanana et al., 2004; Rumpler, 2004). It appears to be sympatric with L. milanoii in the Andrafiamena Classified Forest, and fields studies are needed to determine how these two species co- exist there; the only place where two Lepilemur species live in the same forest (Louis et al., 2006b).
The most recent IUCN Red List assessment (2008) classified L. ankaranesis as Endangered (EN). The principal threats are forest destruction for charcoal production and hunting for food. Hunting has become more important in recent years, with the appearance of large numbers of itinerant sapphire miners in the Ankarana region. The species is found in two national parks (Ankarana and Montagne d’Ambre) and two special reserves (Analamerana and Fôret d’Ambre), as well as in the Andrafiamena Classified Forest, which is slated to become a national park. As of 2010, this species was not being kept in captivity (I. J. Porton, pers. comm.).
This species is readily seen in both Montagne d’Ambre National Park (especially near the Station des Rousettes) and in Ankarana National Park, where it can be quite visible and vocal at certain times of the year. In the latter, it can be observed in the Canyon Forestier, the Campement des Anglais, and in forests near the Mahamasina entrance (Garbutt, 2007; R. A. Mittermeier, pers. obs.).