Jourdan, 1834
General characteristics
The genus Avahi consists of two species: Avahi laniger (Avahi laniger 1) and Avahi occidentalis (Avahi occidentalis 1). Those are the smallest species of the family Indriidae.
Their morphological anatomy, postures and locomotion resemble those of Propithecus and Indri. They surely differ by their small size and their strictly nocturnal habits.
Sometimes very abundant, but always very discrete, these animals live in small groups of two or three individuals. Avahi is nocturnal and folivorous. There are two species, one (Avahi laniger) found throughout the eastern rain forest and the other (A. occidentalis) with a more restricted distribution in the northwest of Madagascar. Both species used to be more widely distributed than they are today (Tattersall, 1982). They can reach rather large population densities. Avahi laniger has a dark pelage and Avahi occidentalis has a bright pelage and is of slightly smaller size.
They have a dense pelage, with a wooly appearance. The hairs tend to form short curls on the back and the thighs. The general color is dark red for the eastern form and reddish gray for the western form. A bright red spot marks the base of the back. The inner parts of the tights are bright. The eyebrows are more or less brightly colored. They are white with the western form from which its Malagasy name originates. The tail is red. The two forms possess only very small differences, apart from the pelage differences.
Sometimes still used by certain authors, the generic names Lichanotus Illiger, 1811 and Lichanotes Temminck, 1827 are synonyms of the genus Indri. The generic name Microrhynchus, proposed by Jourdan, 1834, was already used by Dejean in 1821 for the Coleoptera.
Besides, other generic names have been proposed: Avahis I. Geoffroy, 1835, Habrocebus Wagner, 1839, Iropocus Gloger, 1841 and Semnocebus Lesson, 1840.
Systematics
Avahi was observed for the first time by Sonnerat and was named the 'maquis à bourre' (Sonnerat pl89). The two forms were excellently depicted in Grandider, 1875 (Grandidier pl09)(Grandidier pl10).
The two forms of Avahi were formerly considered to be subspecies:
Avahi laniger laniger (Gmelin, 1788) and Avahi laniger occidentalis Lorenz, 1898, but are actually regarded as species after cytogenetic research by Rumpler et al., 1990: Avahi laniger (Gmelin, 1788) and Avahi occidentalis Lorenz, 1898 (Karyo A. laniger; Karyo A. occidentalis).