THE INDRIIDAE:A LIFE HISTORY by Mary Deborah Robinson Dr. Steve Herman Vertebrate Biology The Evergreen State College Olympia, Washington Fall Quarter, 1980 The Indriidae (Burnett, 1828) by Mary Deborah Robinson :- •- Avahi (Jourdan, 1834) Propithecus (Bennett, 1832) Tndri (E. Geoffroy and Cuvier, 1795) CONTEXT AND CONTENT. Order Primates. Suborder Prosimii. Infraorder Lemuriformes. Superfamily Lemuroidea. Family Indriidae. This classification follows Simpson, 1945. Also in use is a taxonomic order suggested by Hill, 1953, which introduces a Grade, Strepsirhini, before the proposed Suborder, Lemuroidea. Another scheme was proposed by Romer, 1967, which makes Lemuroidea a Suborder, but lumps the Indriidae with the Family Daubentoniidae, of which there is one extant species, the Aye-Aye. Tattersall suggests that there are three subfamilies: Indriinae, with living representatives, and the extinct Archaeolemurinae and Palaeopropithecinae. Szalay describes a slightly different group of the extinct forms; both ideas will be reviewed later. This paper deals primarily with the extant forms. There are three living genera, four species and twelve subspecies. Avahi laniger (Gmelin, 1788) type species. Propithecus diadema (Bennett, 1832) type species. Propithecus verreauxi (A. Grandidier, 1867) type species. Indri indri (Gmelin, 1788) type species. CONTEXT AND CONTENT. As described above, however there are two generally agreed upon subspecies of Avahi and ten described species of Propitheci. Avahi laniger laniger (Gmelin, 1788) Dark reddish color, lives in most humid eastern forest of Madagascar and is particularly common in the coastal region. A. 1. occidentalis (Lorenz, 1898) Light reddish grey coloring with white thighs living in forests of western Madagascar and in the southwest. Propithecus diadema (Bennett, 1832) Head to base of tail about 50 cm. Vocalization is a series of cries from growls to hoarse barks uttered in unison. Name in Malagasy is "chim-poun" which appears to be an imitation of the growl. Males have a gland near the skin surface visible at the join between the chest and neck. It is used for marking territory. The animals have a thick coat. There are several forms scattered from North to South along the eastern coast of Madagascar. According to Petter, they are as follows: P_._ d. perrieri (Lavauden, 1931) Black coat, Far North. P_._ d_._ candidus (Grandidier, 1871) White coat, head lightly tinged with grey, lives in Sambava-Andapa region. P. d_._ diadema (Bennett, 1832) Grey coat, black head, limbs tinged with yellow, lives between Mananara and Tamatave. P_._ d. edwardsi (A. Grandidier, 1871) Chocolate brown coat on limbs, head, upper part of back and tail, color turns to beige on front of body. Lives in central part of eastern forest. P_. d. holomelas (Gunther, 1875) Black coat turning to brownish on front with lighter colored triangle at the base of the spine. Idanadiana region. The Indriidae -2- 1 M. Robinson X'*B.,- Propithecus verreauxi (A. Grandidier, 1867) This animal is smaller than P. d., also thinner with a sparser coat and distributed throughout western Madagascar. The Malagasy name for tine species is "chi-fac" imitating the wheezing noise the lemur makes when disturbed. The common name for all Propitheci is Sifaka after this vocalization. These animals are very trusting, extremely affectionate, and have no defenses. They are rapidly disappearing. The subspecies, according to Fetter, are listed below. p. y_._ cocfuereli (A. Milne Edwards, 1867) White coat, bright reddish brown spots on upper part of thighs and arms, brownish stomach, black face, golden eyes. Ankarafantsika region of Madagascar. P. v. deckeni (Peters, 1870) White all over. Antsalova-Soalala region. P. v. coronatus (A. MilntuEdwads, 1871) White coat tinged with pale grey on back, red on chest, black head. Between Majunga and Soalala P_._ v. verreauxi (Grandidier, 1876) White all over, top of head dark brown with white band on forehead. Found between south and southwestern region of Madagascar. P. v. majori (Rothchild, 1894) Similar to P. v. v., but much black coloring on upper part of arms, thighs and back. Southwest, particularly in Sakaraha region. Possibly extinct. DIAGNOSIS. The following characters are diagnostic of both genus and species: extended hallux; intermembral index short; pelage long, although face inevitably black and sparsely haired; dental formula is 2.1.2.3 with a tooth comb composed of one pair of incisors 2.0.2.3 and the canines; indriids have large hypocones on the upper molars. The face and mandible are usually foreshortened, and mandibular angle is expanded. Hands are finely elongated; on their feet they have a toilet claw. Cutaneous glands run vertically along the throat. Their diet is folivorous and frugivorous. Powerful hindlimbs propel their vertical climbing and leaping locomotion. These arboreal lemurs are the largest living prosimians. They are bipedal on the ground. Primarily diurnal, their distinctive vocalizations are heard only on the island of Madagascar. Gregarious, the animals are found usually in family groups. GENERAL CHARACTERISTICS. With the exception of the Avahi, these large lemurs are diurnal, leaping from tree trunk to tree trunk. Recorded bounds are between 30 and 40 feet. Characteristically the animal takes off on long leaps in a head first dive with the arms over the head and reverses itself in mid-leap, landing feet first, followed by hands, in a vertical position. For small leaps the animals push off and land holding the body vertical throughout. On the ground the lemurs run and leap bipedally with the arms carried over the head. Indriidae possess long silky dense fur with distinctive patterns by which it is believed individuals are identified. The lemurs appear to be equally dependent upon vision, olfactory sense, and hearing. Indriidae feed primarily upon leaves, supplemented by fruit, flowers and bark. They are vocal and territorial, living in groups of between 2-6 individuals which always contain an adult of either sex and young. The Indriidae — 3 — M. Robinson GENERAL CHARACTERISTICS (Cont'd). The Indriidae breed seasonally, bearing their young between July and September after a relatively long gestation period of five months. Infants are born with eyes open, a thin covering of hair, and the ability to grasp their mother's fur. They hang horizontally across their mother's stomach, below the pair of pectoral mammaries. After one month the infant will move to the mother's back and remain there until six months old. Infants are very attractive to adult Indriidae who spend much time grooming them. Indriidae are mature at approximately two and one half years. Adults spend most of their time eating and resting in the forks of trees. These animals communicate with extensive vocalizations and complicated behaviors which include grooming and playing. Indri indri is the largest family member with a head and body length of 700 mm and a stubby tail approximately 30mm. Standing bipedally with its arms over the head, its proportions ressemble a human. It has a longer, blunter snout than Propitheci, a rounded head shape, and small but obvious rounded ears. Occupying crests in the medium altitude areas of the eastern forests, at the slightest alarm it departs for the valleys with spectacular leaps like an arboreal kangaroo. Its cries include loud warning barks and varied growls. When calm a family on a hill will take up long modulated calls with individual family members singing in harmony. These calls carry long distances, and when one group is finished, a neighboring groups will begin. Indri are believed to be monogamous, and female dominant, reproducing once every three years. The animals have 40 chromosomes (Rumpler and Albignac, 1973c). The long hindlimb bears a very divergent toe. There is no dimorphism in size or color which varies as follows (Burton, 1969). The general color is black and white. The head, neck, shoulders, back, arms, and hands are black. The rump extending up the back is white, washed with reddish flanks. The insides of the thighs are grey, but the outside of the hindlimbs is black, as is .the face. Variations include (a) the top of the head all white with throat and legs grey, and flanks and heels being bright red; (b) a patch of grey over each eye, and grey forelimbs, shanks and undersides; (c) pure white albinos with pink eyes. Normally the eyes are large, yellow-brown in color with circular pupils (Napier, 1973). Related to the large Indri is the Avahi laniger or WooljLy Indri. This is the smallest of the indriidae with a soft, thick woolly fur which has an overall grey appearance although the individual hairs change from grey at the base to brown to black at the tip (Napier, 1973) There is a white band on the forehead, and the underparts are grey or white with a rufous tinge. The tail, hands and feet are rust colored The Avahi has a rounded, naked face with a short muzzle. The ears are small and hidden. The eyes are very large with a pupil forming a vertical slit. The animal is nocturnal and spends the day curled up in dense undergrowth either in the fork of a tree or clinging to a branch. It has long slender hands and feet. In both extremeties, .: • (Z.96T ' -, The Indriidae -4- M. Robinson - GENERAL CHARACTERISTICS (cont'd)the 3rd, 4th and 5th digits are webbed. The big toe is widely divergent. Like the other indriidae, the second toe is modified into a "toilet claw." The head and body length is between 300 - 330 mm and the tail length is longer than the body length, between 390-395 mm. Avahi possesses 64 chromosomes. It is strictly an arboreal vegetarian, occurring singly or in pairs and found primarily near the southeastern coast. Propithecus, the Sifaka or monkey lemur, is medium sized. Its head and body length are between 458 - 534mm and the tail length ranges between 485-560 mm (Napier, 1973).