Cheirogaleidae

Diversity

There are 21 species in 5 genera in the family Cheirogaleidae. As with most Malagasy mammals, recent research has resulted in the naming of several new species in recent years. These are the smallest lemur species and are all arboreal, nocturnal, and social. They are all similar in ecology, with relatively restricted ranges and some variation in diets.

Geographic Range

Dwarf and mouse lemurs are restricted to forested regions of Madagascar.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Dwarf and mouse lemurs are found in forested habitats of different types, including evergreen, deciduous, and scrub forests. Mouse lemurs ( Microcebus ) are also found in suburban and agricultural areas. Dwarf and mouse lemurs rest during the day in tree hollows or rounded leaf nests in Microcebus and Mirza species.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest
• scrub forest scrub forest

• Other Habitat Features
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

Dwarf and mouse lemurs are the smallest lemurs, from 12 to 27 cm in length and 30 ( Microcebus berthae ) to 460 g ( Phaner furcifer ). Pygmy, or Berthe's, mouse lemurs ( Microcebus berthae ) are the smallest primates. Cheirogaleids have gray or brown dorsal pelage and lighter, creamy or yellowish pelage on their ventral surfaces. Some species have bold markings on their faces, such as eye rings or nose stripes. The fur is often thick and woolly. In general species in eastern Madagascar (more mesic forests) have reddish or brown fur and species in western Madagascar (more arid forests) have grayish fur. Dwarf and mouse lemurs are characterized by unusually long tails, ranging from about the length of the body to roughly half again as long; large, thin, and membranous ears; and well developed facial and carpal vibrissae. They have large, forward-facing eyes, reflecting their nocturnal lifestyle, compact bodies, and long, delicate fingers with rounded tips. In many species males are slightly larger than females.

Their hind feet have elongated calcaneus and navicular bones. As with other strepsirhines , they have a distinctive " toilet claw " on the second digit of their hind feet. Their thumb ( pollex ) is not as conspicuously separated from the other digits as in lemurs; and the third and fourth digits of both feet are similar in length.

Cranially, dwarf and mouse lemurs are defined by details of their cranial circulation and bullae . The frontal and palatal bones contact the orbit in most cheirogaleids. They have the typical strepsirhine tooth comb made up of lower incisors and canines , and their dental formula is 2/2, 1/1, 3/3, 3/3 = 36. In contrast to lemurs, their upper incisors are elongate. Hypocones are small are absent on the upper molars .

• Other Physical Features
• endothermic endothermic
• heterothermic heterothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike
• male larger

Reproduction

Some species are generally found in monogamous family groups ( Cheirogaleus , Phaner , Mirza ). Microcebus species occur in multi-male, multi-female social groups in which males pursue females when they are in estrous. Males use mating calls during the time of breeding. Females can have multiple male mates and give birth to litters with multiple paternity as a result. Females have distinct estrous cycles. In some species the vagina is sealed with a membrane when the female is not in estrous. A vaginal plug forms after copulation in some species. Estrous is signaled by swelling of the vulva.

• Mating System
• monogamous monogamous
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Dwarf and mouse lemurs breed seasonally, generally during the wet season from October to March. Smaller species can have multiple litters in a year, each with 2 to 3 young, larger species give birth to single offspring. Gestation is from 2 to 3 months and the young are cared for in a nest.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Females nurse their young regularly throughout the day, making it necessary for them to return to the nest throughout their nighttime foraging period.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Dwarf lemurs ( Cheirogaleus ) have been recorded living up to 23.2 years old and fork-marked lemurs ( Phaner furcifer ) have been recorded living up to 25 years in captivity. Longevity in the wild has not been well documented and is likely to be shorter than captive lifespans.

Behavior

Dwarf and mouse lemurs are all nocturnal and arboreal. They generally forage on their own, but roost during the day in small social groups and re-connect with other members of their social groups periodically throughout the night. Social organization varies among species, with some species ( Microcebus , for example) being found in multi-male, multi-female groups and others ( Cheirogaleus , for example) occurring in monogamous family units. Multi-male, multi-female groups are relatively loosely structured, with individuals having overlapping home ranges. Species that occur in relatively monogamous family units may cooperate to defend territories. Smaller species may become torpid occasionally and their body temperatures are labile, lowering when they sleep and rising when active. Fat is stored in the tail during rainy seasons to help individuals make it through dry seasons or times of torpor. Cheirogaleus species in arid habitats may aestivate for up to 6 months. Cheirogaleids get around with bipedal leaps and quadrupedal locomotion on branches.

• Key Behaviors
• arboreal arboreal
• scansorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• aestivation
• daily torpor
• territorial territorial
• social social

Communication and Perception

Individuals in social groups communicate with each other through scent marking and vocalizations. Scent marking involves leaving urine, feces, and gland secretions on trees and branches. Vocalizations include contact calls, alarm calls, and territorial defense calls, most are relatively high pitched sounds.

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Dwarf and mouse lemurs are generally omnivorous, eating fruits, insects, nectars, plant gums, and occasionally leaves and small vertebrates. Some species specialize on portions of that diet. For example, Cheirogaleus species eat mainly fruit and Phaner species specialize on plant gums and have a well-developed tooth comb in the lower jaw for this purpose. Most species forage mainly on the small branches of trees and shrubs below 10 m high, but they also forage on tree trunks, especially Phaner species, which have sharp claws on their digits to allow clinging to vertical surfaces. Phaner species also have an enlarged caecum to help them digest plant gums.

• Primary Diet
• omnivore omnivore

Predation

Predators of cheirogaleids are not reported in the literature, but are likely to include nocturnal predators, such as snakes ( Serpentes ), owls ( Strigiformes ), and fossas ( Cryptoprocta ferox ). They are nocturnal, cryptically colored, arboreal, and agile, all helping to decrease their vulnerability to predators.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Through their frugivory, cheirogaleids may help to disperse seeds. They also impact insect populations through predation.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Dwarf and mouse lemurs are too small to be hunted for food to a great extent. They may help to disperse seeds in forests and control insect pests to some extent.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

There are no adverse effects of dwarf and mouse lemurs on humans.

Conservation Status

Most dwarf and mouse lemur species are considered "data deficient" by the IUCN, primarily because many species are newly named and poorly understood. Of the 29 species recognized by the IUCN, 14 species are data deficient, 7 are least concern, 1 is near threatened, 2 are vulnerable, and 4 are endangered. Species considered least concern are still considered potentially vulnerable to habitat destruction and populations are thought to be in decline. Smaller species tend to be more common and widespread, larger species tend to have fragmentary distributions and are less common, therefore more threatened. Previously, all lemurs were considered endangered, so they are all listed on Appendix I of CITES.

Hairy-eared dwarf lemurs ( Allocebus trichotis ) were considered extinct until they were rediscovered in 1989.

Other Comments

There are no Cheirogaleidae fossils, although they are known from subfossil deposits on Madagascar. An Eocene fossil genus from Pakistan, Bugtilemur , is considered part of Cheirogaleidae.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (author), Animal Diversity Web.

Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.

References

Feldhamer, G., L. Drickamer, S. Vessey, J. Merritt. 1999. Adaptation, Diversity, and Ecology . Boston: WCB McGraw-Hill.

Groves, C. 1989. A Theory of Human and Primate Evolution . Oxford: Oxford Science Publications, Clarendon Press.

IUCN, 2009. "IUCN Redlist of Threatened Species" (On-line). Accessed July 27, 2009 at http://www.iucnredlist.org/ .

Martin, R. 2003. Dwarf lemurs and mouse lemurs ( Cheirogaleidae ). Pp. 35-45 in Grzimek Animal Life Encyclopedia , Vol. 14, 2nd Edition. Detroit: Gale Group.

Nowak, R., J. Paradiso. 1983. Walker's Mammals of the World, Fourth edition . Baltimore, London: John Hopkins University Press.

Szalay, F., E. Dodson. 1979. Evolutionary History of the Primates . New York: Academic Press.

Thorington, R., S. Anderson. 1984. Primates. Pp. 187-216 in Orders and Families of Recent Mammals of the World . New York: John Wiley and Sons.

Vaughan, T., J. Ryan, N. Czaplewski. 2000. Mammalogy, Fourth Edition . Philadelphia: Saunders College Publishing.

de Magalhães, J. 2009. "The animal ageing and longevity database" (On-line). Accessed July 27, 2009 at http://genomics.senescence.info .