Fork-marked lemur

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Fork-marked lemurs
Phaner pallescens 1985.JPG
Pale fork-marked lemur (P. pallescens)
Conservation status
CITES Appendix I (CITES)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Infraorder: Lemuriformes
Family: Cheirogaleidae
Genus: Phaner
Gray, 1870
Type species
Lemur furcifer
de Blainville, 1839[2]
Species

Phaner furcifer
Phaner pallescens
Phaner parienti
Phaner electromontis

Map of Madagascar, off the southeast coast of Africa, with a range covering parts of the west, northwest, north, and northeast.
Distribution of Phaner:[3]

red = P. furcifer; green = P. pallescens;
purple = P. parienti;
orange = P. electromontis

Fork-marked lemurs or fork-crowned lemurs are nocturnal strepsirrhine primates, with four species comprising the genus Phaner. Like all other lemurs, they are native to Madagascar, but found only in the west, north, and east sides of the island. They are named for the two black stripes which run up from their eyes, converge on the top of their head, and run down the back as a single black stripe. Originally placed in the genus Lemur in 1839, they were later moved to the genus Cheirogaleus, and finally given their own genus in 1870 by British zoologist John Edward Gray, who named it after a character in the British comedy The Palace of Truth by W. S. Gilbert. Only one species (Phaner furcifer) was recognized until three new subspecies—described in 1991—were promoted to species status in 2001. New species may yet be identified, particularly in northeast Madagascar.

Fork-marked lemurs are among the least studied of all lemurs and are some of the largest members of the family Cheirogaleidae, weighing around 350 grams (0.77 lb) or more. Aside from their dorsal forked stripe, they have dark rings around their eyes, and large membranous ears. Males have a scent gland on their throat, but only use it during social grooming, not for marking territory. Instead, they are very vocal, making repeated calls at the beginning and end of the night. Males usually pair up with females to form monogamous pairs, and females are dominant. They sleep in tree holes and nests. Females have only one offspring per year.

They live in a wide variety of habitats, ranging from dry deciduous forests to rainforests and run quadrupedally across branches. Their diet consists primarily of tree gum and other exudates, though they obtain their protein and nitrogen by hunting small arthropods later at night. Three of the four species are endangered and the other is listed as vulnerable. Their populations are in decline due to habitat destruction. Like all other lemurs, they are protected against commercial trade under CITES Appendix I.

Taxonomy[edit]

Fork-marked lemurs were first documented in 1839 by French zoologist Henri Marie Ducrotay de Blainville when he described the Masoala fork-marked lemur (P. furcifer) as Lemur furcifer.[4] Prior to 1867, it had been moved to the genus Cheirogaleus (dwarf lemurs),[5] but was given its own genus, Phaner, by British zoologist John Edward Gray in 1870 within the family Cheirogaleidae. Until the late 20th century, there was only one species of fork-marked lemur,[4] although size and coloration differences had been noted previously.[6] After comparing museum specimens, paleoanthropologist Ian Tattersall and primatologist Colin Groves recognized three new subspecies (P. f. pallescens, P. f. parienti, and P. f. electromontis) in 1991,[4][7] and in 2001, Groves elevated all four subspecies to species status.[4][8]

There are currently four recognized species:[4][9]

In December 2010, Russell Mittermeier of Conservation International and conservation geneticist Edward E. Louis, Jr. from the Omaha's Henry Doorly Zoo announced the possibility of a new species of fork-marked lemur in the protected area of Daraina in northeast Madagascar. In October, a specimen was observed, captured, and released, although genetic tests have yet to determine if it is in fact a new species. The specimen demonstrated a slightly different color pattern and an unusual head-bobbing behavior for fork-marked lemurs. If confirmed as a new species, they plan to name it after Fanamby, a key conservation organization working in that protected forest.[9][10]

Etymology[edit]

The etymology of the genus Phaner puzzled researchers for many years. Gray often created mysterious and unexplained taxonomic names—a trend not only continued with his description of Phaner in 1870, but also with the genera Mirza (giant mouse lemurs) and Azema (for M. rufus, now a synonym for Microcebus), both of which were described in same publication. In 1904, American zoologist Theodore Sherman Palmer attempted to document the etymologies of all mammalian taxa, but could not definitively explain these three genera. For Phaner, he only noted that it derived from the Greek φανερός (phaneros) meaning "visible, evident". In 2012, Dunkel et al. attempted to solve the mystery, initially speculating that Gray had been referring to the "prominent" first upper premolar. However, they also noted Gray's tendency to use puns when creating generic names, so they also speculated that the name might also be a pun on the word "feigner" (pretender) since he initially thought fork-marked lemurs belonged to Lepilemur (sportive lemurs) based on their premolars—an opinion that Gray changed in the appendix, where he viewed Phaner furcifer (Masoala fork-marked lemur) as a "feigned" Lepilemur.[11]

Because Mirza (derived from the Persian title mīrzā, meaning "prince") might have come from Arabian Nights, a popular piece of literature at the time, Dunkel et al. also searched the general literature published around 1870. The answer to all three names was found in a British comedy The Palace of Truth by W. S. Gilbert, which premiered in London on 19 November 1870, nearly one and a half weeks prior the date written on the preface of Gray's manuscript (also published in London). The comedy featured characters bearing all three names: King Phanor (sic), Mirza, and Azema. The authors concluded that Gray had seen the comedy and then based the names of three lemur genera on its characters.[11]

Fork-marked lemurs were originally called "fork-marked dwarf lemurs" by Scottish naturalist Henry Ogg Forbes in 1894 and "fork-crowned mouse lemur" by English naturalist James Sibree in 1895. Literature searches by Dunkel et al. also uncovered other names, such as "fork-lined lemur" and "squirrel lemur", during the early 1900s. However, by the 1970s reference to dwarf and mouse lemurs had ended, and the "fork-crowned" prefix became popular between 1960 and 2001. Since then, the "fork-marked" prefix has become more widely used.[11]

Description[edit]

Of the mostly small, nocturnal lemurs in family Cheirogaleidae, genus Phaner contains some of the largest species, as well as Cheirogaleus (dwarf lemurs).[4] Their body weight ranges between 350 and 500 g (0.77 and 1.10 lb),[12] and their head-body length averages between 23.7 and 27.2 cm (9.3 and 10.7 in), with a tail length between 31.9 and 40.1 cm (12.6 and 15.8 in).[13]

Males have a scent gland of their throat, which they only use during allogrooming

Their dorsal (back) fur is either light brown or light grayish-brown, while their ventral (underside) fur can be yellow, cream, white, or pale brown.[4][6] A black stripe extends from the tail, along the dorsal midline to the head, where it forks at the top of the head in a distinguishing Y-shape leading to the dark rings around both eyes, and sometimes extends down the snout. The dorsal stripe varies in width and darkness,[4][14] and the base tail is the same color as the dorsal fur[12] and is usually tipped in black[4][12] and bushy.[12][15] Their ears are relatively large and membranous.[15] Males have a scent gland on the middle of their throat,[12] which is approximately 20 mm (0.79 in) wide and pink in color. Females have a narrow, bare patch of white skin in the same location, but theirs does not appear to produce secretions.[16]

Fork-marked lemurs have relatively long hindlegs. For gripping tree trunks and large branches, it has large hands and feet with extended pads on the digits, as well as claw-like nails.[15][17] They have a long tongue which assists obtaining the gum and nectar,[15][17] as well as a long caecum, which helps digest gums.[4][15] Their procumbent (forward-facing) lemuriform toothcomb (formed by the lower incisors and canines) is long[17] and more compressed, with significantly reduced interdental spaces to minimize the accumulation of gum between the teeth.[18] Their anterior premolars are caniform (canine-shaped),[15][17] while the next premolar is very small. The genus is also distinguished from other cheirogaleids by the toothrows on its maxilla (upper jaw), which are parallel and do not converge towards the front of the mouth.[8] Their upper first incisor (I1) is long and curved towards the middle of the mouth (unique among lemurs),[8][19] while the second upper incisor (I2) is small with a gap (diastema) between the two.[19] The upper canines are large, with their tips curved.[8][19]

Distribution and habitat[edit]

Fork-marked lemurs are found in the west, north, and east of Madagascar, but their distribution is discontinuous.[4][15] Their habitat ranges from dry deciduous forests on the western coast of the island to rainforest in the east.[17] They are also commonly found in secondary forest, but not in areas lacking continuous forest cover.[1] They are most common in the west of the island.[15] Fork-marked lemurs are not found in the southern spiny forests in the dry southern part of the island, and only recently have been reported from the southeastern rainforest at Andohahela National Park, though this has not been confirmed. A team led by E. E. Louis Jr. has also suggested that undescribed varieties may also exist elsewhere on the island.[4]

The Masoala fork-marked lemur is found on the Masoala peninsula in the north-east of the island, [20] while the Amber Mountain fork-marked lemur is in the far north of the island found, particularly at Amber Mountain National Park.[21] Pariente's fork-marked lemur, found in the Sambirano region in the north-west,[22] and the Pale fork-marked lemur is in west of the island.[23]

Behavior[edit]

Fork-marked lemurs are arboreal and nocturnal.

Fork-marked lemurs are among the least studied of all lemurs, and little is known about them.[4] Only the pale fork-marked lemur (P. pallescens) has been studied relatively well, primarily during two expeditions in the 1970s and a more extensive 1998 study in Kirindy Forest.[24] Like the other cheirogaleids, they are nocturnal, sleeping in tree hollows (typically in large baobab trees) or abandoned nests built by giant mouse lemurs (Mirza coquereli) during the day[1][15][25] and searching for food at night by running quadrupedally across branches,[15] leaping from tree to tree without pausing.[4] They have been seen on the ground and as high as 10 m (33 ft), but they are typically seen running along branches at a height of 3 to 4 m (9.8 to 13.1 ft).[1] Fork-marked lemurs emerge at twilight and call numerous times before going off to forage.[17] Their eye shine creates a unique pattern among lemurs because they tend to bob their heads up and down and from side to side.[4]

Fork-marked lemurs are territorial, with territory size dependent upon food availability. Territory overlap is minimal between males, and the same pattern is seen in females, though males and females may overlap their territories.[26] In areas where territory overlap occurs ("meeting areas"), several neighbors may gather and vocalize together without aggression.[1][27] Unlike other lemurs, fork-marked lemurs do not scent-mark, and instead use vocalizations during territorial confrontations.[28] Fork-marked lemur are considered very vocal animals, a have a complex range of calls.[4] On average, males make approximately 30 loud calls per hour,[1][25] and they are most vocal at dusk and dawn. Their high-pitched, whistling calls help researchers identify them in the field.[4] In addition to their stress call and fighting call, they also emit a Hon call (contact call between male-female pairs), Ki and Kiu calls (more excited contact calls that identify the caller), and a Kea call (a loud call shared between males in adjacent territories). Females also make a "Bleating" call when they have infants.[29]

Males and females are often seen sleeping and foraging together as monogamous pairs, although polygamy and solitary behavior has also been observed.[30] During social grooming, the male allomarks females using a scent gland on the throat.[31] While feeding, females appear to be dominant, gaining first access to food.[32]

Fork-marked lemurs mate in June and have one infant per season, usually in November or December,[1] which are initially parked in tree holes while the mother forages. When mature enough, the infant will cling to the stomach of the mother, but as it gets older it is transported on the back.[33]

Ecology[edit]

These lemurs have a specialized diet of tree tree gums and sap.[4][34] Their diet consists mainly of gum from trees in the genus Terminalia (known locally as Talinala).[4][35] These trees are often parasitized by beetle larvae that burrow beneath the bark. Fork-marked lemurs either consume the gum as it seeps from cracks in the bark or gouge open the bark with their toothcomb to scoop it up directly with its long tongue. Between March and May, gums compose the majority of the diet.[4][17] They have also been documented eating gums from Commiphora species and Colvillea racemosa, bud exudates from Zanthoxylum tsihanimposa, sap from baobab trees (Adansonia species),[17] nectar from Crateva greveana flowers, and the sugary excretions from bugs belonging to the family Machaerotidae, which feed on trees of the genus Rhopalocarpus.[4][17] Although fork-marked lemurs have widely varied forest habitat, gum and other plant exudates of other species are likely to dominate their diet.[17]

The Madagascar harrier-hawk may prey on fork-marked lemurs by extracting them from their sleeping holes.

To meet their protein requirements and obtain nitrogen, they also hunt small arthropods. In captivity, P. furcifer strongly favored preying mantises and moths of the family Sphingidae while ignoring grasshoppers, larva of the moth genus Coeloptera, and small reptiles. Hunting usually occurs later at night, following gum collection, and typically happens in the canopy or on tree trunks. Insects are captured by rapidly grasping them with the hands, a stereotypic behavior seen in other members of its family, as well as galagos.[36]

Other nocturnal lemurs are sympatric with fork-marked lemurs, and in western Madagascar, interspecific competition is reduced by restricting activity to specific levels of the canopy, such as using only the highest sleeping sites at least 8 m (26 ft) above the ground. Competition with other cheirogaleids, such as the gray mouse lemur (Microcebus murinus) and Coquerel's giant mouse lemur (Mirza coquereli), is most intense for Terminalia gum during the dry season, but fork-marked lemurs always drive them off.[24]

Fork-marked lemurs are thought to be preyed upon by large owls, such as the Madagascar owl (Asio madagascariensis) and snakes like the Malagasy tree boa (Sanzinia madagascariensis).[25] In one case, a family of fork-marked lemurs exhibited mobbing behavior when they encountered a Malagasy tree boa.[37] Diurnal raptors, such as the Madagascar buzzard (Buteo brachypterus) and Madagascar cuckoo-hawk (Aviceda madagascariensis) hunt these lemurs at dusk,[25][37] and the hunting behavior of the Madagascar harrier-hawk (Polyboroides radiatus) suggests it might extract them from their sleeping holes. The fossa (Cryptoprocta ferox) has also been seen attacking fork-marked lemurs, and remains have been found in their scat.[37]

Conservation[edit]

In 2012, the International Union for Conservation of Nature (IUCN) listed P. parienti, P. electromontis, and P. pallescens as endangered,[38][39][40] and P. furcifer as vulnerable.[41] Prior to this assessment, it was assumed that their population numbers were in decline due to habitat destruction for the creation of pasture and agriculture. Measures of its population density vary widely, from 50 to 550 individuals per square kilometer, but these numbers are thought to reflect only small, gum-rich areas, and therefore only small, clustered populations with an overall low population density.[1]

As with all lemurs, fork-marked lemurs were first protected in 1969 when they were listed as "Class A" of the African Convention on the Conservation of Nature and Natural Resources. This prohibited hunting and capture without authorization, which would only be given for scientific purposes or the national interest. They were also protected under CITES Appendix I as of 1973. This strictly regulates their trade and forbids commercial trade. Although enforcement is patchy, they are also protected under Malagasy law.[1]

References[edit]

  1. ^ a b c d e f g h i Harcourt 1990, pp. 67–69.
  2. ^ Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. p. 114. OCLC 62265494. ISBN 0-801-88221-4. 
  3. ^ Mittermeier et al. 2010, p. 215.
  4. ^ a b c d e f g h i j k l m n o p q r s t u Mittermeier et al. 2010, pp. 211–212.
  5. ^ Mittermeier et al. 2010, p. 160.
  6. ^ a b Tattersall 1982, p. 131.
  7. ^ Groves & Tattersall 1991, p. 39.
  8. ^ a b c d Groves 2001, p. 71.
  9. ^ a b "New species of lemur discovered in Madagascar". BBC News. 13 Dec 2010. 
  10. ^ "New lemur: big feet, long tongue and the size of squirrel" (Press release). Conservation International. 13 December 2010. Retrieved 5 March 2011. 
  11. ^ a b c Dunkel, Zijlstra & Groves 2012, pp. 66–67.
  12. ^ a b c d e Tattersall 1982, p. 132.
  13. ^ Mittermeier et al. 2010, pp. 218, 226, & 228.
  14. ^ Tattersall 1982, pp. 131–132.
  15. ^ a b c d e f g h i j Fleagle 2013, p. 63.
  16. ^ Charles-Dominique & Petter 1980, p. 84.
  17. ^ a b c d e f g h i j Charles-Dominique & Petter 1980, p. 78.
  18. ^ Szalay & Seligsohn 1977, pp. 77–78, & 80.
  19. ^ a b c Swindler 2002, p. 73.
  20. ^ Mittermeier et al. 2010, pp. 216–217.
  21. ^ Mittermeier et al. 2010, pp. 228–229.
  22. ^ Mittermeier et al. 2010, pp. 226–227.
  23. ^ Mittermeier et al. 2010, pp. 218–223.
  24. ^ a b Schülke 2003, p. 1318.
  25. ^ a b c d Charles-Dominique & Petter 1980, p. 81.
  26. ^ Charles-Dominique & Petter 1980, p. 88.
  27. ^ Charles-Dominique & Petter 1980, pp. 88–90.
  28. ^ Charles-Dominique & Petter 1980, pp. 84–85.
  29. ^ Charles-Dominique & Petter 1980, pp. 81–83.
  30. ^ Charles-Dominique & Petter 1980, pp. 86 & 93.
  31. ^ Charles-Dominique & Petter 1980, pp. 83–84, 86.
  32. ^ Charles-Dominique & Petter 1980, pp. 85–86.
  33. ^ Klopfer & Boskoff 1979, pp. 136–137.
  34. ^ Charles-Dominique & Petter 1980, p. 93.
  35. ^ Charles-Dominique & Petter 1980, p. 77.
  36. ^ Charles-Dominique & Petter 1980, p. 80.
  37. ^ a b c Schülke 2003, p. 1319.
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  40. ^ Andriaholinirina, N., Baden, A., Blanco, M., Chikhi, L., Cooke, A., Davies, N., Dolch, R., Donati, G., Ganzhorn, J., Golden, C., Groeneveld, L.F., Hapke, A., Irwin, M., Johnson, S., Kappeler, P., King, T., Lewis, R., Louis, E.E., Markolf, M., Mass, V., Mittermeier, R.A., Nichols, R., Patel, E., Rabarivola, C.J., Raharivololona, B., Rajaobelina, S., Rakotoarisoa, G., Rakotomanga, B., Rakotonanahary, J., Rakotondrainibe, H., Rakotondratsimba, G., Rakotondratsimba, M., Rakotonirina, L., Ralainasolo, F.B., Ralison, J., Ramahaleo, T., Ranaivoarisoa, J.F., Randrianahaleo, S.I., Randrianambinina, B., Randrianarimanana, L., Randrianasolo, H., Randriatahina, G., Rasamimananana, H., Rasolofoharivelo, T., Rasoloharijaona, S., Ratelolahy, F., Ratsimbazafy, J., Ratsimbazafy, N., Razafindraibe, H., Razafindramanana, J., Rowe, N., Salmona, J., Schwitzer, C., Seiler, M., Volampeno, S., Wright, P., Youssouf, J., Zaonarivelo, J. & Zaramody, A. (2012). "Phaner pallescens". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature. Retrieved 12 December 2014. 
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Literature cited[edit]