Chapter Index

Loris tardigradus nycticeboides / Loris lydekkerianus nycticeboides
(taxonomic research for the genus not yet finished; possibly a distinct species)
Slender loris of the Horton Plains, Ceylon Mountain slender loris

Local names: Sri Lanka (for slender lorises in general): Tamil: thevangu, theivangu (meaning "the slender-bodied one", a term also used for emaciated persons), kadu-papa, kada papa (= "baby of the forest"); Telugu: arawe-papa, devanga-pilli; Sinhalese: unahapuluva (older authors record variations such as unahaputuwa, udahapuluwa, hunu pupuluwa or kalu-unhapuluwa), kalu-unahapuluva, Nama thevangu or nama-theivangu (because of a mark on its forehead resembling the religious symbol namam worn by the worshippers of the Hindu god Vishnu)

Review by H. Schulze, A. Nekaris and C. Groves

Reconstruction of the L. t. nycticeboides type, based on the skin and description of Osman Hill, 1942 and 1953.
No figures of live animals of this form seem to be available.

A mountain form with shorter limbs than in the other slender loris forms and an exceptionally long, soft, thick fur (hair length dorsally up to 25 mm, ventrally up to 30 mm) which completely covers the ears and makes the animal superficially resemble a small slow loris. Ears, hands (except distal phalanges) and feet covered with short fur. Pelage more similar to tardigradus than to grandis, but not reddish: earthy-brown (much lighter than in grandis), no white frosting. Limbs paler than back. Ventral colour ochraceous to buff with grey hair bases (throat hairs without grey bases). Dark, almost blackish circumocular patches, preauricular hair tipped with white. Cutaneous pigmentation: ear rims slightly, eyelid margins deeply pigmented; elsewhere pink to slightly dusky (Osman Hill 1942, 1953)

L. t. nycticeboides is adapted to a climate with frequent abrupt changes of temperature and temperatures sometimes falling to -40C (see below: habitat). In the lowland forms of Loris which are adapted to temperatures above 15 0C, tolerance to cold is relatively low, in nordicus, for instance, at 10-120C environmental temperature a decrease of rectal temperature of more than 50C was measured in spite of an increase of basal metabolic rate and food consumption (Müller et al., 1985). Even the highland slender loris (grandis) inhabits areas where temperature probably hardly falls below 100C (estimated *1) and is clearly less adapted to cold than nycticeboides, with shorter hair and sparsely clothed ears.

*1 L. t. grandis: temperature values estimated for the average altitude of habitat, based on temperature of tardigradus lowland habitat and an average decrease of temperature of 0.50C  with every 100 m altitude

Type locality
Horton Plains, Central Province. 1937, estate of Mr. Tutein-Nolthenius near the Horton Plains “at a height between 5,000 ft. and 6,000 ft” (Nicholls 1939); holotype in the BMNH labelled: Below Horton Plains, 060 48I N, 800 48I E, 6000 ft., May 1938; paratype labelled: Horton Plains, 060 48I N, 800 48I E, 7000 ft. (Jenkins 1987). Animals died after several years in captivity, labelled years after capture and probably not by the collector, data might be inexact.

Distribution area
Endemic to Sri Lankan montane rain and mist forest above 1500 m. The size of remaining possible habitat is about 40 000 hectare (400 km2) in several isolated areas (Werner 1984); nycticeboides has only been found in one of these areas, on the Horton Plains.

 Distribution map

 Localities where the form has been found

Apparently very rare. Known from only two animals found in 1937 by Mr. A. C. Tutein-Nolthenius on the Horton Plains, central Ceylon. “That the animal is rare in that locality is evidenced by the fact that Mr. Tutein-Nolthenius had been on the look out for it for the previous twenty years without success. ... (Osman Hill, 1942). The animals and two offspring died in captivity. Since then, there was only one unconfirmed report of their occurrence based on information of rangers (Dmoch, pers. comm.). During a survey in 2001, rangers and researchers who had worked in the park for years said they had never seen or heard any evidence of lorises in the area (Nekaris, 2001). Wildlife veterinarian Dr. Vijitha Perera later also did not see any lorises there. In 2002, the form was rediscovered during a survey on the Horton Plains by Anna Nekaris who managed to see one and an eyeshine probably belonging to another one (Nekaris, Jayewardene 2003).

Montane evergreen rain and mist forest with Calophyllum walkeri WICHT and other typical plant species, annual rainfall 2000 to 5000 mm; a limited seasonality is observed, without distinct dry period, but the ecosystem sometimes suffers from drought (Werner, 1984). Average temperature: 15.40C, minimum temperature: -40C (Werner 1984; Takahashi and Arakawa 1981; Eisenberg and Lockhart 1972).

Habitat of L. t. nycticeboides. Left: mist over the Horton Plains. Right: pygmy forest. Photos: A. Nekaris


Threat and conservation needs
IUCN red data list 2003: EN A1c. During the IPS meeting in August 2002, nycticeboides was considered for inclusion on the list of twenty five most endangered primates, but finally wasn´t because of insufficient data.
Some facts by A. Nekaris, which should justify listing this form as critically endangered in the future:

-  extent of occurrence estimated to be less than 100 km2
-  the habitat is severely fragmented,
-  the existence of the taxa is only reported at a single location
-  the area of occupancy available for the taxa is continually declining (IUCN, 2002).
The habitat to which this rare form is endemic needs protection: according to Wikramanayake and Gunatilleke (2001), the known high numbers of endemic plant and animal species in the Sri Lankan montane rain and mist forest are the tip of the iceberg, with increasing numbers of species discovered on surveys, and this type of forest can be considered a super-hotspot within the endemism hotspot of global importance recognized by Myers et al. (2000). The forests are important for the whole island because most of the large rivers with water throughout the year have their source here; the trees catch humidity from the mist („fog-stripping"), the water is then retained as in a sponge and released as clear springs even during drought periods. Deforestation leads to drought in the lowland, climatic change and and erosion on the mountains (Werner, 1984; Wikramanayake and Gunatilleke, 2001).
Montane rain and mist forests once probably covered the entire highland of Sri Lanka above 1400 - 1600 m. In the past 200 years, however, most of these forests have been cleared to establish tea and other plantations, pastures or to plant eucalyptus and other alien tree species (Werner 1984; Wikramanayake and Gunatilleke 2001, quoting Ashton et al. 1997). At higher altitudes, on the Horton Plains and elsewhere, the forest have partly been replaced by „wet patanas", almost treeless grassland which, according to Werner (1984) is the result of habitat destruction, kept open by frequent fires, bad soil, overgrazing, dense grass cover and climatic influences which prevent young trees outside the protecting forest from growing. Chambers (1980) reported severe fires on the patanas caused by visitors, destroying shrubs and trees, only Rhododendron arboreum bushes survive.

Patanas: tussock grassland on the Horton Plains replacing the forest,
thought to be the result of early agriculture. Photo: Colin Groves.

After human impact, secondary forest may persist for a long time; often a part of the undergrowth of such secondary forest is dense pygmy bamboo which, after flowering and drying, causes danger of fires to which the forests are not adapted (Werner, 1984). The remaining patches of rain and mist forest are also threatened by illegal logging, collection of fuelwood and large scale illicit gemming. Cultivation of cardamom replacing the natural undergrowth in some areas prevents regeneration of the forest (Werner 1984), and the forests especially in the Horton Plains National Park are experiencing diebacks; investigations are under way to determine the causes (Wikramanayake and Gunatilleke 2001). Highland animal species are threatened by habitat fragmentation (Werner, 1984).

The ecoregion has five protected areas that cover less than 500 km2; none have good protection measures or conservation plans in place (Wikramanayake and Gunatilleke 2001).



Chambers, M. R., 1980: Horton Plains - to burn or not to burn. Loris - The journal of the Wildlife and Nature Protection Society of Ceylon 15 (3): 181-183.

Eisenberg, J. F.; Lockhart, M., 1972: An ecological reconnaissance of Wilpattu National Park, Ceylon. Smithsonian Contributions to Zoology 101: 1 - 119. Smithsonian Press, Washington.

Mani, M. S., 1974: Ecology and biogeography in India. Dr. W. Junk Publishers, The Hague.

Müller, E. F.; Nieschalk, U.; Meier, B., 1985: Thermoregulation in the slender loris (Loris tardigradus). Folia Primatologica 44: 216-226.

Nekaris, K. A. I., 2001: Final Report: Preliminary Survey and Pilot Study of the Slender Loris (Loris tardigradus) in Sri Lanka. Sent to several institutions, publication in Primate Conservation: see Nekaris, Jayewardene, in press.

Nekaris, K. A. I., 2003: Rediscovery of the Ceylon Mountain Slender Loris in the Horton Plains National Park, Sri Lanka. Asian Primates 8 (3, 4): 1-7.

Nekaris, K. A. I.; Jayewardene, J., in press: Pilot study and conservation status of the slender loris (Loris tardigradus and Loris lydekkerianus) in Sri Lanka. Primate Conservation.

Nicholls, L., 1939: Period of gestation of Loris. Nature (London) 143: 246.

Osman Hill, W. C., 1942: The slender loris of the Horton Plains, Ceylon, Loris tardigradus nycticeboides subsp. nov.. Journal of the Bombay Natural History Society 43: 73-78.

Osman Hill, W. C., 1953: Primates: Comparative anatomy and taxonomy. Vol. I, Strepsirhini. Edinburgh University Press, Edinburgh.

Takahashi, K.; Arakawa, H. (eds.), 1981: Climates of southern and western Asia. Elsevier, Amsterdam.

Werner, W. L., 1984: Die Höhen- und Nebelwälder auf der Insel Ceylon (Sri Lanka). [The montane and mist forests of the island of Ceylon (Sri Lanka)] Tropische und subtropische Pflanzenwelt 46. Steiner, Wiesbaden. (German)

Wikramanayake, E. D.; Gunatilleke, S., 2001: Sri Lanka montane rain forests (IM0155). http://www.worldwildlife.org/wildworld/profiles/terrestrial/im/im0155_full.html. (Series: www.worldwildlife.org, Wild World WWW full report. Seen: 24 Sept. 2002.
Originally published in: Wikramanayake, E.; Dinerstein, E.; Loucks, C. J. et al., 2001: Terrestrial Ecoregions of the Indo-Pacific: A Conservation Assessment. Island Press, Washington, Covelo, CA. Sponsored by World Wildlife Fund. ISBN: 1-55963-923-7.

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Last amendment: 14 October 2004

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