Loris lydekkerianus, Cabrera, 1908
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publication ID |
https://doi.org/ 10.5281/zenodo.6632647 |
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DOI |
https://doi.org/10.5281/zenodo.6632675 |
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persistent identifier |
https://treatment.plazi.org/id/039C9423-FFFE-0871-3168-D49E5251F8A8 |
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treatment provided by |
Carolina |
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scientific name |
Loris lydekkerianus |
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Gray Slender Loris
Loris lydekkerianus View in CoL
French: Loris de Lydekker / German: Grauer Schlanklori / Spanish: Loris esbelto gris
Other common names: Dry Zone/Northern/Northern Ceylon Slender Loris (nordicus), Highland Slender Loris (grandis), Malabar Slender Loris (malabaricus), Mysore Slender Loris (lydekkerianus)
Taxonomy. Loris lydekkerianus Cabrera, 1908 View in CoL ,
India, Madras.
C. P. Groves in his book Primate Taxonomy in 2001 considered L. [. grandis and L. I. nordicus synonymous, but this is difficult to resolve. They are similar cranially, but their pelage and especially the muzzle and face are remarkably distinct. They are recognized as distinct subspecies here. K. Kar Gupta in 2007 reportedly studied L.. malabaricus, but the individuals from Mundanthurai Tiger Reserve, India, have the appearance of L. L lydekkerianus . Four subspecies are recognized here, but there is much overlap in their physical characteristics. Ongoing confusion over their taxonomy requires future research.
Subspecies and Distribution.
L. l. nordicus Hill, 1933 — NC & E Sri Lanka throughout the lowland Dry Zone;it is uncertain if its distribution extends to SE Sri Lanka. View Figure
Descriptive notes. Head—body 21-26 cm,tail vestigial; weight varies among the subspecies. The Gray Slender Loris is similar to the Red Slender Loris (L. tardigradus) but larger, with a less pointed muzzle and more regional variation. Pelage is fairly short, and a dorsal stripe is sometimes present. Two subspecies are recognized in India. The “Mysore Slender Loris” (L. Ll. lydekkerianus) is a large subspecies, with head—body lengths of 20.3-22 cm and adult weight of ¢.294 g (males) and ¢.259 g (females). It is grayish-buff above, often with white frosting, and whitish-buff below with or without white frosting. Eye patches are gray to brown, pre-auricular hairs are white, and ears are yellowish brown. W. C. O. Hill in his review of 1953 reported specimens with black ears, but these have never been seen in the wild or found in subsequent museum specimens. Variation occurs across its very large range, especially in body size, and more Indian subspecies or even species are suspected. The “Malabar Slender Loris” (L. I. malabaricus), despite being in the Gray Slender Loris species, bears a striking resemblance to the Red Slender Loris, perhaps because it shares similar forest habitat. Pelage is red-brown with or without white frosting on the dorsum and head, and the dorsal stripe is usually absent or indistinct. Head-body length is 18:3-19.8 cm, and adult weight is 180 g. Two subspecies of the Gray Slender Loris are found in Sri Lanka. The “Northern Ceylon Slender Loris” (L. [. nordicus) has a dense woolly pelage and is gray, gray-brown, or buff-brown dorsally and white or light buff ventrally. The throat and median line of the belly are usually creamy buff throughout with no gray hair bases, although medium to pale gray hair bases may intergrade with hairs on the outer part of the creamy underside. The head and dorsum can either have frosting or not, and there is usually a dark dorsal stripe that meets a dark crown. Circumocular patches are dark gray, gray, or gray-brown, and preauricular hairs are either white or light gray extending to white cheeks, making the facial mask more outstanding than in the Red Slender Loris. Ears are large compared with the eyes and are yellow or yellow with dusky ear rims. The Northern Ceylon Slender Loris has a head-body length of 21.5-23.8 cm (males 22-7 cm, females 21-7 cm). Male weight (228-285 g) is slightly higher than that of females (238-287 g). The “Highland Slender Loris” (L. I. grandis) was described by Hill and W. Phillips in 1932. The plates of the living animals in the original description bear a striking resemblance to the Red Slender Loris but no resemblance to living Northern Ceylon Slender Lorises—therefore the separate taxon recognized here. The type was found in Gammaduwa at 675 m above sea level. This medium-size slender loris has a head-body length of 20.9-25.6 cm, and a weight of ¢.220 g. Pelage of grandis makes it distinct from other subspecies. It is dark gray or gray-brown dorsally and sometimes a rusty-brown on the lumbar region. It is ventrally white or light buff on distal ends of the hairs, with the basal one-half being black, unlike the subspecies nor dicus where ventral hairs have pale hair bases fading to pure white at the midline. The throat of grandis is pure white, and it has an indistinct dark dorsal stripe that usually is frosted. Circumocular patches are black, brown, or red-brown. The white interocular stripe bifurcates above circumocular patches. Cheeks and preauricular hairs are mainly white, similar to nordicus. The coat of grandis is thicker than that of tardigradus ; it is sometimes so thick as to resemble a subspecies of the Red Slender Loris (the “Horton Plains Slender Loris,” L. t. nycticeboides). The heart-shaped face of grandis has a very long muzzle, which also distinguishes it from other subspecies. As in all the Sri Lankan lorises, infants of grandis are reddish and assume the adult coloration at 8-9 months of age. It would be difficult to tell grandis from nordicus by observing only an infant.
Habitat. The Gray Slender Loris occurs in tropical primary and some secondary rainforest, dry semi-deciduous forest, shrub, evergreen, swamp, acacia, bamboo, edge, and montane cloud forest to 2000 m above sea level. It occupies the understory in dry forests and the canopy in wetter areas. It can persist in home gardens, tea plantations, and hotel grounds, where it probably lives mainly on insects. Gray Slender Lorises move at heights of 2-5 m, depending on their habitat. They move in a serpentine fashion, from ground to canopy, and also cross gaps of open ground, including roads and paddy fields.
Food and Feeding. Faunivorous, consuming mainly invertebrates (including ants and mollusks), along with bird eggs, nestlings, geckos, birds, tree frogs, small mammals, unripened fruits, young leaves, and gum. In the only detailed long-term study of the species’ diet, 96% ofall feeding events focused on animal prey, the majority of which were ants and termites. In addition to spiders, mollusks, and lizards, other key insect orders in the diet include: Lepidoptera, Coleoptera, Orthoptera, Odonata, Hemiptera, and Diptera. Lorises are able to eat insects with high levels of secondary compounds, accompanied by pre-ingestive urine washing, or slobbering and urine washing during ingestion. Gray Slender Lorises are terminal branch specialists that catch their prey visually with one or two hands, and they use acrobatic postures in the more dangerous and swaying branches. Lorises infrequently feed on gums and legume pods, but they can make holes in bark through active gouging. Observations of the Sri Lankan forms are in accordance with those of longer-term studies in India. The Northern Ceylon Slender Loris was observed to eat only insect or animal prey, including lizards and snails. They nearly always detect their prey with their eyes and engage in acrobatic suspensory postures to catch their prey items. They grasp the prey with one or two hands, and prey items are rarely caught and eaten directly with the mouth. Northern Ceylon Slender Lorises do not appear to eat gum or drink water, and the only non-insect item they appear to eat is nectar from a flowering Cassia roxburghii ( Fabaceae ). In captivity, the Highland Slender Loris feeds on tree frogs, geckos, and large insects.
Breeding. Copulation patterns are similar among the two species of Loris. Mating can occur after play wrestling, but it most often commences after many males have pursued a female. Usually, males move into an area a few days before a female enters full estrus and start to follow her and try to groom her. These interactions can result in violent fights between males. During the pursuit, the males utter “krik” calls at irregular intervals and try to inspect the female’s genitals. The female may give defensive threats, but when she is ready to be mounted, she signals with a suspensory posture. Copulations take place with the male clinging to the female, who is suspended quadrupedally. A female supports herself by all four limbs orjust her hindlimbs. A single copulation may last 2-16 minutes and is ended with the female giving low-intensity threat gestures toward the male. Sometimes the male produces a liquid that forms a vaginal plug. Both sexeslick their genitals after copulation. Gray Slender Lorises give birth to singletons or twins after a gestation of 157-162 days. Births occur throughout the year. A female gives birth in a sitting or a hanging posture. Newborns have partially opened eyes. After birth, the mother may defend the infants against conspecifics if they become overly curious, but often she will allow an adult male from her social group to groom her and her offspring. The newborn clings to the mother’s belly for the first few weeks oflife. Weaning occurs after 148 days. The infantis carried less when it is 2-3 months old, and it may be parked while the mother goes off to feed.
Activity patterns. The Gray Slender Loris is nocturnal and arboreal, and it moves quadrupedally in trees. Although it can move slowly when threatened,it is generally silent and swift. It prefers to move on the top of branches. Gaps between branches are crossed by using horizontal bridging, whereby hindlimbs hold on to a substrate while forelimbs grab for the desired branch. Three limbs are usually holding a support branch when moving in a quadrupedal fashion. The Gray Slender Loris is capable of rapidly scaling a large tree trunk or scampering along other large substrates, although it prefers small supports that it can clasp firmly in its hands. It crosses roads and agricultural fields when necessary.
Movements, Home range and Social organization. Social organization of the Gray Slender Loris has been described as dispersed multimale—multifemale, but with unimale—unifemale subunits. Home-range sizes of the Mysore Slender Loris are c.3-6 ha for adult males and 1-6 ha for adult females. Home-range sizes of the Malabar Slender Loris are 1-2-14 ha for adult males and 3-15-3 ha for adult females; roving males can have home ranges as large as 117 ha. Home ranges of adult males overlap one or more females, but home ranges of adult females are exclusive, except for their offspring. Social interactions are common; the Mysore Slender Loris, in particular, is among the most social of the lorises, with up to 38% ofits activity spent in association with other individuals. The Gray Slender Loris, in general, forages at night, alone or in groups of two or three, sometimes larger. An individual usually sleeps with one to four conspecifics and chooses one of three or four sleeping sites night after night. Sleeping site fidelity for resident individuals seems to be high, whereas roving males or dispersing individuals often change their sleeping sites and sleep alone. Sleeping sites are vine tangles, forks, or dense thickets. Grooming is common, and males frequently groom infants when they are parked or on the mother’s belly. Peaceful food sharing occurs among members of a group, although it is not active. The Gray Slender Loris engages in social play; adult males and juveniles play-wrestle most often, but older individuals may also participate. A typical wrestling bout includes two individuals facing each other and gripping the head from the back and pulling the head back. They try to gently bite the other’s hands and feet. A whistle is the most common call of the Gray Slender Loris, uttered throughout the night; it may be used as a countercall, a spacing mechanism, or a territorial call. This call is heard in situations of aggressive excitement and is emitted by adults of both sexes. The “chitter” call is heard in defensive situations between conspecifics and is emitted by males and females. The krik call may be uttered in situations where an infant will threaten its mother in response to other group members’ quarrel. The Gray Slender Loris screams when attacked by a predator; and one individual was also heard screaming when electrocuted crossing an open power line.
Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List. The subspecies grandis and nordicus are classified as Endangered, and the nominate subspecies and malabaricus are classified as Near Threatened on The IUCN Red List. The principal threat is loss of habitat. Loris eyes are valued in traditional Asian medicine because of the local belief that they contain certain properties that are effective against ocular complaints. In India, the eye of the loris is also widely used as a love charm in a preparation that is claimed to be helpful in seducing and kidnapping a woman. The Mysore Slender Loris is reported from three protected areas: Sri Venkateswara National Park and Biligiri Rangswamy Temple and Nelapattu wildlife sanctuaries in India. The Malabar Slender Loris is reported in Periyar National Park and a number of wildlife sanctuaries in India, including Aralam, Brahmagiri, Griz zled Giant Squirrel, Idukki, Indira Gandhi, Kalakkad-Mundanthurai, Parambikulam, Peechi-Vazhani, Shendurney, Someswara, Thattakkad, and Wynad. In Sri Lanka, the Northern Ceylon Slender Loris is reported from reserves and sanctuaries of Ampara, Girithale, Mihintale, Polonnaruwa, Ritigala, Sigiriya, and Thangamale; national parks of Angammedilla, Flood Plains, Kaudulla, Maduru Oya, Minneriya, Somawathiya, Wasgamuwa, Wilpattu, and Yala; and forest reserves of Kanthale and Menikdena. The Highland Slender Loris is reported from only three protected areas: Knuckles Mountain Range, Victoria-Randenigala-Rantambe, and Udawatta Kele.
Bibliography. Christie (1992), Devaraj Sarkar et al. (1981), Fitch-Snyder & Schulze (2001), Goonan (1993), Groves (2001), Hill (1933, 1953d), Ilse (1955), Izard & Rassmussen (1985), Kadam & Swayamprabha (1977, 1980), Kar Gupta (2007), Kumara et al. (2006), Meier (1989), Nanda Kumar et al. (2004), Napier & Napier (1967), Nekaris (1997, 2000, 2001, 2002, 2003a, 2003b, 2005, 2006), Nekaris & Bearder (2007), Nekaris & Jayewardene (2003, 2004), Nekaris & Rasmussen (2003), Nekaris & Schulze (2004), Nekaris et al. (2006), Rao (1994), Rhadakrishna (2001), Rhadakrishna & Singh (2002, 2004a, 2004b), Schulze & Meier (1995a), Singh, Kumar et al. (2000), Singh, Lindburg et al. (1999), Swayamprabha & Kadam (1980).
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