Husbandry Manual for Asian Lorisines (Nycticebus & Loris ssp.)

In this manual, we decided to use the old taxonomic names because they are better known.
 
 

Figure 1: Genus Nycticebus (continued on page 2)

Loris Husbandry Manual

Figure 1: Genus Nycticebus (continued)

Mitochondrial DNA polymorphism analyses suggest that the two species of the genus Nycticebus commenced divergence 2.7 million years ago (Zhang et al., 1993). A third form has been referred to as Nycticebus intermedius. Even though they are morphologically dissimilar, the genetic differences between Nycticebus pygmaeus and N. intermedius are not sufficient for separate species classification (Zhang et al., 1993).

Lorises have very large eyes, which are directed forward. Their tightly clinging hands and feet have human-like nails. The nail on the second digit of the foot is elongated and rolled up to form a grooming claw. They can maintain a grip while remaining completely immobile for long periods due to a specialized network of blood vessels in the limbs. Like other prosimians, lorises have closely
 
 

Figure 2: Genus Loris

Figure 3: Genus Arctocebus

In pottos, the vertebral spines in the nuchal region protrude through the skin; they are used for defense (Charles-Dominique, 1977). In Pseudopotto (only skeletal material known) the vertebral spines are shorter (Schwartz, 1996).

Figure 6: From left to right: hand of Loris tardigradus; hand of Nycticebus coucang; hand of Arctocebus calabarensis; hand of Perodicticus potto.
 
 

Figure 7: Some structures in the mouth of Loris tardigradus nordicus. Tooth comb (ventral side, upper jaw stippled grey), tongue with sublingua (sublingua tips are used for cleaning the tooth comb), and entrance to the vomeronasal organ (supplementory olfactory organ).

Loris Husbandry Manual
 
 

Figure 8: Some skin glands found in prosimian primates. Grey text: Glands of Malagasy lemurs. Black text: Glands found in lorises or pottos. Based on Schilling (1979), Manley (1976), Alterman (1995), Rasmussen and Nekaris (1998), Montagna et al. (1959, 1966), and other sources.

Slow Loris

Slow lorises are robust, compact animals with short and dense woolly fur. They have a very round head and thick muzzle with a rounded snout. Adult slow lorises average about 1,400 grams. Some subspecies can reach up to 2,000 grams, while others weigh less than 900 grams. Coat color ranges from silvery to reddish or dark brown and it may change seasonally. Slow lorises have a dark dorsal stripe that runs from the rump to the top of the head, and their eye rings have a triangular shape. Both slow and pygmy lorises have vestigial tails. According to Groves (1971), there are four valid subspecies (Table 2). In Groves (1998), two former subspecies (N. c. bengalensis, N. c. javanicus) are regarded as distinct species. Subspecies identifications are difficult and somewhat unreliable for both the slow and slender lorises. There are overlaps in identifying physical characteristics and problems in identification of geographical origins. As a result of this confusion, there are likely to be hybrids in the captive population. Most slow lorises currently in captivity are classified as either N. c. bengalensis (the larger, silver variety), or N. c. coucang (the smaller, brown type). Further genetic research is needed to establish a basis for each subspecies and to identify individual captive specimens.

Pygmy Loris

Captive pygmy loris adults average 450 grams, although obese specimens can weigh as much as 600 grams. This species is about 1/3 to 1/2 the size of N. coucang. They also have larger ears and differences in dentition. The fur is fine and wavy and brownish orange in color, and the markings are similar to the slow loris. Their fur often develops a silvery frost during the winter months. Six pygmy lorises that were weighed at an animal market in Vietnam averaged 353 grams (Tan, 1994).

The distribution and morphological differences between N. pygmaeus and N. intermedius are not well defined. Alterman and Freed (1997), have found a different form of Nycticebus that occurs in Laos, but more data are needed for classification.

Table 3: Forms of the pygmy loris proposed.
 

Loris Husbandry Manual

Slender Loris

Slender lorises are distinguished from the slow lorises by their slender build and thin, elongated limbs. The average weight is approximately 210 grams. The muzzle is more pointed than in the slow and pygmy lorises, and the tail is vestigial or absent. The dorsal stripe is faint or absent in some subspecies. Six subspecies of the slender loris are recognized (Hill, 1953; Napier and Napier, 1967; Petter and Petter-Rousseaux, 1979). Groves (1998) questions this and states, for instance, that L. t. tardigradus is morphologically distinct from all other forms. Further taxonomic research is necessary.

Table 4: Subspecies of the slender loris (Petter and Petter-Rousseux, 1979; Napier and Napier, 1967; Hill, 1933 and 1953).
 

Only L. t. tardigradus, L. t. nordicus, and L. t. lydekkerianus have been reported in North American collections. Some smaller reddish or brownish slender lorises have not been positively identified. These may be L. t. tardigradus, L. t. malabaricus, naturally occurring intermediate forms between L. t. tardigradus and L. t. grandis or captive-bred mixtures of these forms.
 
 

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Management of Lorises in Captivity. A Husbandry Manual for Asian Lorisines (Nycticebus & Loris ssp.) Edited by: Helena Fitch-Snyder and Helga Schulze. Compiler: Lena C. Larsen

Last amendment: 21 January 2003