Craseonycteris thonglongyai
bumblebee bat
(Also: hog-nosed bat)

Ban Sai Yoke, Kanchanaburi Province, Southwestern Thailand

Craseonycteris thonglongyai dwells far from the entrance, deep in the most remote, small limestone caves (Nowak and Paradiso, 1983). These caves are located in a previously forested area, which had been completely clearcut in the 1950's and is now dominated by teak plantations (Macdonald, 1984).

The size of a large bumblebee, Craseonycteris thonglongyai may be the world's smallest mammal. Its head and body length ranges from 29 to 33 mm, and its forearm ranges from 22 to 26 mm. One of C. thonglongyai's most distinctive features is its pig-like muzzle, which is swollen around the nostrils and chin. The wide, crescent-shaped nostrils open directly in the face of the nose pad, which is formed by the wide septum. Another distinct trait is C. thonglongyai's lack of a tail, despite the presence of two caudal vertabrae. The upper side of the body is either brown to red or grey. The underside is generally paler, while the wings and interfemoral membrane are dark. Bats of this species have small eyes, which are mainly concealed by fur, and large ears. The tragus is almost one half the length of the ear, narrow at its base and widest at its middle. A glandular swelling at the base of the throat is found in a males, who also has a relatively large penis. A female has a pair of pectoral nipples and a pair of vestigial pubic nipples. The long and wide wings have a tip adapted for hovering. The propatagium is broad, the thumb short with a well-developed claw, and the hindfeet are long and narrow. Craseonycteris thonglongyai has a dental formula of 1/2 1/1 1/2 1/3. Its upper incisors are large, and its lower incisors are tricusped, with the middle cusp dominant (Nowak and Paradiso, 1983). Koopman (1984) describes them as normal insectivorous-type teeth.

The skull is small with an inflated and globose braincase, prominent sagittal crest, slender zygomatic arch and large, flat bullae. It lacks a postorbital process (Nowak and Paradiso, 1983). The premaxillaryi is separate from the surrounding bones. The nasal branch, which is fused posteriorly and lies on the nasals and maxillae, is more developed than the palatal branch. The palatal branch is fused anteriorly and posteriorly, forming a large vacuity (Lawlor, 1979). Its postcranial sketelon varies from other bats in that its second manal digit has a single bony digit. It has a threadlike fibula, a weak pelvis, and extremely fused sacral vertebrae (Koopman, 1984). Craseonycteris thonglongyai also lacks a calcar (Nowak and Paradiso, 1983).

Craseonycteris thonglongyai is a colonial animal, roosting in groups in caves (Macdonald, 1984). However, an individual within a group is solitary. Though close to others in its group, it hangs alone, rather than clustering tightly. It is most active at dusk, at which time it flies around the tops of bamboo clumps and teak trees (Nowak and Paradiso, 1983).

Craseonycteris thonglongyai is an insectivorous bat. It appears to feed at night by gleaning on foliage, taking in the small arthropods that rest on the tops of bushes and trees (Nowak and Paradiso, 1983). Diptera make up approximately 80% of its diet, with Hymenoptera and occasional Psocoptera comprising a much smaller portion (Nabhitbhata, 1982).

Craseonycteris thonglongyai is endangered and rare, a CITES list animal. The total population is estimated at two hundred individuals.

Craseonyteris thonglongyai was only described in 1974 by Hill. It represents an intermediate family between Rhinopomatidae and Emballonuridae. It is the only genus and species in its family.