PARENT SESSION

THE GIANT TREE SQUIRREL, RATUFA BICOLOR, ONE OR SEVERAL SPECIES? Katherine E. Ferrell and Richard W. Thorington. Smithsonian Institution, Washington, DC, USA.

ABSTRACT- The giant tree squirrel, Ratufa bicolor, as presently understood (Moore and Tate, 1965; Corbet and Hill, 1992; Hoffman et al., 1993), has a geographic range which extends from Nepal to Java and Bali. In the past, several species have been recognized within this range. The northern two subspecies, R. b. gigantea and R. b. hainana, with distinct ear tufts, have been considered specifically distinct from the more southern subspecies, which lack ear tufts. The Isthmus of Kra has also been used as a specific boundary between R. b. phaeopepla and R. b. melanopepla. Similarly, the Strait of Malacca has been used as a geographic boundary between species, separating the Ratufa of the Malaysian peninsula from those of Sumatra; the Strait of Sunda is also a potential boundary between the white-tailed Ratufa b. bicolor of Java and Bali and the browner Ratufa b. palliata of Sumatra. We are examining these hypotheses, using craniometry to determine if differences in external morphology are paralleled by significant differences in cranial measurements and proportions. Canonical Variate Analysis readily discriminates among several of these populations, using distance measurements in a landmark-based truss. The distinctness of populations of Ratufa bicolor on Java, on Sumatra, and on Con Son Island of Vietnam from relevant mainland populations raises the dual questions of how long the populations have been genetically isolated and whether they should be considered distinct species.

KEY WORDS: Ratufa bicolor, craniometry, systematics, southeast asia