Skull and Hair Morphology of the 2 Subspecies of Variable Squirrels, Callosciurus finlaysonii (Horsfield, 1823)

Abstract

A morphological study of skull and hair was carried out in attempt to use in identification the two subspecies of variable squirrels found in Khon Kaen University campus, i.e. Callosciurus finlaysonii bocourti (Milne-Edwards, 1867) and C. Finlaysonii boonsongi (Moore and Tate, 1965). Skull samples were simply prepared by boiling and getting rid of soft tissue parts. Hair samples from both subspecies were taken from dorsal, ventral, lateral, and tail areas, and processed for impression and whole mount techniques before examining under light microscope. The two subspecies showed similar characters of skull including short-expanded skull form, short-curved rostrum, well develop postorbital process, long jugal bone, short-broaden palatine, and big tympanic bulla with tiny bulb shape. Hair morphology appeared with elongate imbricated form with smooth margin and irregular arrangement, not only in the same subspecies but also in between subspecies. Serial ladder medulla was prominently observed along the entire shaft in C. Finlaysonii bocourti, whereas appeared only half beginning of the shaft and continued with lattice pattern along the half end shaft in C. Finlaysonii boonsongi. Similar appearance of skull morphology in both subspecies is unable to use in identification. In contrary with hair structure that showed some differences regarding medulla structure that give some indications in identification of the two subspecies.