Tooth Morphology and Enamel Microstructure of the Lesser Bamboo Rat (Cannomys badius)

Abstract

The lesser bamboo rat is a fossorial rodent monotypic within the genus Cannomys, family Spalacidae. The present study revealed the first detailed information on its dental morphology, particularly the enamel microstructure, as examined by stereoscopic dissection and scanning electron microscopy. The lesser bamboo rat possesses proodont incisors covered with orange-pigmented enamel on the smooth front surface. The molars are mesodont-lophodont. The first upper molars are characterized by a tetralophodont (four lophs) pattern with four roots, whereas the first lower ones are pentalophodont and have three roots. Concerning the enamel microstructure, the incisors are comprised of a relatively thick Portio externa of radial enamel and prismless enamel (PLEX), and the Portio interna, formed by uniserial Hunter-Schreger Bands. Molar enamel microstructure shows a primitive (P)-type schmelzmuster with an occasional appearance of either irregular prism clusters or PLEX. The teeth and enamel of the lesser bamboo rat are somewhat different from those of other spalacid relatives. Although retaining a primitive state, they show some structural adaptations to feeding and tooth-digging lifestyles.