Dentigerous bones and dentition in the hemiramphid fish Dermogenys pusillus (Atheriniformes, Teleostei)

Abstract

Structure and arrangement of the teeth were studied in the hemiramphid Dermogenys pusillus, using scanning electron microscopy as well as cleared and stained specimens. The teeth of the jaws are small, monocuspid, and tilted towards the esophagus. They are arranged along the lateral edges of the premaxillas and dentaries. Each premaxilla bears additional teeth on an osseous bar extending from rostro-lateral to medio-lingual. The dentition of both dentaries curves slightly within the cavity of the mouth and gently tapers off laterorostrad just beyond the tip of the upper jaw. The part of the lower jaw, which typically protrudes beyond the upper jaw, is without teeth. One dorsal and two lateral tooth-bearing bony plates (tooth plates) are found in the pharyngeal region. Their teeth are largely irregular in arrangement. The teeth on the two lateral plates are small and monocuspid, whereas the dorsal and the ventral tooth plate possess additional strong bi- and tricuspid teeth. The teeth of the jaws and of the pharyngeal region obviously have a bony pedicel ("attachment bone") which is asymmetric in all teeth. An elastic suture connects the cone of dentine with the bony pedicel. The special construction of the teeth and their arrangement on the various dentigerous bones will be discussed with respect to their function in catching prey.