Abstract

The microanatomy of the oral discs of the tadpoles of Bufo dhafarensis and Rana ridibunda were described. Tadpoles of stage 49 and 41, respectively were examined and analyzed using scanning electron microscope. In Rana tadpoles, the mouth was ventral and the oral disk opening had the same vertical and horizontal opening size. While in Bufo tadpoles, the mouth was anterio-ventral and the oral disc had its horizontal opening larger than the vertical one. The border of oral disc of tadpoles of B. dhufarensis was surrounded with 22 marginal papillae and 8 submarginal papillae and a dorsal gap was observed. The  oral disc of Bufo had less number of marginal papillae where they were short and had broad smooth ends with no apical parts. On the other hand, the border of  the Rana’s oral disc was surrounded by 50 marginal papillae and 10 submarginal where the dorsal gap was also observed. Both marginal and the submarginal papillae were long, numerous, closely spaced and ending with 3-7 apical parts in each papilla. The labial tooth row formula (LTRF) of the tadpoles of B. dhufrenensis was 2/3, while that of the tadpoles of R. ridibunda pallas was 2(1)/3(1-2). In B. dhufarensis, the labial teeth were keratinized, short ending with 4-7 terminal cusps and arranged as a single row. On the contrary, the labial teeth of R. ridibunda pallas were elongated, closely spaced and numerous. These labial teeth were noticed to be either vertically positioned or curved downwards carrying 3-4 terminal cusps in their free ends. Herein, we described Saudi Arabian Amphibian B. dhufrenensis and R. ridibunda pallas by utilizing scanning electron micrographs. In the present study, we described deformities in the oral disc of B. dhufrenensis and R. ridibunda pallas tadpoles in their natural conditions.

Key words: Oral disc, tadpoles, Rana ridibunda, Bufo dhufarensis, labial tooth row formula, deformities.