DEVELOPMENT OF THE LIMB SKELETON OF Bufotes variabilis (ANURA: BUFONIDAE) AND COMPARISON WITH OTHER BUFONIDS

We describe the patterns of the limb chondrogenesis and ossification in Bufotes variabilis (Pallas, 1769) by using both serial sections and cleared-and-stained whole mount specimens. The limb morphologies with whole-mount specimens in B. variabilis are compared with those of Bufo bufo and Bufo calamita, whereas the serial sections are compared with those of Rana temporaria and Salamandrella. Based on examination of cleared-and-stained whole mount specimens of B. variabilis, we found that the first ossified limb elements are the femur and tibiofibula (Stage 37) and followed by the humerus and radioulna (Stage 38). Our results clearly show that there are some significant timing differences among bufonids and observations using serial sections are more detailed than whole-mount specimens because of determination of earlier differentiation of limb elements