Male and Female Cloacal Anatomy of the Fischer’s Clawed Salamander, Onychodactylus fischeri (Caudata, Hynobiidae)

Abstract

The cloaca of salamanders is a complex organ with exocrine glands involved in the production of sex pheromones, spermatophores, and storage of sperm. Since the cloaca provides reproductive functions, its signs are important for phylogenetic analysis in the evolutionary biology of tailed amphibians. For clarification of intrafamilial variation of cloacal characteristics in hynobiids, we studied the anatomy of male and female cloacae of Onychodactylus fischeri via histological, histochemical, and 3D-reconstruction methods. Males and females had ciliated cloacal linings and with sexual dimorphism in cloacal conformation and cloacal glands. As in other males and females of hynobiids, females of O. fischeri possessed only ventral glands, secreting neutral glycoproteins. In contrast, males of this species had three types of the cloacal glands. Glands «B» were like ventral glands of females and other hynobiids, while glands «A» and «C» had different histochemical and morphological characteristics. As our results are generally consistent with the data for the related species O. japonicus, these characteristics of the male and female cloacal anatomy may be common to all species of the genus Onychodactylus. The presence of three types of unique cloacal glands in males distinguishes Onychodactylus from all other hynobiids and salamanders.