Cloacal anatomy of the palmate newt, Triturus helveticus (Amphibia, Salamandridae)

Abstract

The cloacal anatomy of the palmate newt, Triturus helveticus, was studied in both sexes using light and scanning electron microscopes. The female cloaca is characterized by the occurrence of rugae and folds. Two folds are especially prominent in the region where the spermathecal tubules open into the cloaca. In addition to sperm storage structures, vent glands are obvious in the connective tissue around the cloacal orifice. Their pores occur externally to the cloacal borders, thus suggesting that these glands are a possible source of mating pheromones. Typical features of the male cloaca are: a ciliated epithelium; a cloacal tube dorsal and separate from the anterior cloacal chamber; a broad pseudopenis and wide lateral recesses in the cloacal chamber. Four main types of cloacal glands are recognized in males (dorsal, pelvic, Kingsbury's, and ventral gland). Quite unusual is the occurrence of two distinct types of dorsal glands, possibly related to the production of different pheromonal substances. These glands in the male, together with the occurrence of vent glands in the female, are proposed as cloacal specializations for the production of unequivocal species-specific sex attractants.