Cloacal Anatomy of Female Salamanders of the Plethodontid Subfamily Desmognathinae (Amphibia: Urodela)

Abstract

The cloacae of females from the 11 currently recognized species in the salamander genus Desmognathus and from the monotypic genera Leurognathus and Phaeognathus were examined by light microscopy after preparation of microscope slides by standard techniques using paraffin-embedded tissues. Analyses included three-dimensional reconstructions of serial sections. All species possess spermathecae consisting of acini for sperm storage that evaginate from a common tube that passes into the cloaca. In P. hubrichti, the common tube passes horizontally into a cloacal chamber recess medial to the distal ends of the oviducts, and the spermathecae are anterior to the common tube. In the other species, no recess exists, the common tube passes ventrally into the posterior cloacal tube or anterior cloacal chamber, and the spermathecae are posterior to the common tube. Rudimentary cloacal glands called dorsal glands and ventral glands, which are symplesiomorphic characters for plethodontids, occur in some desmognathines. These glands vary from numerous in P. hubrichti and in large aquatic species (D. brimleyorum, D. monticola, and D. welteri) to absent in small terrestrial species (D. aeneus, D. wrighti). An anterior closed portion of the cloaca, the cloacal tube, is absent in D. quadramaculatus and L. marmoratus. Atavism and selection pressures for paedomorphosis, terrestriality, and/or miniaturization may be involved in cloacal variation among female desmognathines.