Bracketing the extremes: courtship behaviour of the smallest- and largest-bodied species in the salamander genus Desmognathus (Plethodontidae: Desmognathinae)

Abstract

With both a ‘manageable’ number of taxa and moderate levels of behavioural diversity, plethodontid salamanders of the North American subfamily Desmognathinae offer exciting opportunities for a phyloethological study of courtship. In moving toward this goal, the present paper reports courtship descriptions for two taxa with very different biologies: the pygmy salamander Desmognathus wrighti and the blackbelly salamander D. quadramaculatus. Despite similarities in behaviour patterns used to accomplish indirect sperm transfer by means of the deposition of spermatophores on the substrate (tail-straddle walk), these two taxa greatly differ in the ways by which males stimulate, or ‘persuade’, females to mate. Male D. wrighti bite and seize their partners in order to provide them with tactile and chemical stimuli. In contrast, male D. quadramaculatus provide these same stimuli, but by head rubbing and snapping. I end with a comparative survey of courtship in the Desmognathinae, and a first attempt to interpret behavioural evolution in the subfamily using a phyloethological analysis.