Histology of mental and caudal courtship glands in three genera of plethodontid salamanders (Amphibia: Plethodontidae)

Abstract

Salamanders in the family Plethodontidae exhibit a unique tail‐straddle walk during courtship that can include the use of sexually dimorphic mental and caudal courtship glands. This study presents novel histological and fine structure data on mental glands and caudal courtship glands in Plethodon mississippi, Desmognathus conanti and Eurycea quadridigitata using both light microscopy and scanning electron microscopy. This study represents the first use of scanning electron microscopy to observe these glands. Both mental and caudal courtship glands were observed to vary seasonally in gland diameter and histology according to the breeding season of each species. Morphological variation was observed across the three species studied in both clustering and relative size of the glands compared to neighbouring mucous and granular glands. Hypertrophied mental glands are larger than mucous or granular glands in all species, but relationships among caudal courtship glands and other skin glands vary among species. In E. quadridigitata, active caudal courtship glands are larger than mucous and granular glands, but in D. conanti, caudal courtship glands are similar in size to granular glands and larger than mucous glands. In P. mississippi, caudal courtship glands are scattered among significantly larger granular glands and are similar in size to mucous glands.

An annual cycle of gene regulation in the red-legged salamander mental gland: from hypertrophy to expression of rapidly evolving pheromones

“…Lectin staining suggested condensation and/or degradation of much of the ECM as the gland expanded ( Fig 2B). Immunohistochemical labeling with anti-PRF produced a strong, punctate pattern throughout the eosin-positive space, reflective of secretory vesicles observed in scanning electron microscopy [40]. There was minimal PRF staining for mid June, both in intensity and volume ( Fig 3).…”

Skin glands of an aquatic salamander vary in size and distribution and release antimicrobial secretions effective against chytrid fungal pathogens

“…For example, in some species of plethodontid salamander, males possess specialized granular glands located at the dorsal tail base termed 'caudal courtship glands'. These glands hypertrophy during the breeding season and are hypothesized to produce courtship pheromones (Rupp and Sever, 2018;Sever, 1989;Trauth et al, 1993). At the tail base of other salamanders, ventral granular glands (termed 'post-cloacal glands') synthesize chemosignals relevant to intraspecific interactions (Chouinard, 2012;Largen and Woodley, 2008).…”

“…swollen cloaca). To better understand the reproductive biology and social behaviors of this elusive species, future studies are needed to resolve whether granular glands located at the tail base are sexually dimorphic or undergo seasonal secretory cycles similar to courtship glands described for other species (Rupp and Sever, 2018;Sever and Siegel, 2015).…”

“…For example, while ordinary mucous glands constitutively release products rich in mucopolysaccharides and facilitate cutaneous gas exchange, specialized mucous glands synthesize protein pheromones used during courtship and mating (Woodley, 2015). Though the occurrence of specialized glands is widespread among terrestrial salamanders, the presence of similar glands in aquatic species remains largely unexplored (Rupp and Sever, 2018).…”

Sexual Isolation between Two Sympatric Desmognathus in the Gulf Coastal Plain

“…data). Histological studies of populations of D. conanti (SL) elsewhere in the Gulf Coastal Plain suggest that these glands do not fully atrophy and that males may be capable of breeding throughout the year (Rupp, 2016). Given the capacity for female plethodontids to store sperm for anywhere from two to greater than nine months (Marynick, 1971;Sever, 2003;Eddy et al, 2015) as well as the prolonged breeding season in some species, it is feasible that receptive adults of both D. aff.…”