A Plethodontid Salamander without a Mental Gland (Ensatina eschscholtzii) Has Courtship-Like Glands on its Snout

Male Ensatina eschscholtzii do not have a mental gland, a macrogland used by males during courtship that is considered an ancestral character of plethodontids. We tested whether males and females have nonmental courtship glands associated with the integument of the rostrum and mentum (chin). We found that both male and female E. eschscholtzii possess courtship-like integumentary glands (modified granular glands) in the upper labia extending dorsally along the rostrum and lower labia extending ventrally across the mental region. These glands are sexually dimorphic in size (larger in females) and react positively with periodic acid–Schiff. We hypothesize that these glands are involved in courtship through production of pheromones that may or may not be similar to pheromones produced in courtship glands of other plethodontid salamanders. These rostral glands are structurally and chemically unique in comparison with glands of the rostrum that empty along the length of nasolabial grooves (nasolabial glands) of Ensatina, which do not appear to be involved in pheromone production. Both females and males have relatively few traditional mucous glands throughout the skin in comparison with other species of plethodontids, although some clusters are identified at the anterior edges of the labia.