“Sexual tears” in a salamander?

Abstract

G. Kingsley Noble reported the possibility of orbital gland involvement in reproduction of spelerpine salamanders, particularly Eurycea, through rudimentary gross examination of the heads of male and female salamanders. In his report, Noble provided details from only one taxon of salamander, E. bislineata. To examine the variability of orbital glands with secondary sexual function in Eurycea, orbital glands of E. longicauda were assessed for sexual dimorphism and a distinct seasonal secretory cycle that mirrored the reproductive cycle. Orbital glands were found not to be sexually dimorphic in E. longicauda and possessed constant secretory activity in males and females throughout the year. Known secondary sexual glands (mental glands, caudal courtship glands, and cloacal glands) were sexually dimorphic between males and females and possessed a secretory cycle that could be correlated with events of the reproductive cycle, particularly mating activity. Thus, no evidence was found for orbital gland involvement in reproduction in E. longicauda. Orbital glands of both male and female E. longicauda are morphologically identical and produce copious lipoproteins throughout the year. Orbital gland secretions are potentially involved in lubrication of the eye and the prevention of fluid evaporation from the eye as described for lipoprotein secretions in other vertebrate lineages.