Potential chemosignals associated with male identity in the amphisbaenian Blanus cinereus.

Pheromone-based chemosensory sex discrimination occurs in many reptiles, but the specific chemosignals responsible for this discrimination have been rarely identified. Chemoreception is especially important for amphisbaenians, a group of fossorial, almost blind, reptiles. We analyzed the role of semiochemicals produced by precloacal glands in intraspecific communication and chemosensory sex recognition of the amphisbaenian Blanus cinereus. We expected that sexual discrimination in amphisbaenians would be based on those chemicals that show intersexual differences in precloacal secretions, with squalene being the chemical that shows the greatest difference in relative abundance between sexes. Tongue-flick assays and behavioral responses to the scent of conspecifics confirmed that amphisbaenians are capable of detecting and discriminating between scent of conspecific males and females by using chemosensory cues alone. Differential responses of amphisbaenians to chemical compounds that are naturally found in precloacal secretions indicated that males can readily discriminate between different chemicals. Squalene, in particular, elicited in male amphisbaenians' chemosensory and aggressive responses that were similar to those elicited by precloacal secretions. This result suggests that squalene alone allows male discrimination by male amphisbaenians. Furthermore, squalene might also signal dominance status or aggressiveness of a male amphisbaenian because higher concentrations of squalene elicited higher levels of aggression by males.