Lipophilic compounds in femoral secretions of males and females of the El Hierro giant lizard Gallotia simonyi (Lacertidae)

• We analyze with GC–MS the femoral secretion of male and female El Hierro giant lizard.
• Main compounds are steroids and fatty acids.
• There are differences between sexes in presence and abundance of compounds.
• We discuss the potential function of some compounds in intraspecific communication.
• Secretions might be used to monitor health state of this endangered lizard.

Many lizards use femoral gland secretions in reliable intraspecific communication. Based on mass spectra, obtained by GC–MS, we found 57 lipophilic compounds in femoral secretions of males and females of El Hierro giant lizards, Gallotia simonyi (fam. Lacertidae). Compounds included steroids (mainly cholesterol) and fatty acids ranging between n-C16 and n-C22 (mainly hexadecanoic and octadecanoic acids), followed by aldehydes, alcohols, ketones, squalene and waxy esters. There were important intersexual differences in the presence, abundance and number of compounds (more numerous in males). Males had higher proportions of the most odoriferous compounds (fatty acids and aldehydes), while females had higher proportions of more stable compounds (steroids, waxy alcohols, waxy esters and terpenoids). This suggests sexual differences in function of femoral secretions. In addition, some compounds could reflect the physiological state, allowing monitoring health of lizards from secretions samples, which is especially important given the critical conservation status of this lizard.