The femoral gland is a specialised gland found in some male frogs that plays a role in chemical communication and reproductive signalling. Particularly prominent within the frog family Mantellidae, these glands are located on the underside of the hindlimbs, usually on the inner thighs or shanks. Femoral glands can be identified by their swollen appearance and distinct colouration, which differ from the surrounding skin. Femoral glands are classified into four distinct morphological types, varying from minute granular structures to conspicuous patches characterised by large granules and prominent central indentations.
Femoral glands in certain frogs, particularly in the subfamily Mantellinae, are implicated in reproductive signalling and species recognition, affecting behaviours like oviposition. These glands, which develop early in species like Nyctibatrachus major, are subject to hormonal and environmental influences. Unlike the amplexus (sexual clasp) observed in other anuran frogs, Mantellinae males employ these glands in a unique, loose mating clasp. The volatile organic compounds secreted by the glands serve a chemical communication role that influences mating behaviour. Research indicates that compounds from femoral glands in mantellid frogs can specifically activate olfactory neurons, responsible for detecting and transmitting odour signals to the brain. Structural variations in the femoral glands assist in the taxonomic differentiation of some frog species and genera.