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Dryad

Species and sex specific chemical composition in a concealed gland from an internal gland-like tissue of an African frog family

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Dec 12, 2023 version files 1.80 MB

Abstract

Intraspecific chemical communication in frogs is understudied and the few published cases are limited to externally visible and male-specific breeding glands. Frogs of the family Odontobatrachidae, a West African endemic complex of five morphologically cryptic species, have large, fatty gland-like strands along their lower mandible. We investigated the general anatomy of this strand and analyzed its chemical composition. We found the strand to be present in males and females of all species. The strand varies in markedness, with well-developed strands usually found in reproductively active individuals. Although the strands are situated under the skin, they are connected to particular skin sections, the vocal sac in male frogs and a respective area in females. Gas-chromatography/mass spectrometry and multivariate analysis revealed, that the strands contain sex- and species-specific chemical profiles, which are consistent across geographically distant populations. The profiles varied between reproductive and non-reproductive individuals. Our results indicate that the gland-like strand in the Odontobatrachidae comprise a so far overlooked type of breeding related organ, potentially a gland, that most likely plays a role in the mating and/or breeding behavior of the five Odontobatrachus species. Our results highlight the relevance of multimodal signaling in anurans, and indicate that chemical signaling may not be restricted to sexually dimorphic, apparent skin glands.