Sexual dichromatism and throat display in spectacled salamanders: a role in visual communication?

Sexual dichromatism in animals is usually associated with mating displays and is linked to strong sexual selection. Among amphibians, it has mostly been reported in anurans and only in a few caudates. Here, we investigated sexual dichromatism in the only two extant species of the genus Salamandrina, testing for its possible role in intraspecific communication during the mating rituals of these terrestrially mating salamanders. In both S. terdigitata and S. perspicillata, we highlighted that males have more conspicuous ventral colourations, yet this is limited to the throat region, namely featuring rounder, larger and brighter gular white patches than females. We also described a new mating ritual behaviour performed by male S. perspicillata, that is, a stereotyped throat hyperextension, that enhances the visibility of the dimorphic colouration of the gular region of males, presumably representing a visual cue directed to females. We thereby discuss the potential role of sexual dichromatism in sexual selection and the evolutionary history of the genus Salamandrina.