The mechanistic origin of amber pigmentation of Perithemis tenera (Say, 1840) wings (Anisoptera: Libellulidae)

Animal coloration serves various signaling and non-signaling functions. In damselflies and dragonflies (Odonata), such colors may not only play photoprotective and/or thermoregulatory roles but also serve as visual signals during courtship and/or agonistic interactions. Here, we analyzed the coloration of Perithemis tenera wings, a potential secondary sexual ornament, applying spectrophotometry and visual modeling to gain a deeper understanding of their color mechanisms and functions. The amber coloration of the P. tenera wings results from the interaction of light with both the melanized chitin matrix and possibly ommochrome pigments. This coloration stands out significantly against the dry Brazilian savannah, the natural habitat of P. tenera, making it easily detectable by conspecifics. Additionally, by fitting the absorbance curve of P. tenera wings to the extinction coefficient of different melanins, we deduced that pheomelanin is likely the pigment embedded in the wing’s chitinous matrix. If the presence of pheomelanin is confirmed, a pigment predominantly found in vertebrates and known to be associated with an increased risk of melanoma and Parkinson’s disease, P. tenera could become a valuable species for studying these diseases and their potential links to pigmentation, as well as its roles in insects’ immune systems and cuticle sclerotization.