1. In dragonflies, species richness shows a marked variation between lineages. Species diversification in this lineage has been linked with habitat variation, but the role of other factors, such as wing pigmentation, arguably one of the most conspicuous traits in dragonflies, have not yet been explored.2. In this study, using novel methodology that takes into account state-dependent speciation, extinction models, and ancestral reconstruction, we investigate the role of wing pigmentation (present/absent) in conjunction with habitat variation (lentic/ lotic), to unveil the drivers of species diversification in dragonflies.3. We found that wing pigmentation is associated with a marginal increase in diversification compared to unpigmented lineages. Inhabiting a lentic habitat is associated with higher diversification rates. When considering both factors in a single model, lentic environments are associated with higher diversification compared to lotic habitats regardless of pigmentation status. In contrast with results across the whole tree, in lotic environments, wing pigmentation is associated with marginally higher diversification rates compared to non-pigmented species. Ancestral state reconstruction revealed that the last common ancestor of dragonflies was most likely non-pigmented and lived in lotic habitats. 4. Our study provides evidence that wing pigmentation in conjunction with habitat has an important influence on dragonflies species diversification, with habitat being a better differentiator than wing pigmentation.

Sexual selection has long been thought to promote speciation, but evidence is inconclusive. In Odonata - which includes dragonflies and damselflies-, wing pigmentation has been found to be influenced by sexual selection. Past evidence shows that wing pigmentation in males is a driver of speciation in damselflies. However, whether sexual dimorphism per se is associated with species diversification rates has not been tested. Here we test whether wing pigmentation sexual dimorphism influences diversification rates in a supertree of 1,260 species, the most comprehensive phylogeny inferred for the group. We find that male wing pigmented sexual dimorphism is associated with higher species diversification rates in damselflies but not in dragonflies. This study presents the first evidence of the role of species sexual dimorphism in species diversification in a clade identified as amarker of habitat quality. In the face of accelerating biodiversity loss, uncovering diversification drivers is of pressing importance.