The evolution of abdomen and flight style diversity within the dragonfly genus Erythemis Hagen, 1861 (Anisoptera: Odonata)

The dragonfly genus Erythemis Hagen 1861, in the hyper-diverse family Libellulidae Leach, 1815, contains considerable variation in abdomen shape and flight style. While Erythemis has historically been known as a genus of perching dragonflies, Erythemis vesiculosa (Fabricius, 1775) is an active flier. Qualitative observations of body type show differences in thickness of abdomen, which may relate to flight style and aerodynamics. To understand the evolutionary origins of potentially correlated flight adaptations and behavior, a robust phylogeny is needed for the genus. Here, we present the most comprehensively sampled phylogenetic reconstruction for Erythemis based on anchored hybrid enrichment (AHE) DNA sequences. Our phylogeny includes all ten Erythemis species, plus outgroup species from other libellulid genera thought to be closely related to Erythemis. Employing the maximum- likelihood-inferred phylogeny, we performed a likelihood-based ancestral character state reconstruction to test morphological synapomorphies for the group; in particular, we tracked interspecific variation in male secondary genitalia morphology and assessed the evolution of flight style and quantified abdomen measurements. Using reliable Erythemis fossils as calibration, we estimated the origin time of the genus and of changes in flight style. We also performed a biogeographical analysis to determine how the genus diversified across the Western Hemisphere, with a majority of its ten species in Central and South America. Thus, we assessed the evolutionary relationships of all ten Erythemis species, the origins and timing of flight style and abdomen thickness innovations, and the historical range of the group.