Revision of the damselfly Hesperagrion praevolans (Odonata, Zygoptera, Coenagrionidae) from the uppermost Eocene of Florissant (Colorado, USA)

The damselfly family Coenagrionidae is rather frequently found in the Cenozoic fossil record (Nel & Paicheler, 1993), but it remains unknown in the Mesozoic. The known fossils are generally isolated wings, very difficult to accurately attribute to precise genera, to the point that many fossils can be only considered as ‘genera and species undetermined’ (Nel et al., 1997). The oldest described coenagrionid fossil is the late Palaeocene Marado marado Petrulevičius, 2021 (Maíz Gordo Formation, Argentina), a genus and species based on an isolated incomplete wing. Thus, other Eocene representatives of the family are important for future accurate dating of the occurrence of the family and its subdivisions, especially those that have been attributed to extant genera; a future step after the important work of Dijkstra et al. (2014) for the understanding of the evolution of these damselflies.