The damselfly genus Furagrion Petrulevicius et al. (Odonata, Zygoptera) from the early Eocene Fur Formation of Denmark and the dysagrionoid grade

The earliest Eocene odonate genus Furagrion Petrulevicius et al. from the Danish Fur Formation is revised based on eighteen specimens, two of which apparently have been lost since their publication. The holotype of Phenacolestes jutlandicus Henriksen, type species of Furagrion, is incomplete and lacks the characters currently used to differentiate species, genera and higher taxa in Odonata. We, therefore, propose that the holotype is set aside and a recently discovered nearly complete Fur Formation fossil is designated as neotype. Furagrion possesses all of the nine wing character states currently used along with head shape for diagnosing the Dysagrionidae; however, Furagrion has a characteristically zygopteran head, not the distinctive head shape of the suborder Cephalozygoptera. We, therefore, treat it as a zygopteran unassigned to family. These nine wing character states appear in different combinations not only in various Zygoptera and Cephalozygoptera, but also in the Frenguelliidae, an Eocene family of Argentina that may represent an unnamed suborder. We recognise these taxa as constituting a dysagrionoid grade, in which these character states appear either convergently or as symplesiomorphies. Furagrion morsi Zessin is synonymized with Phenacolestes jutlandicus Henriksen, syn. nov. and Morsagrion Zessin with Furagrion Petrulevicius, Wappler, Wedmann, Rust, and Nel, syn. nov.

Automated summary

The early Eocene odonate genus Furagrion Petrulevicius et al. from the Danish Fur Formation is revised, and a nearly complete Fur Formation fossil is designated as neotype. Furagrion is a zygopteran unassigned to family, possessing the wing character states used to diagnose the Dysagrionidae but lacking the distinctive head shape of the Cephalozygoptera suborder. These wing character states appear in different combinations not only in various Zygoptera and Cephalozygoptera, but also in the Eocene family Frenguelliidae, possibly representing an unnamed suborder. Furagrion morsi Zessin is synonymized with Phenacolestes jutlandicus Henriksen, syn. nov., and Morsagrion Zessin with Furagrion Petrulevicius, Wappler, Wedmann, Rust, and Nel, syn. nov.