Fossil record of the mayfly family Ephemerellidae (Insecta: Ephemeroptera), with description of new species and first report of Ephemerellinae from Baltic amber

<p>The fossil record of the mayfly family Ephemerellidae is reviewed. Of previously described fossil Ephemerellidae, all records but one are doubtful or erroneous. We reinvestigate the holotype of <i>Ephemerella viscata</i> Demoulin, 1968 from Eocene Baltic amber and confirm its previous placement within the subfamily Timpanoginae Allen, <a href="#cit0001b" target="_blank">1984</a>, based on the presence of vestigial gill sockets on abdominal segments IV–VII only. It is transferred to the genus <i>Eurylophella</i> Tiensuu, <a href="#cit0053a" target="_blank">1935</a> [<i>Eurylophella viscata</i> (Demoulin, 1968) comb. nov.] based on proportions of the forelegs, elongated abdominal segment IX, and the shape of the subimaginal penis. Additionally, we describe two new specimens from Eocene Baltic amber: <i>Ephemerella trigonoptera</i> sp. nov. represents the first fossil record of subfamily Ephemerellinae. It can be separated from other representatives of <i>Ephemerella</i> Walsh, 1862 <i>sensu lato</i> by the shape of the hind wings, which are remarkably narrowed towards the apex, with a costal projection located rather proximally. The second new specimen, a male subimago, cannot be differentiated from other Ephemerellinae due to its poor preservation. The discovery of <i>Ephemerella trigonoptera</i> sp. nov., together with the taxonomic reassessment of <i>Eurylophella viscata</i> comb. nov., provide the first reliable evidence that both subfamilies of Ephemerellidae, Ephemerellinae and Timpanoginae, date back at least to the Palaeogene. The biogeographical and palaecological implications of these findings are discussed.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:B520497A-B28C-44C9-98E6-BE45D99608A2" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:B520497A-B28C-44C9-98E6-BE45D99608A2</a></p>