A New Record Mayfly Ephemerella subvaria McDunnough (Ephemeroptera, Ephemerellidae) from Ohio, USA

In the spring of 2019, a new state record for a mayfly (Ephemeroptera) was collected at Cedar Run and the Mad River in Champaign County, Ohio, United States. Ephemerella subvaria McDunnough, 1931, was collected and identified as nymphs and subsequently reared to adults. This Ohio location is exceptional. The geographic distribution of the species is widespread in the eastern United States; however, its distribution in the upper midwest is limited to northern Michigan and northern Wisconsin, but is absent from the southern counties of those states, and from Illinois. It is rare in Indiana and northern Kentucky. Until this report it was unknown from Ohio. Nymphs were collected on 26 March 2019. Reared in a temperature-controlled aquarium, the subimago emerged on 27 April 2019 and the imago emerged on 30 April 2019. It is hypothesized that Cedar Bog Nature Preserve, Cedar Run, and the Mad River—remnants of streams in a prior swamp in western-central Ohio—provide a refugia for this out-of-place species.