Diversity of Armenian mayflies (Ephemeroptera) with the description of a new species of the genus Ecdyonurus (Heptageniidae).

We provide the first commented checklist of Armenian mayflies, based on all relevant literature and recent extensive sampling of 72 localities throughout Armenia during 2011, 2014, and 2015. Altogether 46 species are listed, eight of them reported from Armenia for the first time. One new species, Ecdyonurus (Ecdyonurus) eurycephalus sp. nov. is described (larva and male imago) based on morphological and molecular (COI) data. The species is characterized by a unique head shape in male imago and by the presence of tracheal filaments on gill plate VII in the larval stage.