Stoneflies are a relatively small order of insects comprising over 4,200 extant, described species. They have long been recognised as valuable indicators of water quality, since nymphs are dependent on clean water conditions and are sensitive to the effects of sedimentation and pollution. It is also well-documented that stonefly species around the world have suffered contractions in range, leading, in some cases, to local extirpation or extinction. West Virginia is home to high stonefly species richness relative to most other USA (United States of America) states. Despite this diversity, the available literature is scattered and occurrence datasets supported by voucher specimens are non-existent. Funding from the U.S. Fish and Wildlife Service and a consortium of northeastern USA states has provided an opportunity to document the stonefly fauna of West Virginia, especially for state and regional species of conservation interest, by gathering specimen-based occurrence data from museums, collecting new specimens statewide, and compiling trusted literature records into a single statewide dataset. Our hope is that the records presented in this data paper will further the understanding of stonefly species distribution in West Virginia and the eastern USA in general, and provide conservation agencies with usable temporal and locality data. These data will be used as the basis of an upcoming distribution atlas and annotated checklist of the stoneflies of West Virginia.

Our dataset brings together over 4,500 stonefly records from all 55 counties in West Virginia. These records, spanning the previous 134 years, have been contributed by 17 institutions and personal collections. Through new collecting and the examination of museum specimens, we have been able to verify the presence of 150 species, with representatives from all nine eastern North American families. Fourteen species previously recorded from West Virginia, comprising seven Perlodidae, six Perlidae and one Chloroperlidae, have not been recovered. Most of these absences can be accounted for by changes in taxonomic nomenclature. In addition to 140 species already known from the state, we report the presence of 11 new state records, including four Perlidae, three Perlodidae, two Capniidae, one Leuctridae and one Nemouridae.