LAUSR

Abstract. We repeatedly sampled 8 sites on the Crooked River in British Columbia's Arctic watershed for adult and nymph mayflies (Ephemeroptera) over the course of 2 years. Using taxonomic keys and DNA barcoding, we report 8 new species records for the province: 5 members of the family Baetidae (Acerpenna pygmaea, Baetis phoebus, Baetis vernus, Iswaeon anoka, and Procloeon pennulatum), 1 Heptageniidae (Leucrocuta hebe), 1 Leptohyphidae (Tricorythodes mosegus), and 1 Siphlonuridae (Siphlonurus alternatus). Three of these, Acerpenna, Iswaeon, and Leucrocuta, are also new genus records for the province. In total, we detected 40 species in 8 families as indicated by clustering into BINs (Barcode Index Numbers), by morphological keys, and by matches in the Barcode of Life Database. One of those species, Ameletus vernalis, is of conservation concern. Our analysis indicated that a number of other specimens may represent new species or genus records for British Columbia. In addition, this unique and anthropogenically impacted river may contain cryptic species of Baetis tricaudatus (Baetidae), Leptophlebia nebulosa (Leptophlebiidae), and Paraleptophlebia debilis (Leptophlebiidae).