Open Access

Thomas M. Onuferko, Cory S. Sheffield

• A new species of Epeolus Latreille, 1802 (Hymenoptera: Apidae)—E. emiliae Onuferko and Sheffield, new species—is described from North America west of the Great Plains. It is morphologically most similar to Epeolus autumnalis Robertson, 1902, a species known exclusively from east of the Rocky Mountains. DNA barcode sequences from representatives of E. autumnalis and E. emiliae share a barcode index number (i.e., BIN: BOLD:AAF2361), but the two species exhibit marked and consistent differences in integument coloration and the patterns of pubescence on the metasoma, and their distributional ranges, based on known specimens, show no overlap. This discovery increases the number of species of Epeolus confirmed in Canada to 14, and North America north of Mexico to 44. Modifications to existing identification keys to Canadian and all North American species of Epeolus are provided, as well as a differential diagnosis, to enable the identification of E. emiliae. Additionally, three new provincial records are reported for species of Epeolus occurring in Canada: E. interruptus Robertson, 1900 from Alberta and Quebec and E. scutellaris Say, 1824 from Saskatchewan. ZooBank registration: urn:lsid:zoobank.org:pub:811B569E-9BF6-4319-B1FA-DD7A357B0847