Bees of the Pacific Northwest : key to species for Lasioglossum subgenera Lasioglossum and Leuchalictus (Hymenoptera : Halictidae)
Authors: Engler Joseph D. , Gorman Mark , Jackson August S. , Coleman Paris , Stanton Marek , Best Lincoln R. 
Published: February 2025

The following taxonomic key to the species of Lasioglossum Curtis, 1833 subgenera Lasioglossum and Leuchalictus Warncke, 1975 is adapted from McGinley (1986). This key is limited to those species known or expected to occur in Oregon based on McGinley (1986), and subsequent collection efforts in the Pacific Northwest by the U.S. Fish and Wildlife Service (Engler, et al 2018a-h; Engler and Stockenberg 2024a-g, Ikerd and Engler 2021) and the Master Melittologist Oregon Bee Atlas (Best et al 2021, 2022), as well as unpublished specimen records totaling 5,190 specimens. Additional species information was provided by Dr. Joel Gardner (Collections Manager, The M.T. James Entomological Collection, Washington State University, Pullman, WA). Prior to the species key, we provide an abbreviated key to enable the user to distinguish the subgenera covered in this guide from the other Lasioglossum subgenera in the region. This key is modified from the more complete subgeneric key provided by Gardner and Gibbs (2022). This key to species is intended for use by amateur and professional melittologists throughout the Pacific Northwest. The intent is to streamline the diagnosis of these species and provide updated figures to the salient characteristics required for identification. It amends McGinley’s 29 species north of the Mexican border to include the 15 species documented in the Pacific Northwest. One of those, L. leucozonium (Schrank, 1781), has not been documented in Oregon but is known from specimens in Washington (J. Gardner, pers comm). This species is not incorporated into the key, but is discussed in the footnotes underneath the related L. zonulus (Smith, 1848) with notes on differentiating the two species. This key does not replace the more detailed keys and species descriptions provided by McGinley (1986), therefore that publication should be consulted for additional information. Terminology follows the aforementioned keys as well as Michener (2007). The morphological characteristics used in the key are first and foremost from McGinley (1986), however physical specimens collected by the Master Melittologist Oregon Bee Atlas (Best et al 2021, 2022) and the U.S. Fish and Wildlife Service (Engler, et al 2018a-h; Engler and Stockenberg 2024a-g, Ikerd and Engler 2021) were studied to assess which characters would be most beneficial to amateur melittologists and to produce images. Fourteen of the fifteen species were coI-mtDNA barcoded to support morphological species boundaries but not used for identification. Barcodes highlighted species-recognition issues and uncertainty within the Lasioglossum trizonatum (Cresson, 1874) species group, an issue broached initially by McGinley. At this time, no effort has been made to resolve the incongruities within the barcoded specimens. Refer to the footnotes for more information. This key is applicable for a broad geographic region, covering far northern California and all of Oregon, Washington, Idaho, British Columbia, and Alaska. At the end of this document, species occurence maps are provided for 12 species in Oregon, using data collected through the Oregon Bee Atlas.