Leafcutter and Mason Bees of the Genus Megachile Latreille (Hymenoptera: Megachilidae) in Canada and Alaska1
CJAI 18 November 29, 2011

Cory S. Sheffield*2, Claudia Ratti*, Laurence Packer*, Terry Griswold**

*Department of Biology, York University 4700 Keele St., Toronto, ON M3J 1P3 coryshefield@yahoo.ca; cratti@yorku.ca; xeromelissa@mail.com. **USDA-ARS Bee Laboratory, Utah State Univ., Natural Resources Biology Bldg. Logan, UT 84322 Terry.Griswold@ars.usda.gov.

1This paper is contribution #12 from the Canadian Pollination Initiative. 2Corresponding Author.

          Leafcutter and mason bees of the genus Megachile are common members of the North American bee fauna and many Megachile species are important pollinators of summer flowering crops and native plant species. Despite this, no comprehensive account of species in Canada and Alaska has been published. Our objective is to provide an up-to-date revision of the genus Megachile of this region, including an interactive key to the species, and summaries of biogeographic distribution and life history. Additionally, divergence in a 658 bp segment of the mitochondrial COI gene (the “DNA barcode” region) was used to clarify the taxonomic status of several Megachile species in North America. Based on morphological differences and over 6% sequence divergence in COI, M. (Litomegachile) onobrychidis Cockerell, previously considered a subspecies of M. (Litomegachile) brevis Say, is recognized here as a valid species. Similarly, M. (Litomegachile) pseudobrevis Mitchell, found in the southeastern United States, is also considered a distinct species and removed from synonymy with M. brevis. Megachile (Eutricharaea) apicalis Spinola and M. (Megachiloides) casadae Cockerell and M. (Megachiloides) umatillensis (Mitchell) are recorded from Canada for the first time; M. (Xanthosarus) giliae Cockerell and M. (Megachile) nivalis are placed into synonymy with M. (Xanthosarus) circumcincta (Kirby) and M. (Megachile) lapponica Thomson, respectively, and are thus considered Holarctic in distribution; M. subanograe Mitchell is placed into synonymy with M. sublaurita Mitchell (previously only known from its melanistic female form), and the male is described for the first time. Megachile (Megachiloides) alamosana Mitchell, known only from the male, M. (Megachiloides) laurita Mitchell, and M. (Megachiloides) laurita semilaurita Mitchell (both melanistic female forms) are placed into synonymy with M. (Megachiloides) anograe Cockerell, the latter three species previously only known only from the females. Full descriptions of all 38 species found in Canada and Alaska are provided.

Megachile latimannus Photo by Stephen A. Marshall

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