Megachile (Sayapis) fidelis Cresson, 1878

Megachile fidelis Cresson, 1878: 120 . Drons 2012: 58.

Megachile (Sayapis) fidelis; Mitchell 1937c: 180. Butler 1965: 12. Hurd 1979: 2070. Ivanochko 1979: 325. Scott et al. 2011: 56. Sheffield et al. 2011: 64. Kuhlman and Burrows 2017: 13. Reese et al. 2018: 22. Sheffield and Heron 2019: 70. Engel 2020: 10.

Diagnosis. The female of M. fidelis is distinguished by its subparallel metasoma (viewed dorsally) (Fig. 6C) and clypeal margin with two prominent, wide, lateral tubercles surrounding a median triangular tubercle (Fig. 6F), which is unique among documented Montana Megachile species. The male of M. fidelis is distinguished by its thin and narrowly pointed procoxal spine (Fig. 8H) and its widely expanded and ventrally excavated probasitarsus (Fig. 8B) with dark setae along the entire posterior edge of the scoop-shaped dilation. The male of M. fidelis is most similar to M. pugnata, which has dark setae along only the basal ⅓ of the posterior edge of the scoop-shaped dilation.

Notes. This species has been recorded mainly in western Montana (Fig. 1K), with one record further east in Musselshell County, but it would be expected to be found in the eastern half of the state due to a record of M. fidelis from the Black Hills of South Dakota (Drons 2012). Photographs, a full morphological description, and notes on the biology of this cavity-nesting species can be found in Sheffield et al. (2011).