Megachile (Megachile) lapponica Thomson, 1872

Megachile lapponica Thomson, 1872: 227 .

Megachile (Megachile) lapponica; Sheffield et al. 2011: 47. Kuhlman and Burrows 2017: 13. Reese et al. 2018: 22. Delphia et al. 2019a: 24. Sheffield and Heron 2019: 70.

Megachile nivalis Friese, 1903: 246 .

Megachile (Anthemois) santiamensis Mitchell, 1934: 311 .

Megachile (Anthemois) nivalis; Mitchell 1935b: 174; 1942: 115.

Megachile (Megachile) nivalis; Mitchell 1962: 129. Hurd 1979: 2056. Ivanochko 1979: 170. Sheffield and Westby 2007: 178. Scott et al. 2011: 55.

Diagnosis. The females of M. lapponica can be identified by their5-toothed mandibles with evenly deep emarginations between teeth (Fig. 7G), brown to black scopal setae on S6, and scopal setae on S5 black apically and yellow to pale orange basally. The female of M. lapponica is most similar to M. relativa, which has golden scopal setae on S6, and M. centuncularis, which has black setae on T6. The males of M. lapponica cannot be reliably separated from males of M. relativa in Montana based on external morphology or by examining the genitalia (see Taxonomic Challenges; Sheffield & Westby 2007). Males of M. lapponica / M. relativa can be recognized by the absence of a procoxal spine, small median triangular tubercle on the clypeal margin, narrow brown to black probasitarsi, evenly spaced 3-dentate mandibles, and T6 with sparse setae, not tomentose. Megachile lapponica / M. relativa is most similar to M. centuncularis (see M. centuncularis above).

Notes. Megachile lapponica females have been found in scattered localities across the western half of Montana (Fig. 1P). Photographs, a full morphological description (but see Taxonomic Challenges), and notes on the biology of M. lapponica can be found in Sheffield et al. (2011).