Megachile (Megachile) centuncularis (Linnaeus, 1758)

Apis centuncularis Linnaeus, 1758: 575 .

Megachile (Athemois) centuncularis; Mitchell 1935b.

Megachile (Megachile) centuncularis; Mitchell 1962: 124; 1980: 25. Butler 1965: 5. Hurd 1979: 2055. Ivanochko 1979: 145. Gonzalez 2008: 35. Scott et al. 2011: 55. Sheffield et al. 2011: 44. Sheffield and Heron 2019: 70.

Diagnosis. The female of M. centuncularis can be identified by its 5-toothed mandibles with evenly deep emarginations between all teeth (Fig. 7G), black setae on T6, and yellow to orange scopal setae on S2–6. It is most similar to M. relativa, which has golden setae on T6. The male of M. centuncularis can be identified by its narrow brown to black probasitarsi (Fig. 8A), sparse setae on T6, absence of a procoxal spine, and absence of a median tubercle on the clypeus. The male of M. centucularis is most similar to M. lapponica / M. relativa, which has a small triangular median tubercle on the clypeal margin.

Notes. This species is a new state record for Montana, though it is widespread elsewhere in North America. In Montana, it has been sparsely collected in a few western localities (Fig. 1G). Photographs, a full morphological description, and notes on the biology of this species can be found in Sheffield et al. (2011).