Megachile (Litomegachile) gentilis Cresson, 1872

Megachile gentilis Cresson, 1872: 267 .

Megachile (Litomegachile) gentilis; Mitchell 1935a: 23. Butler 1965: 3. Hurd 1979: 2053. Gonzalez 2008: 35. Sheffield et al. 2011: 36. Bzdyk 2012: 44. Sheffield and Heron 2019: 70.

Diagnosis. The female of M. gentilis can be identified by the black scopal setae on S6, white scopal setae on S2–5, and 4-toothed mandibles with an angulate basal mandibular tooth appearing as a weak additional tooth (i.e., 5- toothed) (Fig. 7D). The female of M. gentilis is closest to M. mendica, which has mostly yellow to light orange scopal setae on S6 but can approach ca. 50% black scopal setae apically. For further details on identification issues see Taxonomic Challenges. The male of M. gentilis can be identified by its narrow probasitarsus, which is not excavated ventrally, T5 without a white apical setal band (may have some setae laterally), and T4–5 dull with punctures ca. 1 diameter apart. The male of M. gentilis is closest to M. mendica, in which T4–5 is polished and shiny, with punctures 2–4 diameters apart.

Notes. This species is a new state record for Montana and has been collected from scattered localities in central and western Montana (Fig. 1N). Megachile gentilis nests in natural cavities as well as trap nests (Sheffield et al. 2011). Photographs, illustrations, full morphological descriptions, and notes on its biology can be found in Sheffield et al. (2011) and Bzdyk (2012).