Megachile (Xanthosarus) dentitarsus Sladen, 1919 Megachile dentitarsus Sladen, 1919: 85. Drons 2012: 58. Adhikari et al. 2019: Supplementary Table S4. Megachile (Xanthosarus) dentitarsus; Mitchell 1936: 127. Butler 1965: 11. Hurd 1979: 2067. Scott et al. 2011: 56. Sheffield et al. 2011: 73. Diagnosis. The female of M. dentitarsus can be identified by its consistently wide, white apical setal bands on T3–5 and its 5-toothed mandibles (Fig. 7F), with the deepest emargination between the 3 rd and 4 th tooth, strongly angled towards the 4 th tooth. Females are most commonly confused with M. latimanus / M. perihirta females, which have medially incomplete apical setal bands. The male of M. dentitarsus can be identified by its widely expanded and ventrally excavated probasitarsus (Fig. 8B), the smooth, glabrous ventral protuberance on its mesobasitarsus (Fig. 8D), and the small spine on the ventral mesepisternum (viewed ventrally, directly anterior to mesocoxa). Males are most similar to M. perihirta, in which the ventral mesepisternum (viewed ventrally, directly anterior to mesocoxa) has a smooth, spineless carina instead of a spine. Notes. In Montana, this species is widespread east of the continental divide (Fig. 1J). Photographs, a full morphological description, and notes on the biology of this soil-nesting species can be found in Sheffield et al. (2011).

Published as part of Pritchard, Zoe A., Ivie, Michael A., O'Neill, Kevin M. & Delphia, Casey M., 2025, A faunal treatment of the Megachile (Hymenoptera: Megachilidae) of Montana with a key for their identification, pp. 1-51 in Zootaxa 5683 (1) on page 32, DOI: 10.11646/zootaxa.5683.1.1, http://zenodo.org/record/16984989