Megachile (Xanthosarus) dentitarsus Sladen, 1919

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, Zootaxa 5683 (1), pp. 1-51 : 32

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).

Figures

FIGURE 1. County-level distribution of each Megachile species in Montana. Females identified as Megachile latimanus/ Megachile perihirta (and data without recorded specimen sexes) are counted here as M. perihirta as they are not distinguishable from one another in Montana. Males identified as Megachile lapponica/Megachile relativa (and data without recorded specimen sexes) are counted here as M. relativa as they are not distinguishable from one another in Montana. Mitchell county records are included on maps but not in specimen counts. Two specimens did not have county-level localities and are not included in maps but are included in specimen counts.

FIGURE 7. Female Megachile characters. (A–H) Anterolateral view of mandible, (I–N) Lateral view of metasoma, tergites 4–6, (O) Lateral view of tergites on M. dakotensis, and (P) Lateral view of head with pronounced tooth on the posterior genal margin on M. pugnata.

FIGURE 8. Male Megachile characters. (A) Probasitarsus not expanded or excavated ventrally, (B) Probasitarsus widely expanded and excavated ventrally, (C–E) Anterior view of mesobasitarsus and mesotibia, (F) Lateral view of triangular metatarsomeres on M. manifesta, (G) Lateral view of quadrate metatarsomeres on M. wheeleri, (H) Ventral view of procoxal spine, longer than wide, (I) Ventral view of procoxal spine, wide and spatulate, (J–L) Dorsal view of vertex of head: (J) Ocelloccipital distance longer than ocellocular distance, (K) Ocelloccipital distance equal to ocellocular distance, and (L) Ocelloccipital distance shorter than ocellocular distance.