Megachile (Chelostomoides) campanulae (Robertson, 1903)

Oligotropus campanulae Robertson, 1903: 171.

Megachile (Chelostomoides) campanulae; Mitchell 1934: 301; 1937d: 389; 1956: 136; 1962: 182. Raw 2002: 7. Gonzalez 2008: 37. Scott et al. 2011: 54. Sheffield et al. 2011: 28. Drons 2012: 58. Reese et al. 2018: 21. Delphia et al. 2019a: 24.

Chalicodoma (Chelostomoides) campanulae; Hurd 1979: 2073.

Megachile campanulae; Burkle et al. 2020: 7.

Chelosomoides (Chelosomoides) campanulae; Engel 2020: 10.

Oligotropus wilmingtoni Mitchell, 1924: 156.

Megachile angelarum, not Cockerell, 1902 (misidentification); Reese et al. 2018: 21. Delphia et al. 2019b: 24. Burkle et al. 2020: 7. LaManna et al. 2020: Supplementary Material pg. 40.

Diagnosis. The female of M. campanulae can be identified by its subparallel metasoma (viewed dorsally) (Fig. 6C), mandibles without cutting edges, clypeal margin that is medially emarginate and laterally crenulate, a medially incomplete T5 apical setal band that is thinner and less plumose than T1–4 apical setal bands, vertex of head with large, sparse punctation (ca. 4–6 punctures between lateral ocelli and posterior margin of vertex), close and evenly spaced scutum punctation compared to irregular and inconsistent scutellum punctation, and a line of punctures on the occipital suture appearing as a slight carina. Females of M. campanulae are most similar to M. angelarum (see M. angelarum above) (see Taxonomic Challenges). The male of M. campanulae can be identified by its retracted S4 and large, sparse punctation on the vertex of the head (ca. 4 punctures between lateral ocelli and posterior margin of vertex). Males of M. campanulae are most similar to M. angelarum (see M. angelarum above).

Notes. In Montana, M. campanulae has been collected in scattered western and eastern localities (Fig. 1E). These mason bees use plant resins, not leaves, to construct nest cells in existing cavities or trap nests (O’Neill & O’Neill 2016) and are therefore not leafcutting bees. Because of misidentifications noted above in the synonymical table, the morphological description of the female in Sheffield et al. (2011) is not accurate. See Table 2, Supplementary Material 2: Erroneous Records, and Taxonomic Challenges for further explanation.The vouchers for the misidentified specimens (Reese et al. 2018; Burkle et al. 2020; LaManna et al. 2020) are in the Burkle Community Ecology Lab at Montana State University identified as female M. campanulae (5718LR, 19730CHS, 68812LR, 64728LR, 1725CHS, 73A817LR). The vouchers for the misidentified specimens (Delphia et al. 2019b) are in the O’Neill Research Collection at Montana State University identified as female M. campanulae (KMOC #1435, KMOC #1436, KMOC #1437) (Table 2).