Megachile (Chelostomoides) angelarum Cockerell, 1902

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 : 28

Megachile (Chelostomoides) angelarum Cockerell, 1902

Megachile angelarum Cockerell, 1902: 70 . Burkle et al. 2020: 7.

Megachile (Chelostomoides) angelarum ; Mitchell 1937d: 386; 1956: 131. Sheffield et al. 2011: 26. Kuhlman and Burrows 2017: 12 . Reese et al. 2018: 21 . Delphia et al. 2019a: 24 . Sheffield and Heron 2019: 69.

Chalicodoma (Chelostomoides) angelarum (Cockerell) ; Butler 1965: 15. Hurd 1979: 2073.

Diagnosis. The female of M. angelarum can be recognized by its subparallel metasoma (viewed dorsally) ( Fig. 6C ), mandibles without cutting edges, clypeal margin that is medially emarginate and laterally crenulate, white T5 apical setal band which is similar in width and appearance to the T1–4 apical setal bands, vertex of head with small, dense punctation (ca. 8–10 punctures between lateral ocelli and posterior margin of vertex), and a smooth, shiny, impunctate occipital suture. The female of M. angelarum is most similar to M. campanulae , which has a medially incomplete T5 white apical setal band that is thinner and less plumose than those on T1–4, and large, sparse punctation on the vertex of head (ca. 4–6 punctures between lateral ocelli and posterior margin of vertex) (see Taxonomic Challenges). The male of M. angelarum can be distinguished by its retracted S4 and dense punctation on the vertex of the head (ca. 9 punctures between lateral ocelli and posterior margin of vertex). Male M. angelarum are most similar to M. campanulae , which have large, sparse punctation on the vertex of the head (ca. 4 punctures between lateral ocelli and posterior margin of vertex).

Notes. These mason bees use plant resins, not leaves, to construct nest cells in existing cavities and are therefore not leafcutting bees. This species was first recorded in the published literature from Montana in 2017 from Missoula County, though the earliest recorded specimen year is 2015 ( Kuhlman & Burrows 2017; Table 1). It is now known from five counties in Western Montana ( Fig. 1A ). For further details on identification issues see Taxonomic Challenges. Photographs, a full morphological description, and notes on the biology of this 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 6. Female Megachile characters. (A) Ventral view of metasoma with white apical setal bands on S2–6, (B) Dorsal view of rounded metasoma, widest at T2–3, (C) Dorsal view of subparallel metasoma, (D–H) Anterior view of clypeus: (D) M. apicalis, (E) M. mellitarsis, (F) M. fidelis, (G) M. lippiae, (H) M. coquilletti, (I) Lateral view of mandible gradually tapering in width towards apex, (J) Lateral view of mandible with base square-shaped with parallel sides for a distance as long as wide, then tapering apically, and (K) Lateral view of mandible square basally, with sides parallel for approximately ⅓ the length of mandible, then tapering apically.