Megachile (Xanthosarus) frigida Smith, 1853

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) frigida Smith, 1853

Megachile frigida Smith, 1853: 193 . Drons 2012: 58.

Megachile (Delomegachile) frigida ; Mitchell 1942: 116; 1944: 135; 1962: 133. Butler 1965: 6. Hurd 1979: 2059. Ivanochko 1979: 195.

Megachile (Xanthosarus) frigida ; Scott et al. 2011: 56. Sheffield et al. 2011: 76. Reese et al. 2018: 22 . Delphia et al. 2019a: 25 . Delphia et al. 2019b: 649 . Sheffield and Heron 2019: 70.

Megachile (Delomegachile) frigida appalachensis Mitchell, 1962: 134 .

Megachile (Delomegachile) vidua var. appalachensis Mitchell, 1935b: 205 .

Megachile vidua , not Smith, 1853 (misidentification); Fultz 2005: 134.

Diagnosis. The female of M. frigida can be identified by its 4-toothed mandibles with a truncate basal mandibular tooth ( Fig. 7E ), dark brown to black setae on T6, and mostly yellow to orange scopal setae on S6. The female of M. frigida is most similar to M. latimanus / M. perihirta , which has 5-toothed mandibles ( Fig. 7F ) and orange setae on T6. The male of M. frigida can be identified by its widely expanded and ventrally excavated probasitarsus ( Fig. 8B ) and two brown stripes on the ventral profemur, which is unique among male Megachile documented in Montana.

Notes. This widespread, distinctive species is found across Montana, though it has been sparsely collected in the eastern half of the state ( Fig. 1L ). It is known to nest in rotting logs, cavities, and bark mulch ( Sheffield et al. 2011; Delphia et al. 2019b). Photographs, a full morphological description, and notes on the biology of this species can be found in Sheffield et al. (2011). The voucher for the misidentified specimen ( Fultz 2005) is in the MTEC identified as a male M. frigida (MTEC 088592) ( Table 2; Supp. Material 2: Erroneous Records).

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.