Megachile Potentially

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 : 42-43

Unrecorded Megachile Potentially in Montana

Eight North American species of Megachile are recorded in literature and databases occurring close to or in continuous landscapes with Montana but have not yet been recorded in the state. These species are predicted to possibly occur in Montana and may be uncovered through further faunistic work. Many species on this list (e.g., Megachile wyomingensis , Megachile latita , and Megachile hookeri ) are very rarely collected and have not been critically examined since Mitchell, who may have had only one to very few specimens. All need a review as part of a comprehensive revision.

Megachile (Xanthosarus) circumcincta (Kirby) is a boreal species ranging from Alaska through British Columbia and Alberta into northern Saskatchewan ( Mitchell 1935b; Sheffield et al. 2011; Sheffield 2021). It has also been recorded from the mountains of Colorado ( Mitchell 1935b; Scott et al. 2011 = Megachile giliae Cockerell ). With records both north and south of Montana, this species is predicted to occur widely in Montana.

Megachile (Megachiloides) hookeri Cockerell , which Mitchell states may be a color variation of M. nevadensis ( Mitchell 1937a) , was collected 200 km away from the Montana border in Pavillion, Wyoming (BBSL518981). It is also recorded in Lehi, Utah ( Mitchell 1937a), and Colorado ( Scott et al. 2011). From the Wyoming record, we predict M. hookeri may be found in the south-central badlands region of Montana near Bridger.

Discover Life shows an unvouchered Montana centroid record for Megachile (Sayapis) inimica Cresson (Discover Life 05 May 2021). There is a specimen record near Montana from Moran, Wyoming (AMNH UID653582), the identification of which was verified by Corey Smith (pers. com., 24 Mar 2021). As this species is also recorded close to the Wasatch Range in Willard, Utah (BBSL519969), we predict M. inimica may occur in southwest Montana, especially in the Centennial Valley (Beaverhead Co.) and surrounding area.

Megachile (Megachiloides) latita Mitchell was recorded in badland habitats in Worland, Wyoming and Maybell, Colorado ( Mitchell 1934). As Worland is near the Montana border, we predict this species may occur in south-central Montana in the contiguous xeric area south of Bridger .

Megachile (Leptorachis) petulans Cresson has been recorded to occur widely in the eastern, southern, and central U.S. but has fewer western records (Discover Life 01 June 2021, Mitchell 1937b). As it has been recorded from Jamestown, North Dakota ( Mitchell 1937b), a prairie pothole region, it would possibly be found in the prairie pothole region of northeast Montana near Plentywood and Caldera, approaching the North Dakota and Saskatchewan borders.

Megachile (Megachiloides) umatillensis (Mitchell) was recorded from Cornish, Utah, near the Wasatch Range (SEMC416330, Discover Life, 05 May 2021), in southern British Columbia ( Sheffield et al. 2011; Sheffield & Heron 2019), in Santa Clara, Utah, in Roggen, Colorado, and in Washington ( Mitchell 1936). With records north, west, and south of Montana, we predict this species is likely to occur at least along the western or southern borders of Montana, but we have not detected it so far.

Megachile (Megachiloides) wyomingensis Mitchell was recorded from badlands near Worland, Wyoming ( Mitchell1937a). It is also recorded from Sweetwater Co., Wyoming ( SEMC498031 ) and Leota, Utah ( BBSL519311 ), on Discover Life (01 June 2021). From these records, M. wyomingensis may possibly occur in the same area of south-central Montana, specifically south of Bridger , in the xeric landscape.

Further afield, but worth considering, specimens of Megachile (Chelostomoides) subexilis Cockerell are known from Fossil Butte National Monument, Wyoming (USGS_DRO314013), Timpanogos Cave National Monument, Utah (AMNH_BEE00079322), Provo, Utah (AMNH_BEE0007931), and Badlands National Park, South Dakota (USGS_DRO246767). This distribution suggests that this species is somewhat likely to occur in the badlands of south-central Montana near Bridger, the Black Hills region of Carter Co., and/or in the southwest corner of the state in or near the Centennial Valley (Beaverhead Co.).

Two introduced Eurasian species that may reach Montana. Megachile (Eutricharaea) pusilla Pérez is an invasive species originally from the Mediterranean region ( Ghazi-Soltani et al. 2017) that is expanding its range in the U.S., including the west (Discover Life 01 June 2021), with the closest records being in Otero and Yuma Counties of Colorado ( Scott et al. 2011) and in Timpanogos, Utah (AMNH_BEE00010214). Although not currently known from the state, M. pusilla could feasibly reach Montana as its range expands in the future.

One last invasive species to watch for is Megachile (Callomegachile) sculpturalis (Smith) . This native of eastern Asia is spreading from the eastern U.S. and now is established in most states east of the Mississippi River ( Stevens et al. 2019). The predicted range of this species includes far western Montana with a lower probability along the Yellowstone River Valley (loc. cit.) .