Osmia marginipennis Cresson, 1878

Osmia marginipennis Cresson, 1878: 106 [♂].

     Holotype ♂. USA, Colorado, by Morrison [ANSP no. 2548].

Osmia pascoensis Cockerell, 1897: 342 [♀]. Synonymy by Rust (1974: 63).

     Holotype ♀. USA, Washington, Pasco, 25 May 1896, by T. Kincaid [USNM no. 6869].

Osmia gaillardiae Cockerell, 1906: 227 [♀]. Synonymy by Sandhouse (1939: 31).

     Holotype ♀. USA, Colorado, Boulder, 6 July 1905, by W.P. Cockerell, on Gaillardia [USNM no. 29504].

Osmia viridior Cockerell, 1907: 361 [♂]. Synonymy by Sandhouse (1939: 31).

     Holotype ♂. USA, Colorado, Boulder, 20 May 1906, by S.A. Rohwer [USNM no. 27329].

Osmia leonis Cockerell, 1907: 123 [♀]. Synonymy by Sandhouse (1939: 31).

     Holotype ♀. USA, Colorado, Boulder, campus of University of Colorado, 8 May [no year provided], by E. Baker, on Taraxacum [USNM no. 28180].

Taxonomic Notes: Parker (1980) provided a full description of the ♀ and indicated how to separate it from that of O. californica Cresson, though as indicated for O. californica, scutum puncture density seems to be the most reliable way to distinguish them, with O. marginipennis having distint shiny interspaces medially. As indicated above, Rust (1974: 63) synonymized O. pascoensis Cockerell under O. californica Cresson (both described from the female), but Parker (1980: 39) believed this was in error, indicating that it was a synonym of O. marginipennis Cresson, though this has not been reflected in recent treatments.

Cockerell (1907:362) indicated that his O. viridior Cockerell was very similar to O. marginipennis Cresson, differing in the greener colouring of the mesothorax and scutellum, pale hair on the dorsal surface of the thorax, the shape of the apical margin of the clypeus (not subsinuate), and the more hyaline apical margin of the wings; Sandhouse (1939: 31) later recognized it as a synonymous.

DNA Barcode Index Number (BIN): BOLD:AAD6157

Biology: The nesting biology was studied by Parker (1980). Unlike other members of the subgenus Cephalosmia Sladen which nest in pre-existing burrows in wood (Rust 1974), females of O. marginipennis Cresson will build nests in both vertical and horizontal cracks in rock outcrops (Parker 1980). Like O. californica Cresson, this species uses a mixture of mud and masticated leaf material for builing nest plugs and partitions. Parker (1980) indicated that this species likely uses cohort splitting as a wintering strategy, with both adults and prepupae within a population wintering, a strategy similar to O. californica. Nest were parasitized by the cuckoo bee Stelis callura Cockerell, and the meloid beetle Tricrania stansburyi Haldeman (Parker 1980).

Distribution in Canada: Buckell 1950 [BC, and as O. pascoensis Cockerell]; Elwell 2012 [BC]; Sheffield and Heron 2019 [BC].