Osmia californica Cresson, 1864

Osmia californica Cresson, 1864: 24 [♀].

     Holotype ♀. USA, California, Fort Crook, by H. Ulke [ANSP no. 2514].

Osmia nassa Cockerell, 1910: 272 [♀]. Synonymy by Sandhouse (1939: 31).

     Holotype ♀. USA, California, Claremont, by Baker [USNM no. 13439].

Osmia occidentalis Michener, 1936: 42 [♀]. Synonymy by Sandhouse (1939: 31).

     Holotype ♀. USA, California, Mono County, Gull Lake, 11 July 1934, by J.E. Law [].

Taxonomic Notes: The ♂ was described by Rust (1974: 64).

Michener (1936: 42) indicated the similarity of his O. occidentalis Michener to both O. pascoensis Cockerell and O. nassa Cockerell, with only subtle differences in robustness and hair colour to the former, and puncture density and hair colour in the latter.

Though Sandhouse (1939: 22) distinguished female O. californica Cresson (and O. pascoensis Cockerell) from O. marginipennis Cresson based on clypeal puncture density (i.e., more sparse in the latter), Rust (1974: 71) indicated that the females of O. californica and O. marginipennis were indistiguishable. Rust (1974: 63) also synonymized O. pascoensis Cockerell under O. californica Cresson (both described from the female), but Parker (1980: 39) believed this was in error, indicating that O. pascoensis was a synonym of O. marginipennis Cresson. Parker (1980) distinguished O. marginipennis from O. californica mainly by hair colour, indicating all pale on tergum 1 (which does not always seem to be the case, as the basolateral area often have black hair in both species) and the more sparsely punctate medial area of the scutum in the former, which seems to be supported by COI.

DNA Barcode Index Number (BIN): BOLD:AAA7671

Biology: Several aspects of the nesting biology of this species were studied or summarized by Levin (1966), Rust (1974), and Torchio (1989a), who indicated that this species was unusual compared to other North American Osmia in that it used both mud and masticated plant material, as a mixture, for nest plug and partition construction, not one or the other, though Parker (1980) also reported this for O. marginipennis. Parker (1980) indicated that this species uses cohort splitting as a wintering strategy, with both adults and prepupae within a population wintering, a strategy similar to O. marginipennis. Cripps and Rust (1989) indiacted that this species was a Asteraceae specialist. Torchio (1989b) indicated that Stelis montana Cresson is a nest parasite.

Distribution in Canada: Criddle et al. 1924 [BC]; Sandhouse 1939 [BC]; Buckell 1950 [BC]; Rust 1974 [BC]; Elwell 2012 [BC]; Sheffield and Heron 2019 [BC].