Megachile (Litomegachile) onobrychidis Cockerell, 1908

Bzdyk, Emily L., 2012, A revision of the Megachile subgenus Litomegachile Mitchell with an illustrated key and description of a new species (Hymenoptera, Megachilidae, Megachilini), ZooKeys 221, pp. 31-61 : 45-46

Megachile (Litomegachile) onobrychidis Cockerell, 1908

Megachile onobrychidis Cockerell, 1908: 266 Holotype male, USA: New Mexico (CAS).

Diagnosis.

The male Megachile onobrychidis is best distinguished from other species in this subgenus by the lack of a white tomentum on T6.The female Megachile onobrychidis resembles Megachile brevis , but with entirely black setae on S6 and apically on S5, and no pale appressed pubescence on T6.

Female. Body length9-12 mm. Mandible 4-toothed with no angulation on surface between teeth 3 and 4 (Figure 4A). T2-3 with deep transverse basal groove, T4 with shallow groove. T1-5 with apical fringes of white hair that covers marginal zone; T1-2 with thin or medially interrupted fringes of white hair, and white discal pubescence; T3-5 with black discal pubescence. T6 convex basally and concave apically in profile, and concave laterally in dorsal view; with erect setae basally and black appressed pubescence. S1-4 with ivory setae; S5 with black setae apically, ivory setae basally; S6 with black setae (Figure 5E).

Male. Body length7-9 mm. Mandible 3-toothed. Ocellocular distance equal to ocelloccipital distance (Figure 4D). T1-2 with white discal pubescence; T4-6 with white discal pubescence basally, black pubescence apically. Head and mesosoma with white pubescence (may appear yellow in early season specimens). T5 with complete fringe of white hair that covers marginal zone. T6 without tomentum, hairs sparse and discal surface clearly visible beneath (Figure 6H); transverse carina variable in shape, usually with indistinct medial notch and asymmetrical jagged projections; true apical margin with submedial teeth closer to lateral teeth than each other (Figure 6B). Genitalia and hidden sterna resemble those of Megachile brevis (Figures 7A1-A4).

Variability.

Male Megachile onobrychidis are separated from Megachile brevis in part by the lack of a tomentum on T6. Some specimens have no tomentum while others have sparse tomentum type hairs, but as long as these hairs are sparse enough so that the tergal surface is still visible, they are Megachile onobrychidis .

Distribution of material examined.

USA: Arizona: Cochise County (Aug.); California: Calaveras, Colusa Contra Costa, Humboldt, Imperial, Lake, Lassen, Los Angeles, Mendocino, Merced, Modoc, Monterey, Napa, Nevada, Orange, Placer, Plumas, Riverside, Sacramento, San Bernardino, Shasta, Siskiyou, Sonoma, Stanislaus, Tehama, Tuolumne, Tulare, Yolo and Yuba Counties (May-Oct.); Idaho: Canyon County (Aug.); Nevada: Churchill, Elko, Humboldt, Lyon and Washoe Counties (Jun.-Aug.); Oregon: Cassia and Jackson Counties (Jun.-Jul.); Utah: Cache and Wasatch Counties (Jun.-Aug.); MEXICO: Sinaloa, Sonora. 126 females, 193 males.

Flower records.

Asclepias speciosa ( Asclepiadaceae ), Calothamnus sp. ( Myrtaceae ), Clarkia biloba ( Onagraceae ), Clarkia dudleyana ( Onagraceae ), Clarkia unguiculata ( Onagraceae ), Dalea polydenia ( Fabaceae ), Daucus sp.( Apiaceae ), Grindelia camporum ( Asteraceae ), Lactuca pulchella ( Asteraceae ), Mentzelia sp. ( Loasaceae ), Phacelia sp. ( Hydrophyllaceae ), Polygonum aubertii ( Polygonaceae ).

Comments.

Mitchell (1935) listed this species as a subspecies of Megachile brevis . It was elevated to species level by Sheffield et al. (2011). It is a western North American species extending south to Sinaloa, Mexico. (Figure 13).