Orthonevra bellula (Williston, 1882)

Chrysogaster bellulus Williston 1882: 304 . Type-locality: USA, California (LT male USNM here designated).

Chrysogaster bellula . Williston 1887a: 36, figs (head, wing) (description), 1891: 7 (Mexico, Durango, Michocán, difference from nitida); Aldrich 1905: 348 (catalog citation); Kertész 1910: 31 (catalog citation); Fluke 1957: 49 (catalog citation).

Chrysogaster (Orthonevra) bellula . Sedman 1964: 170, figs (eye, mesonotum, wing) (key reference, descriptive note, distribution).

Orthonevra bellula . Thompson et al. 1976: 91 (catalog citation).

Figs 5 and 6

Differential diagnosis. Pile of the face long and scale-like (Fig. 5f); eye with sub-anterior vitta straight dorsally and sinuous ventrally, and middle straight vitta and complete fascia; scutum with 4 long more matte and darker vittae, without any other shorter vittate maculae laterally (Fig. 5b, e); wing with narrow faint dark vitta from end of R2+3 to R4+5, and on anterior half of M1; male surstyli symmetrical, with dorsal short triangular lobe and long ventral lobe.

Length. Body 5.73–6.41mm (n=3), wing 4.32–4.82mm (n=3); female 5.83–6.89mm (n=3), wing 4.53–5.44mm (n=3).

Distribution. USA (Washington to Idaho and South Dakota, south to California).

Comments. The lack of a lateral dark vittate macula on the scutum is unique among the species studied. The female genitalia are illustrated for the first time (Fig. 6). No map was generated for this species since it is restricted to the Nearctic region.

Material examined: USA. California, Vacaville, 1.x.1950, A.T. McClay (2 males CNC, CNC _ Diptera 91362– 3); Shasta, Shingleton, 2.vi.1941, P.D. Hurd (1 female CNC, CNC _ Diptera 91364); Walnut crk, ??.iii.????,? (1 male CNC, CNC _ Diptera 91359) ; Oregon, Medford, 5.ix.1950, A.T. McClay (1 female CNC, CNC _ Diptera 91366) ; Utah, Devil’s Kitchen, 14.viii.1943, G.F. Knowlton & D.R. Maddock (2 males CNC, CNC _ Diptera 91358, …91361); Moab, 8.v.1941, G.F. Knowlton & F.C. Harmston (1 female CNC, CNC _ Diptera 91365); Promontory, 5.x.1942, G.F. Knowlton & W.E. Peay (1 male CNC, CNC _ Diptera 91360) .