Sphecomyia dyari Shannon, 1925

M. Moran, Kevin & H. Skevington, Jeffrey, 2019, Revision of world Sphecomyia Latreille (Diptera, Syrphidae), ZooKeys 836, pp. 15-79 : 30-32

Sphecomyia dyari Shannon, 1925 Figs 2E, 7A, 8A, 9A, 21B, 25

Sphecomyia dyari Shannon 1925: 43 - Vockeroth 1965: 86; Stone et al. 1965: 612; Weisman 1965: 266, 1966a: 53, 1966b:196; Cole and Schlinger 1969: 331; Telford 1975: 21.

Type locality.

Gold Lake Camp, Plumas County, California. [USNM]

Diagnosis.

Can be confused with S. columbiana , S. cryptica sp. n., S. hoguei sp. n., S. oraria sp. n., and S. pattonii but can be distinguished by the following characters: Tergite 1 with uninterrupted, pruinose band along posterior margin. Scutellum mixed black and yellow pilose. Ventral calypter with long yellow pile. Sternites 2 to 4 with a posteromedial, triangular region of non-pruinosity on sternites 2 to 4 that is smaller on ensuing sternites. The species can only be distinguished from S. hoguei sp. n. by male genitalia in which the narrowest part of the surstylus is about one-fourth the width of base.

Redescription.

Male. Body length: 11.2-14.4 mm. Wing length: 9.1-10.6 mm. Head. Face yellow pruinose with shiny, black, medial vitta extending from oral margin to base of antenna; frons broad, about as long as broad at antenna, two-thirds as broad at vertex as at antenna, bare, with yellow pruinosity along posterior three-fourths; vertex triangular, longer than broad, shiny, with ocellar triangle black pilose; postocular border yellow pruinose; postocular and occipital pile yellow; male narrowly dichoptic; antenna black, black pilose, length of segments roughly in a 3:3:2 ratio.

Thorax. Copper shine; postpronotum, scutum and scutellum yellow pilose, except scutum with black pile posteromedially; postalar callus, proepimeron, posterior anepisternum yellow pilose; posterior katepisternum yellow pilose with broadly separated patches; anterior anepimeron yellow pilose; metasternum yellow pilose; postpronotum, anterior fourth of scutellum, broad posterior margin of anepisternum and dorso-posterior corner of katepisternum yellow pruinose; area between postpronota weakly yellow pruinose, except shiny medially; anepimeron shiny; scutum without pruinose vittae; ventral calypter with long yellow pile.

Legs. Foreleg black, except extreme apex of femur and anterior third of tibia reddish-yellow; fore tarsi slightly broadened; midleg reddish-yellow, except basal four-fifths of femur and last two tarsomeres black; hind leg reddish-yellow, except basal four-fifths of femur and last two tarsomeres black; legs yellow pilose, except fore tibia, fore tarsi, apex of fore femur and last two mid and hind tarsomeres black pilose; hind coxa yellow pruinose.

Wing. Hyaline; microtrichia absent from following areas: cell bc; cell r1 from base to about halfway to crossvein r-m; broad basal portion of cell br (before origin of M) and about basal two-fifths of narrower portion of this cell (caudad of spurious vein only); cell bm, except apex and narrow anterior and posterior margins of about apical fourth; broad anterior margin of cell cua; narrow, elongate, oval area proximal to vein A1.

Abdomen. Tergites and sternites shiny to sub-shiny, black with yellow pruinose markings as follows: tergite 1 pruinose along posterior margin; tergite 2 with broad, interrupted, truncate, medial band which meets a narrow, uninterrupted, posterior band in the posterolateral corners of tergite; tergite 3 with similar medial band, but more narrowly interrupted; pattern on tergite 4 same as tergite 3 except medial band very narrowly or incompletely interrupted; sternite 1 shiny; sternites 2 to 4 almost completely pruinose, with a triangular region of non-pruinosity posteromedially, with each ensuing region smaller; sternites 6 to 8 pruinose; abdominal pile yellow.

Male genitalia. Surstylus elongate, curving upward dorsally, more than three times as long as broad, about fourth the width of base at narrowest point; pile on dorsal surface of surstylus, symmetric in length; minute spines on ventral surface, with apical four-fifth of lateral inner surface also with spines; basal fourth of the ventral surface of the surstylus not produced into a lobe, but instead with slight invagination and no minute pubescence present; cerci with slight invagination on posterior border; aedeagus as in Fig. 2E.

Female.

Similar to male except normal sexual dimorphism.

Distribution.

U.S.A.: California, Oregon and Nevada (Fig. 25). Throughout the Sierra Nevada Mountains and Warner Mountains along with the portions of the Cascade Range, Klamath Mountains and the Northern Coast Ranges surrounding the Great Valley.

Biology.

Species collected visiting flowers Ceanothus cuneatus (Hook.) Nutt. and recorded leafsitting on Veratrum californicum Durand. Recorded flying mid-May through mid-August.