Spiriverpa Irwin and Lyneborg

Webb, Donald W., 2005, A revision of the Holarctic genus Spiriverpa Irwin and Lyneborg (Diptera: Therevidae: Therevinae), Zootaxa 816, pp. 1-56 : 9-10

Spiriverpa Irwin and Lyneborg

Spiriverpa Irwin and Lyneborg (1981a:214 orig. desc.; 1981b:522 key), Lyneborg (1989:24 cat.), Nagatomi and Lyneborg (1989:359 add. desc.). Type species Thereva lunulata Zetterstedt (1838:523) , by original designation. Type locality: Norway (Lapponia, Norvegica). Spiriverba: Zaitzev (1986:4, misspelling of Spiriverpa ).

Irwin and Lyneborg (1981a:214) provided an extensive description of this genus. The following are additions to the description of Irwin and Lyneborg.

Moderate sized flies, male (6.8–11.5 mm, n=54), female (6.8–12.2 mm, n=55).

Head. Ocellar tubercle reddish brown, pruinescence gray; setae dark brown to black. Eyes reddish brown. Frons lacking black pruinescent band lateral to antennal base. Antenna generally shorter than length of head; scape cylindrical, longer than wide, longer than length of pedicel; pedicel globose, wider than long; flagellum longer than wide, subequal to or longer than length of scape, first flagellomere oval, distal third tapered apically, second flagellomere short, cylindrical, third flagellomere short, tapering to point apically, apical style minute. Parafacial broad, pruinescence white to silver. Maxillary palpus cylindrical, apex rounded, longer than wide. Genal setae white. Occiput convex, pruinescence white, dense; setae white, elongate over entire occiput; macrosetae dark reddish brown to black. Postocular macrosetae dark reddish brown to black, in single row.

Thorax. Macrosetae males 2–4 np, 1–2 sa, 1 pa, 1–2 dc, 2 sc (n=54), females 2–5 np, 1–2 sa, 1 pa, 1–3 dc, 2 sc (n=55). Mesonotum dark brown to black, pruinescence gray. Postpronotal lobe concolorous with mesonotum. Pleuron and scutellum pruinescence gray, dense. Setae on posterodorsal corner of proepimeron, over entire anepisternum, laterotergite, metanepisternum, and scutellum, on anterior half of katepisternum, across dorsal margin of anepimeron; absent on anepimeron, meron, and metakatepisternum. Wing. Pterostigma brown; setulae absent on R1; cell cup closed, petiolate. Legs. Coxa dark reddish brown, pruinescence gray, dense; hindcoxa with pale yellow papillate projection; apical macrosetae dark brown. Femoral setae white, filiform ventrally on fore­ and midfemora, white, lanceolate, appressed on dorsal surface of femora. Abdomen. Male terminalia . Gonocoxite separated medially, broadly rounded laterally, tapered posterolaterally; gonocoxal apodeme reduced, not extending beyond anterior margin of gonocoxite. Gonostylus curved dorsally; setae pale yellow on dorsal and ventral surfaces. Aedeagus with dorsal apodeme triangular, sclerotized anterior margin deeply emarginate; ejaculatory apodeme with anterior third broadly clavate, extending beyond anterior margin of dorsal apodeme. Lateral ejaculatory processes reniform, separated medially. Female terminalia . Tergite 8 quadrate with broad truncated anteromedial projection, posterior margin truncate. Sternite 8 dark brown, quadrate, about 1.5 times longer than wide, posterior fourth tapered to broad apical point, posterior margin emarginate medially, aedeagal guide elongate, tapered anteriorly; setae abundant posteromedially. Median lobe of tergite 9 with setae (absent only in S. bella ). Cerci ovate. Furca with anterior margin closed, anterolateral projection short; posteromedial and anteromedial projections absent. Spermathecal sac about 1.5 times longer than wide; spermathecal ducts narrow leading to 2 oval spermatheca.

Immature stages. The immature stages of Spiriverpa senex have been reared but not described.

Biology. Spiriverpa is primarily boreal in its distribution having been handnetted, sweepnetted or collected in Malaise traps in sandy areas amongst jack pine, in old fields, second growth forest, red maple swamps, cutover sugar maple woods, in poison sumac swamps, in dry mixed forests, in fens, or on Cornus sp., Pinus sp., and Solidago sp. and in alfalfa and red clover fields. Spiriverpa albiceps has also been handnetted or collected in Malaise traps on beaches and sand dunes or in yellow pan traps set in dunes amongst Equisetum sp. Larvae of Spiriverpa senex have been sieved from compost and muck soil and from a cabbage and raspberry patch. Spiriverpa albiceps , S. argentata , S. bella , S. lunulata , and S. senex have summertime flight activity, although S. senex does fly from November through January. Spiriverpa cinerascens has the broadest flight activity extending from January through September.