Microthereva Malloch

Webb, Donald W., 2006, The neotropical genera Microthereva Malloch and Peralia Malloch (Diptera: Therevidae: Therevinae), Zootaxa 1295, pp. 1-27 : 4-6

Microthereva Malloch

Microthereva Malloch (1932:244 desc., 245 key). Type species Microthereva argentiventris Malloch by original designation.

Diagnosis

Moderate sized flies, male body length 5.3–7.7 mm (n=15), female 6.5–9.8 mm (n=14).

Head. Ocellar tubercle dark reddish brown, not raised above level of vertex in males; setae dark brown, elongate. Eyes dark reddish brown, dichoptic; male ommatidia of equal size. Frons broad in both sexes, setae extending lateral to antennal base; black pruinescent band absent lateral to antennal base. Face projecting moderately beyond anterior margin of eyes. Antenna shorter than head length; scape cylindrical, longer than wide, greater than two times length of pedicel, subequal to width of flagellum, setae present medially on scape and pedicel, macrosetae dark reddish brown; pedicel globular, wider than long, setae dark brown, short; flagellum three segmented, first flagellomere oval, second flagellomere short, cylindrical, third flagellomere cylindrical, rounded apically, style spine­like, set in subapical cavity ( Fig. 1 ), flagellum over two times longer than wide, as long as scape. Parafacial setae elongate. Maxillary palpus cylindrical, apex rounded, greater than four times longer than wide. Gena lacking anterodorsal patch of short setae.

Thorax. Macrosetae 3–5 np, 2–3 sa, 1 pa, 1–4 dc, 2 sc. Vittae dark brown, dull. Postpronotal lobe concolorous with mesonotum. Cervical sclerite lacking setae and macrosetae. Prosternum lacking setae in and around central depression. Pleuron covered with pruinescence; setae elongate on propleuron, anepisternum, katepisternum, laterotergite, and scutellum; presence of setae variable on metanepisternum; absent on proepimeron and metakatepisternum. Wing. Length about three times longer than wide; pterostigma dark brown; setulae absent R1; cell m3 open widely; M1, M2, and M3 originate separately from apex of discal cell; cell cup closed, petiolate; anal angle broadly rounded; alula rounded. Legs. Coxae dark brown, pruinescence white, dense; setae white, elongate; setae absent on posterior area of midcoxa; hindcoxa with papillate anterior knob. Femora lacking appressed, lanceolate setae on dorsal surface; av 0:0:0–2 (generally 1), pv 0:0:0–1 (generally absent). Tibiae dark yellowish brown, apex of foretibia dark brown. Tarsi dark brown.

Abdomen. Male terminalia . Tergite 8 ( Figs. 2 , 11 ), anterior margin sinuate with sclerotized collar, posterior margin broadly emarginate; median length thick (> 0.05 mm); one pair of sensory sensillae. Sternite 8 ( Figs. 3 , 12 ) quadrate, anterior margin truncate; one pair of sensory sensillae. Epandrium ( Figs. 2 , 11 ) broad basally; shorter medially than wide; anterior margin emarginate; posterolateral margin short, not extending beyond cerci; lateral view rectangular. Cercus ( Figs. 2 , 11 ) free, oval; ending distal to posterolateral margin of epandrium. Hypoproct ( Figs. 2 , 11 ) ending distal to lateral margin of epandrium; apicoventral area flat. Hypandrium reduced, fused with anterior margin of gonocoxite. Gonocoxite ventral view ( Figs. 3 , 12 ) fused medially, sides rounded, posterolateral margin slightly tapered to broad point; inner gonocoxal process ( Figs. 3 , 12 ) sinuate, articulating with posterior margin of gonocoxite; gonocoxal apodeme ( Figs. 4 , 13 ) short, not extending beyond anterior margin of gonocoxite, gonocoxal bridge absent; ventral lobe large, fused medially, ventral setae short. Gonostylus lateral view ( Figs. 6 , 15 ) moderately broad, elongate, sinuate with two apical pointed projections; setae dark yellow. Aedeagus with ejaculatory apodeme ( Figs. 7 , 16 ) extending well beyond anterior margin of dorsal apodeme, anterior margin rounded, in cross­section flattened dorsoventrally; lateral ejaculatory processes not distinguishable. Female terminalia . Anterior margin of sternite 8 truncate; aedeagal guide narrow. Median lobe on tergite 9 lacking setae. Furca ( Figs. 10 , 19 ) quadrate, anterior and posterior margins closed; furcal projections absent. Common spermathecal duct shorter than furca, trifurcating anteriorly into two spermathecal ducts and a spermathecal sac. Spermathecal ducts narrow posteriorly before becoming threadlike and ending in an elliptical spermatheca. Immature Stages. Unknown.

Distribution

Microthereva is distributed in western Argentina and Chile ( Fig. 30 ).

Habitats and phenology

Microthereva has been collected from November to January.

Figures

FIGURES 1 – 10. Microthereva argentiventris. 1. Antenna. 2. Tergite 8, epandrium, cerci, hypoproct, dorsal view. 3. Sternite 8, gonocoxite, ventral view. 4. Gonocoxite, dorsal view. 5. Gonocoxite, lateral view. 6. Gonostylus, lateral view. 7. Aedeagus, dorsal view. 8. Aedeagus, ventral view. 9. Aedeagus, lateral view. 10. Female internal reproductive organs. Scale = 0.1 mm. Abbreviations: C = cercus, CD = common duct, DA = dorsal apodeme, Dp = distiphallus, EA = ejaculatory apodeme, Epa = epandrium, F = furca, Gs = gonostylus, Gx = gonocoxite, H = hypandrium, Hpt = hypoproct, Igp = inner gonocoxal process, Sp = spermatheca, Spd = spermathecal duct, SpS = spermathecal sac, SS = sensory seta, S 8 sternite 8, T 8 = tergite 8, VA = ventral apodeme, VL = ventral lobe.

FIGURES 11 – 19. Microthereva variventris. 11. Tergite 8, epandrium, cerci, hypoproct, dorsal view. 12. Sternite 8, gonocoxite, ventral view. 13. Gonocoxite, dorsal view. 14. Gonocoxite, lateral view. 15. Gonostylus, lateral view. 16. Aedeagus, dorsal view. 17. Aedeagus, ventral view. 18. Aedeagus, lateral view. 19. Female internal reproductive organs. Scale = 0.1 mm.

FIGURES 30 – 32. Distribution maps. 30. Microthereva argentiventris (closed circles), M. variventris (arrow). 31. Peralia hermanni. 32. Peralia vittata.