Therevinae

Irwin, Michael E. & Winterton, Shaun L., 2020, A new genus of therevine stiletto flies from South America (Diptera: Therevidae), Zootaxa 4838 (1), pp. 52-70 : 53-54

Key to genera of Therevinae of the Neotropical Region

New information on the morphology of various genera, as well as the inclusion of Dasythereva gen. n. has rendered previous keys to Neotropical Therevinae unworkable. This revised key is based originally on those keys by Irwin & Lyneborg (1981), Gaimari & Irwin (2000), Metz & Irwin (2000) and Gaimari & Webb (2009), but is heavily modified and restructured to accommodate new information and corrections. Representatives of all genera were examined here except for Winthemmyia Webb , which was unavailable and its inclusion is based on information provided in the original description by Webb (2005).

1. Femora with erect, filiform setae only, length variable; occiput broadly rounded with multiple rows of postocular macrosetae in both sexes with minimal sexual dimorphism.............................................................. 2.

- Femora with erect, filiform setae admixed with adpressed, lanceolate (scale-like) setae; occiput variable, frequently flat and rarely broadly rounded in males, males usually with distinctly fewer postocular macrosetae than female (often just a single row dorsally)............................................................................................ 3.

2. Parafacial setae present; flagellum with subapical style............................... Microthereva Malloch (2 spp.).

- Parafacial setae absent; flagellum with apical style........................................ Peralia Malloch (2 spp.).

3. Wing vein R 1 with macrosetae on dorsal surface in apical half of wing................... Protothereva Malloch (3 spp.).

- Wing vein R 1 lacking macrosetae in apical half of wing....................................................... 4.

4. Prosternum without setal pile medially.................................................................... 5.

- Prosternum with setal pile medially....................................................................... 9.

5. Post-spiracular setae absent on metanepisternum; male genitalia with gonocoxites separate medially; inner gonocoxal apodeme well developed and articulated....................................................... Lindneria Kröber (8 spp.).

- Post-spiracular setae present on metanepisternum; male genitalia with gonocoxites fused medially; inner gonocoxal apodeme absent or greatly reduced, not-articulated.................................................................. 6.

6. Thorax covered with grey-silver pubescence; wing mostly hyaline.............................................. 7.

- Thorax with distinct areas lacking pubescence, pubescence frequently dark coloured and matte; wing usually with markings ranging from uniformly infuscate to well-delineated distal banding.............................................. 8.

7. Male aedeagus with large subapical flanges........................................... Ptilotophallos Webb (1 sp.).

- Male aedeagus narrow without large subapical flanges....................... Anolinga Gaimari & Irwin [part] (2 spp.).

8. Gena produced anteroventrally below eye; setae on pleuron, coxae and abdominal tergite 1 white; body with matte black pubescence, when present, typically limited to frons, scutum and/or scutellum................ Cerocatus Rondani (30 spp.).

- Gena rounded, not produced below eye; setae on pleuron, coxae and abdominal tergite 1 black; body covered extensively with matte black pubescence...................................................... Coleiana Gaimari & Irwin (1 sp.).

9. Face with pair of glossy black calli below antennae.................................... Chromolepida Cole (5 spp.).

- Face lacking pair of glossy black calli below antennae....................................................... 10.

10. Head and body with extensive pile of white scale-like setae; male frons wide, eyes separated by distance wider than ocellar tubercle; tibial and tarsal macrosetae relatively elongated..................................................... 11.

- Head and body with variable setal pile, but setae not predominantly white and scale-like; male frons narrow, eyes contiguous of barely wider than width of medial ocellus; tibial and tarsal macrosetae regular, not elongated...................... 12.

11. Elongate, diminutive species (body length usually <8.0 mm); parafacial setae absent; frons with very few setae; wing cell m 3 closed; scale-like setae covering body adpressed, sparse; leg macrosetae usually white.... Argolepida Metz & Irwin (1 sp.).

- Large, robust species (body length usually> 10.0 mm); parafacial setae present; frons with extensive setal pile; wing cell m 3 open; scale-like setae covering body erect, dense, giving a woolly appearance; leg macrosetae black ( Figs 1–7 )......................................................................................... Dasythereva gen. n. (2 spp.).

12. Thorax with metakatepisternum with a patch of setae...................................... Elcaribe Webb (14 spp.).

- Thorax with metakatepisternum lacking setae.............................................................. 13.

13. Antennal scape enlarged and bulbous, noticeably thicker than pedicel and flagellum; male frons and parafacial with extensive setal pile; male frons as wide as, or slightly wider than, median ocellus at narrowest point........................... 14.

- Antennal scape at most only slightly thicker than pedicel and flagellum; male frontal setal pile variable, (ranging from absent to extensive); parafacial typically lacking setal pile (present in some species of Ozodiceromyia and Notiothereva ); male frons narrower than median ocellus at narrowest point, frequently contiguous......................................... 15.

14. Tuft of pale setae anterior to dark setae on basal lobe of costal vein; male frons slightly narrower than median ocellus; posterior surface of midcoxa without setal pile; male genitalia with gonocoxites fused medially, inner gonocoxal apodemes absent.................................................................................... Breviperna Irwin (1 sp.).

- Setae at base of costal vein uniformly small and dark; male frons slightly wider than median ocellus; posterior surface of midcoxa with a few setae present; male genitalia with gonocoxites separated medially, inner gonocoxal apodemes present................................................................................ Amplisegmentum Webb (1 sp.).

15. Midcoxa with setal pile present on posterior surface (sometimes just a few setae).................................. 16.

- Midcoxa lacking setal pile on posterior surface............................................................. 22.

16. Cervical sclerite with distinct black macroseta directed ventrolaterally............. Megalinga Irwin & Lyneborg (2 spp.).

- Cervical sclerite lacking black macroseta................................................................. 17.

17. Wing cell m 3 open to wing margin; metanepisternum lacking postspiracular setae.................................. 18.

- Wing cell m 3 open or closed; metanepisternum with patch of postspiracular setae.................................. 19.

18. Scutum with dorsocentral macrosetae absent; forefemur with posteroventral (pv) macrosetae lacking, midfemur with anteroventral (av) macrosetae lacking; male aedeagus with a broad distiphallus with flanking processes; gonocoxite with inner gonocoxal process present............................................................ Winthemmyia Webb (1 sp.).

- Scutum with dorsocentral macrosetae present; fore- and midfemora with av and pv macrosetae present; male aedeagus with a narrow distiphallus; gonocoxite with inner gonocoxal process absent............. Rhagioforma Irwin & Lyneborg (2 sp.).

19. Parafacial setae present or absent; male gonocoxites with 2–3 posteriorly directed setae (distinctly larger than surrounding setae); inner gonocoxal process present........................................ Notiothereva Metz & Irwin (6 spp.).

- Parafacial setae always absent; all setae on gonocoxites uniform in size; inner gonocoxal process absent............... 20.

20. Male aedeagus with distinct subapical hood on the distiphallus; gonocoxites with ventral lobe relatively small; female genitalia with furca with posteriorly directed medial process on anterior bridging arm........ Lysilinga Irwin & Lyneborg (10 spp.).

- Male aedeagus lacking dorsal processes the distiphallus; gonocoxites with ventral lobe relatively large and curved around base of gonostylus; female genitalia with furca without medial process on anterior bridging arm.......................... 21.

21. Male gonocoxites with extensive ventrally directed setae along ventromedial surface; female frons with glossy black area free of pubescence............................................................. Nigranitida Metz & Irwin (4 spp.).

- Male gonocoxites sometimes with extensive ventrally directed setae present or absent; female frons usually entirely pubescent................................................................ Brachylinga Irwin & Lyneborg (24 spp.).

22. Metanepisternum lacking postspiracular setae; wing cell m 3 open; male gonocoxites separate medially, hypandrium distinct; inner gonocoxal process present (sometimes highly modified)................................................. 23.

- Metanepisternum with patch of postspiracular setae; wing cell m 3 open or closed; male gonocoxites fused medially, hypandrium frequently not discernible; inner gonocoxal process absent.................................................... 26.

23. Single pair of scutellar macrosetae; male genitalia with inner gonocoxal process highly modified; aedeagus with angular processes flanking distiphallus, parameral sheath frequently with numerous spines..... Penniverpa Irwin & Lyneborg (14 spp.).

- Two pairs of scutellar macrosetae; male genitalia with inner gonocoxal process elongate and not modified; aedeagus lacking angular processes flanking distiphallus, parameral sheath lacking spines......................................... 24.

24. Dorsocentral macrosetae absent............................................... Insulatitan Metz & Irwin (4 spp.).

- Dorsocentral macrosetae present........................................................................ 25.

25. Male abdomen with silver pubescence posterolaterally on tergites 2–6, brown medially; wing and legs not noticeably elongated; all femora approximately equal in length and not distinctly longer than respective tibial segment of each leg; male genitalia with gonocoxite with outer gonocoxal process present, all setae on gonocoxite uniform in size; female tergite 8 elongate and quadrangular, acanthophorite with two sets of regular spines (A1 and A2)............... Distostylus Metz & Webb (1 sp.).

- Male abdomen almost entirely overlain with dense silver velutum pubescence; wing and legs relatively elongate; hind femur noticeably longer than fore- and midfemora, all femora distinctly longer than respective tibial segment of each leg; male genitalia with gonocoxite with outer gonocoxal process absent, 2–3 large posteriorly directed macrosetae on posterolateral corner; female tergite 8 narrow and ‘T’-shaped, acanthophorite with single set of poorly-developed A1 acanthophorite spines, A2 spines barely distinguishable from regular setae........................................ Apenniverpa Webb (1 sp.).

26. Wing cell m 3 open; male aedeagus with irregularly spiral-shaped distiphallus.................... Spiracolis Webb (1 sp.).

- Wing cell m 3 closed; male aedeagus with straight or curved distiphallus, but not irregularly spiral-shaped............... 27.

27. Frons and thorax with distinct areas lacking pubescence that are usually black and glossy, pleuron with vertical band lacking pubescence from wing base through meron; gena produced ventrally with patch of dark setae; parafacial setae sometimes present......................................................................... Ozodiceromyia Bigot (29 spp.).

- Frons and thorax uniformly covered with grey-silver to brownish pubescence; gena rounded, lacking dark setal patch; parafacial without setae.................................................................................... 28.

28. Male occiput with two distinct rows of postocular macrosetae (second row sometimes irregular); one pair of dorsocentral macrosetae; male gonocoxite with narrow posteriorly directed process ventrally on gonocoxite.................................................................................................. Nesonana Gaimari & Irwin (2 spp.).

- Male occiput with single distinct row of postocular macrosetae; two pairs of dorsocentral macrosetae; male gonocoxite without posteriorly directed process ventrally on gonocoxite......................... Anolinga Gaimari & Irwin [part] (2 spp.).

Figures

FIGURE 1. Dasythereva penai sp. n., adult male, lateral view. Body length: 9.5 mm.

FIGURE 2. Dasythereva penai sp. n., adult male, oblique view. Body length: 9.5 mm.

FIGURE 3. Dasythereva penai sp. n., adult female, lateral view. Body length: 9.2 mm.

FIGURE 4. Dasythereva penai sp. n., adult female, oblique view. Body length: 9.2 mm.

FIGURE 5. Dasythereva gen. n., adult males, anterior view. A. D. penai sp. n.; B. D. patagonia sp. n.

FIGURE 6. Dasythereva gen. n., adult males, dorsal view. A. D. penai sp. n., body length: 9.5 mm; B. D. patagonia sp. n., body length: 9.0 mm.

FIGURE 7. Dasythereva patagonia sp. n., adult male, lateral view. Body length: 9.0 mm.