Entesia Oldroyd

Winterton, Shaun L. & Irwin, Michael E., 2023, Revision of the South American stiletto fly genera Entesia Oldroyd and Melanothereva Malloch, with the description of a new genus (Therevidae: Agapophytinae), Zootaxa 5269 (1), pp. 1-82 : 5-7

Entesia Oldroyd

Entesia Oldroyd, 1968: 377 — Metz & Irwin (2000: 985 [key]); Metz et al. (2003: 253); Winterton (2006: 18); Holston et al. (2007: 282 [phylogeny]); Gaimari & Webb (2009: 636 [key]); Winterton et al. (2016: 151 [phylogeny]); Irwin & Winterton (2020: 276; 2021: 273).

Type species: Entesia tarsata Oldroyd, 1968: 378 , by original designation.

Diagnosis. Medium-sized, slender, yellow to brown flies; antenna shorter than, or subequal to head length; scape subequal to flagellum length, usually narrow and cylindrical; parafacial setae absent; male sometimes with additional macrosetae scattered on occiput; palpus slender; cervical sclerite sometimes with one or more macrosetae on lateral lobe; prosternum medial pile present or absent; 1 or 2 pairs of scutellar macrosetae; wing cell m 3 open; hind femur with subapical anteroventral macroseta (rarely absent); male abdominal sternite 8 with paired secondary sclerites along posterior margin.

Redescription. Head. Dimensions in profile higher than long, to subequal; antennae positioned on lower half of head and directed anteriorly, usually shorter than head (rarely same length); flagellum cone-shaped to cylindrical, slightly tapered distally, subequal to or shorter than combined scape and pedicel length; scape cylindrical, length usually less than 3x pedicel length (rarely longer), slightly wider than other segments and with macrosetae variable; frons flat, grey or brown pubescent, sometimes with setae; male frons width (at narrowest point) variable, ranging from eyes being contiguous to width equal to ocellar tubercle; parafacial without setae; face flat; gena rounded; mouthparts short, palpus slender; male postocular macrosetae length variable, sometimes elongate and recurved; male occiput sometimes with additional macrosetae scattered medially. Thorax. Medial furrow of prosternum with or without setae; lateral lobe of cervical sclerite sometimes with one or more macrosetae; pleuron overlain with dense silver, brown or grey pubescence; metanepisternum without setae; scutum with filiform setae, often of variable length; scutal chaetotaxy (pairs of macrosetae): notopleural (np): 3–6; supra alar (sa), 1; post alar (pa), 1; dorsocentral (dc), 2–6; scutellar (sc) 1–2; wing infuscation and markings variable, including hyaline, dark along wing veins to uniformly smoky infuscate, sometimes opaque white with brown mottled pattern; wing membrane uniformly covered with microtrichia; vein R 2+3 shape a gradual sigmoid curve; vein R 1 with setae absent; cell m 3 open, veins M 3 and M 4 separate to margin; posterior surfaces of mid- and hind coxae usually without setae; hind coxal knob present; femoral velutum patches absent; macrosetae absent on fore- and midfemora, hind femur with anteroventral (av) seta usually present subapically; leg length variable, femora and tibiae approximately equal in length across all legs, hind leg sometimes distinctly longer and thicker than fore and mid legs. Abdomen. Shape in basal half distinctly tapered from base; tergite 2 usually with a concentrated patch of shortened setae posteromedially. Terminalia. Male gonocoxites with velutum patches absent, halves separate medially, rarely fused, posterior outer gonocoxal process well developed; inner gonocoxal process well developed and articulated; ventral lobe usually at least half length of gonostylus; phallus with dorsal apodeme of parameral sheath ‘T’-shaped or triangular, distiphallus shape variable, ventral apodeme forked. Female with spermathecal sac as a single lobe with three spermathecae joining common spermathecal sac duct close to bursa ( Fig. 30 ); sternite 8 emarginate posteromedially; acanthophorite macrosetae with two sets A1 enlarged; tergite 8 elongate with broad anteromedial process.

Included species. Entesia blackmani ( Oldroyd, 1968) , E. delicata sp. n., E. dolichochele sp. n., E. glauca sp. n., E. guttata sp. n., E. hyalina sp. n., E. lurida sp. n., E. maculicornis ( Jaennicke, 1867) (= Psilocephala leptiformis Kröber, 1928a syn. n.), E. notabilis ( Macquart, 1841a) (= Psilocephala fuzi Kröber, 1928a syn. n.), E. pallidiventris ( Malloch, 1932) , E. pallidiventroides sp. n., E. penai sp. n., E. rubida ( Wulp, 1888) (= Entesia tarsata Oldroyd, 1968 syn. n.), E. rubidaster sp. n. and E. tessera sp. n. Several undescribed species are known in collections but are not described herein as they are damaged specimens.

Distribution. South America: Argentina, Chile.

Comments. Entesia was erected for E. tarsata and diagnosed by the slender appearance, pale colouration and the long and swollen basitarsus of the hind leg. The characters that separate Entesia and Melanothereva overlap considerably, with numerous species exhibiting characters diagnostic of both genera, as well as intermediate states. A good example of the composite nature of species in both these genera is E. blackmani , which was originally described by Oldroyd (1968) in Melanothereva in the same paper he described Entesia . Moreover, in footnotes, Malloch (1932: 249–250) quoted contemporaneous annotations by F.W. Edwards on specimens in the Bigot collection, which were determined as E. notabilis but noting their striking similarity to Melanothereva in all but colouration. Three synonyms are identified here, including E. rubida ( Wulp, 1888) (= Entesia tarsata Oldroyd, 1968 syn. n.), E. notabilis ( Macquart, 1841a) (= Psilocephala fuzi Kröber, 1928a syn. n.) and E. maculicornis ( Jaennicke, 1867) (= Psilocephala leptiformis Kröber, 1928a syn. n.).

Key to species of Entesia

1. Scutellum with two pairs of macrosetae.................................................................... 2.

- Scutellum with a single pair of macrosetae................................................................. 7.

2. Abdomen with anteromedial tuft of erect setae on sternite 1.................................................... 3.

- Abdomen without anteromedial tuft of setae on sternite 1...................................................... 5.

3. Male with only a single row of postocular macrosetae; postocular macrosetae a mixture of black and yellow in both sexes; four or fewer pairs of scutal dorsocentral macrosetae; black setae on frons and scape few in number (frequently absent on frons), relatively short; two rows of setae along costa ( Figs 19–21 )............................. Entesia notabilis (Macquart) .

- Male with macrosetae scattered on occiput in addition to row of elongate postocular macrosetae, macrosetae uniformly black in both sexes; more than four pairs of scutal dorsocentral macrosetae; numerous, relatively elongate black setae on frons and scape; more than two rows of setae along costa.............................................................. 4.

4. Head and body covered with brownish-tan pubescence ( Figs 8 , 9 )............................... Entesia glauca sp. n.

- Head and body covered with grey pubescence (female unknown) ( Fig. 24 )................ Entesia pallidiventroides sp. n.

5. Male with single row of postocular macrosetae; prosternum without setae medially; male with sparse, silver velutum pubescence on abdomen (female unknown) ( Fig. 14 ).................................................. Entesia hyalina sp. n.

- Male with macrosetae scattered on occiput in addition to row of elongate postocular macrosetae; prosternum with setae medially; male abdomen with silver velutum pubescence present or absent........................................ 6.

6. Posterior surfaces of mid- and hind femora with setae; male eyes almost contiguous below ocellar tubercle; postocular macrosetae black, occipital macrosetae pale; cervical sclerite with one or more macrosetae laterally; male abdomen without silver velutum pubescence ( Figs 1–3 ).............................................. Entesia blackmani (Oldroyd) .

- Posterior surfaces of mid- and hind femora without setae; male eyes separated by distance equal to width of ocellar tubercle; postocular and occipital macrosetae black; cervical sclerite without macrosetae; male abdomen with silver velutum pubescence ( Fig. 23 )................................................................... Entesia pallidiventris (Malloch) .

7. Flagellum elongate and only slightly tapered ( Figs 31 , 32 ).................................. Entesia rubidaster sp. n.

- Flagellum relatively short and conical to elliptical........................................................... 8.

8. Diminutive species; frons and parafacial with two pairs of glabrous spots free of pubescence (barely evident in male); all femora relatively equal in length ( Figs 34–36 ).............................................. Entesia tessera sp. n.

- Size variable; frons and parafacial lacking glabrous areas free of pubescence; hind femora distinctly longer than fore- and midfemora........................................................................................... 9.

9. Prosternum with setae present medially; abdomen brownish grey with distinct double vittae laterally along abdomen ( Figs 17 , 18 )...................................................................... Entesia maculicornis (Jaennicke) .

- Prosternum lacking setae; abdomen otherwise marked and lacking lateral double vittae............................. 10.

10. Wing membrane translucent to opaque, milky white with extensive speckling of fine dark spots (faded in some specimens); venation brownish, darker at corners of wing cells; abdomen typically orange to dark yellow, thorax with brown and silver pubescence; setae on body white; abdominal tergite 2 lacking patch of short setae posteromedially.................... 11.

- Wing otherwise, typically hyaline, mottled or smoky brown, never white with fine speckled spots; venation uniform brownish; abdomen and thorax variable; setae on body usually dark, sometimes white; abdominal tergite 2 with patch of shorter setae posteromedially..................................................................................... 12.

11. Male frons silver in lower half and brown in upper half, brown band delimiting different areas; male eyes separated below ocellar tubercle by distance slightly wider than width of anterior ocellus; female frons silver with extensive brown suffusion dorsally ( Figs 10 , 11 )................................................................. Entesia guttata sp. n.

- Male frons silver with faint brown suffusion dorsally, lacking brown band midway; male eyes separated below ocellar tubercle by distance less than width of anterior ocellus; female frons predominantly silver with only faint brown suffusion medially ( Figs 5–7 )...................................................................... Entesia dolichochele sp. n.

12. Male.............................................................................................. 13.

- Female........................................................................................... 16.*

13. Frons with eyes separated below ocellar tubercle by distance slightly greater than width of anterior ocellus; occiput slightly rounded convex ( Fig. 25 )................................................................ Entesia penai sp. n.

- Frons with eyes either contiguous below ocellar tubercle or separated by distance less than width of anterior ocellus; occiput distinctly flat or slightly concave........................................................................ 14.

14. Abdomen yellowish-brown with at most, a faint brown marking medially on tergites 3–6 ( Fig. 4 )..... Entesia delicata sp. n.

- Abdomen mostly or entirely dark brown.................................................................. 15.

15. Frons with distinct brown spot medially; abdomen uniformly dark brown ( Fig. 28 )............... Entesia rubida (Wulp) .

- Frons uniformly silver; abdomen dark brown, cream-white posteriorly and on intersegmental membrane of tergites 2–4 ( Fig. 16 )................................................................................. Entesia lurida sp. n.

16. Female abdomen dark brown, cream-white posteriorly and on intersegmental membrane of tergites 2–4, lacking narrow dark marking medially on posterior tergites ( Fig. 15 )............................................. Entesia lurida sp. n.

- Female abdomen mostly dark yellow to orange, often with narrow dark marking medially on posterior tergites.......... 17.

17. Frons with dark brown spot medially above antennal bases ( Fig. 27 )........................... Entesia rubida (Wulp) .

- Frons uniform silver to grey, lacking dark spots above antennal bases ( Fig. 25 )..................... Entesia penai sp. n.

*Note: the female of E. delicata sp. n. is unknown.

Figures

FIGURE 1. Entesia blackmani (Oldroyd): A. Male, oblique view; B. same, lateral view.

FIGURE 2. Entesia blackmani (Oldroyd): A. Female, oblique view; B. same, lateral view.

FIGURE 3. Entesia spp.: A. Entesia blackmani (Oldroyd), male, close-up of coxae; B. Entesia glauca sp. n., male, close up of head and sternum.

FIGURE 4. Entesia delicata sp. n.: A. Male, oblique view; B. same, lateral view.

FIGURE 5. Entesia dolichochele sp. n.: A. Male, oblique view; B. same, lateral view.

FIGURE 6. Entesia dolichochele sp. n.: A. Female, oblique view; B. same, lateral view.

FIGURE 7. Entesia dolichochele sp. n.: A. Male head and thorax, anterior view; B. same, oblique view (Scale line: 0.5 mm).

FIGURE 8. Entesia glauca sp. n.: A. Male, oblique view; B. same, lateral view.

FIGURE 9. Entesia glauca sp. n.: A. Female, anterolateral view.

FIGURE 10. Entesia guttata sp. n.: A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 11. Entesia guttata sp. n.: A. Female, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 14. Entesia hyalina sp. n.: A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 15. Entesia lurida sp. n.: A. Male, oblique view; B. same, lateral view.

FIGURE 16. Entesia lurida sp. n.: A. Female, oblique view; B. same, lateral view.

FIGURE 17. Entesia maculicornis (Jaennicke): A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 18. Entesia maculicornis (Jaennicke): A. Female, oblique view; B. same, lateral view.

FIGURE 19. Entesia notabilis (Macquart): A. Male, oblique view; B. same, lateral view.

FIGURE 20. Entesia notabilis (Macquart): A. Female, oblique view; B. same, lateral view.

FIGURE 21. Entesia notabilis (Macquart): A. Male head, anterior view; B. male, abdomen, dorsal view.

FIGURE 23. Entesia pallidiventris (Malloch): A. Male, oblique view; B. same, lateral view.

FIGURE 24. Entesia pallidiventoides sp. n.: A. Male, oblique view; B. same, lateral view.

FIGURE 25. Entesia penai sp. n.: A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 27. Entesia rubida (Wulp): A. Male, oblique view; B. same, lateral view.

FIGURE 28. Entesia rubida (Wulp): A. Female, oblique view; B. same, lateral view.

FIGURE 30. Entesia rubida (Wulp), female internal genitalia.Abbreviations: ss, spermathecal sac; ssd, spermathecal sac duct; s, spermatheca; f, furca; ag, accessory gland. Scale line: 0.2 mm.

FIGURE 31. Entesia rubidaster sp. n.: A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 32. Entesia rubidaster sp. n.: A. Female, oblique view; B. same, lateral view.

FIGURE 34. Entesia tessera sp. n.: A. Male, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 35. Entesia tessera sp. n.: A. Female, oblique view; B. same, lateral view (Scale line: 1.0 mm).

FIGURE 36. Entesia tessera sp. n.: A. Male head, anterolateral view; B. female head, oblique view.