Key to Macrurohelea of the Neotropical region

(females of M. similis Spinelli & Grogan, M. morenoi n. sp. and M. ventanensis n. sp., and the males of M. fuscipennis Spinelli & Grogan and M. wirthi Spinelli & Grogan are unknown)

1. Females............................................................................................. 2

- Males............................................................................................. 15

2. One spermatheca......................................................................................3

- Two spermathecae (Figs. 4, 11, 29)....................................................................... 4

3. Large species (wing length 2.05 mm); wing with intercalary vein in cell r 3; wing membrane infuscated, veins dark brown............................................................................. M. monotheca Spinelli & Grogan

- Medium-size species (wing length 1.59–1.74 mm); wing without intercalary vein in cell r 3; wing membrane hyaline, veins pale.......................................................................... M. gentilii Spinelli & Grogan

4. Legs with numerous long bristly setae......................................................... M. setosa Wirth

- Legs with vestiture of short setae......................................................................... 5

5. Large species (wing length 2.70 mm); anal lobe of wing well developed, broad............. M. thoracica Ingram & Macfie

- Smaller species (wing length 0.94–1.80 mm); anal lobe of wing poorly developed.................................. 6

6. Tarsal claws with bifid tips..................................................... M. paracaudata Grogan & Wirth

- Tarsal claws with entire pointed tips...................................................................... 7

7. Wing with intercalary vein in cell r 3 (Fig. 28)............................................................... 8

- Wing without intercalary vein in cell r 3 (Figs. 3, 10)......................................................... 10

8. Intercalary vein very faint, not forked (Fig. 28)................................................... .. M. sirii n. sp.

- Intercalary vein forked................................................................................. 9

9. Flagellomeres 9–13 greatly elongate, antennal ratio1.61................................. M. wirthi Spinelli & Grogan

- Flagellomeres 9–13 very short, antennal ratio 1.00..................................... M. caudata Ingram & Macfie

10. Proximal 1/3 of wing membrane whitish hyaline, clearly contrasting with distal 2/3 darkly infuscated............................................................................................ M. fuscipennis Spinelli & Grogan

- Wing membrane hyaline or slightly infuscated, but uniformly pigmented (only slightly darkest on distal ½ of cell r 3 in M. donatoi n. sp.)....................................................................................... 11

11. Small species (wing length 0.94 mm); flagellomeres 9–13 very short (antennal ratio 0.59)............... M. kuscheli Wirth

- Larger species (wing length 1.27–1.80 mm); flagellomeres 9–13 elongate (antennal ratio1.10–1.36)................... 12

12. Thorax, excluding legs, dark brown, legs and abdomen yellowish (Figs. 2, 4).......................... M. bassoi n. sp.

- Thorax and abdomen with same coloration................................................................ 13

13. Halter pale; spermathecae spheroidal with short necks.................................... M. irwini Grogan & Wirth

- Halter light or dark brown; spermathecae ovoid with long, slender necks........................................ 14

14. Wing membrane infuscated brown, slightly darkest on distal ½ of cell r 3 (Fig. 10); spermathecae large (longest 80–82 µm long) with necks ca. 20 µm long................................................................. M. donatoi n. sp.

- Wing membrane uniformly lightly infuscated; spermathecae smaller (longest 53 µm long) necks ca. 15 µm long....................................................................................... M. yamana Spinelli & Grogan

15. Tip of parameres with hooked, slender process (Figs. 41, 49).................................................. 16

- Tip of parameres without hooked process (Figs. 37, 39, 43, 45, 47)..............................................17

16. Antennal flagellomeres 4–9 fused (Fig. 15); second radial cell 0.95–1.76x longer than first; distal portion of aedeagus heavily sclerotized, slender, with bifid tip (Fig. 42).................................................... M. kuscheli Wirth

- Antennal flagellomeres 4–9 separated (Fig. 33); second radial cell twice as long as first (Fig. 35); distal portion of aedeagus lightly sclerotized, ending in a quadrate hyaline process (Figs. 36, 50)........................... M. ventanensis n. sp.

17. Legs with numerous long bristly setae.......................................................... M. setosa Wirth

- Legs with vestiture of short setae........................................................................ 18

18. Gonostylus bent abruptly subapically at 90°.......................................... M. gentilii Spinelli & Grogan

- Gonostylus curved or straight, but not bent abruptly subapically at 90°.......................................... 19

19. Aedeagus Y-shaped or V-shaped, basal arch stout or slender, distal portion short or elongate (Figs. 46, 48).............. 20

- Aedeagus triangular or tongue-shaped (Figs. 38, 40, 44, 50)................................................... 23

20. Large species (wing length 2.20 mm); aedeagus Y-shaped, with slender basal arch and distal portion elongate, slender; scutum, scutellum and post-scutellum golden brown; anal lobe of wing well developed, broad....... M. thoracica Ingram & Macfie

- Smaller species (wing length 0.80–1.74 mm); aedeagus with stout basal arch and distal portion short; scutum, scutellum and post-scutellum dark brown; anal lobe of wing poorly developed............................................... 21

21. Sternite 9 with posteromedian excavation......................................... M. paracaudata Grogan & Wirth

- Sternite 9 without posteromedian excavation (Figs. 25, 32)................................................... 22

22. Aedeagus V-shaped, very broad basally, broader than bases of parameres, distal portion triangular, divided medially, apices slightly divergent (Fig. 46); distal portion of parameres stout, nearly straight, slightly divergent distally, apex rounded (Fig. 45)................................................................................... M. morenoi n. sp.

- Aedeagus Y-shaped, moderately narrow basally, slightly narrower than bases of parameres, distal portion slender, apex entire, pointed (Fig. 48); distal portion of parameres slender, apices tapered, divergent, with pointed tips (Fig. 47).... M. sirii n. sp.

23. Gonostylus abruptly curved at mid-length, distal ½ highly modified with basomesal hump and broad foot-shaped apex (Fig. 7); distal portion of parameres with bulbous tips (Figs. 7, 37)......................................... M. bassoi n. sp.

- Gonostylus curved or nearly straight, distal ½ not modified (Figs. 14, 21); distal portion of parameres nearly straight, slender or stout, without bulbous tip (Figs. 39, 43)................................................................ 24

24. Parameres disjunct (Figs. 39, 43); gonostylus moderately curved with broad tip (Figs. 14, 21)....................... 25

- Parameres entire; gonostylus greatly curved with pointed tip.................................................. 27

25. Distal portion of parameres disjunct at mid-length.................................... M. yamana Spinelli & Grogan

- Distal portion of parameres disjunct subapically (Figs. 39, 43)................................................. 26

26. Apicolateral process of tergite10 with short inner peg; sternite 9 with narrow shallow posteromedian excavation; gonostylus 0.85 length of gonocoxite (Fig. 14); aedeagus with convex lateral margins and slender basal arms (Fig. 40).................................................................................................... M. donatoi n. sp.

- Apicolateral process of tergite 10 without short peg; sternite 9 with deep posteromedian excavation; gonostylus 0.69 length of gonocoxite (Fig. 21); aedeagus with straight lateral margins and stout basal arms with truncate apices (Fig. 44)...................................................................................... M. monotheca Spinelli & Grogan

27. Gonostylus nearly straight, moderately short (length 0.50 mm); distal portion of parameres with tips bent 90°............................................................................................ M. irwini Grogan & Wirth

- Gonostylus greatly curved, elongate (length 0.77–0.85 mm); distal portion of parameres tapering near apex with slightly bent pointed tips......................................................................................... 28

28. Cerci elongate, extending beyond tergite 10; aedeagus triangular, basal arch extending ½ of total length, tip pointed; distal portions of parameres divergent.................................................... M. similis Spinelli & Grogan

- Cerci shorter, not extending beyond tergite 10; aedeagus with very shallow basal arch, tip truncate; distal portions of parameres parallel....................................................................... M. caudata Ingram & Macfie