Key to the species of the ampliatus group (modified from Scarbrough 2002)

1. Hind femur mostly to entirely brown to black, sometimes basal third to two-thirds yellow to reddish yellow posteriorly (Figs 1–2, 11, 16, 26, 31, 41, 46–47)........................................................................... 2

1’. Hind femur more extensively yellow, posterior usually mostly yellow to brownish yellow or reddish, apex brown to black..................................................................................................... 21

2. Hind femur with all or most anteroventral macrosetae brown or black, 3–4 basal posteroventral macrosetae often yellow... 3

2’. Hind femur with most anteroventral macrosetae yellow or white, 1–3 anteroventral macrosetae and 3–5 posteroventral macrosetae sometimes brown or black (Figs 2, 47)........................................................... 8

3. Palpus black setose.................................................................................... 4

3’. Palpus yellow setose, at least apically..................................................................... 5

4. Scutellum with 2 marginal macrosetae; female hind femur slender; female S8 with a large shiny spot laterally, median dorsal stripe and narrow margins with dense pruinosity (Ecuador)............................ O. depressus Scarbrough, 2002 .

4’. Scutellum with 3 marginal macrosetae; female hind femur wider; female S8 entirely sparse pruinose (Guyana)...................................................................................... O. constrictus Scarbrough, 2002 .

5. Mid femur mostly yellow posteriorly, apex brown or black.................................................... 6

5’. Mid and hind femora brown to black, narrow base sometimes yellow............................................ 7

6. Mid tibia bent preapically, stout macrosetae present; hind tibia with macrosetae often arising from apical tubercles; T9+10 straight at anterior margin; spermatheca oval (Venezuela).............................. O. bullatus Scarbrough, 2002 .

6’. Mid and hind tibiae normal, without unusually stout macrosetae arising from apical tubercles; T9+10 with a U indentation with lateral small processes at anterior margin; spermatheca rounded (Brazil).......... O. aubreyi Vieira, Bravo & Rafael, 2011 .

7. Fore femur mostly yellow; dorsal apical third of epandrium with abrupt, deep emargination, crescent-shaped, apex acutely pointed; gonocoxite with 3–4 setae; gonostylus with two apical processes; phallus tubular, strongly curved dorsally, apex well beyond parameral sheath; female S8 with medioapical margin broadly truncate; spermatheca parabolical (Costa Rica)................................................................................... O. lunatus Scarbrough, 2002 .

7’. Fore femur mostly black; apical third of epandrium narrow, dorsal margin angled posteriorly to pointed apex; gonocoxite with 1 long thick macroseta; gonostylus narrow, acutely angled apically; phallus with apex beyond parameral sheath; female S8 with medioapical margin produced, corners rounded, spermatheca obovate (Venezuela)............ O. ayalai Scarbrough, 2002 .

8. Fore and mid femora brown to black, narrow base sometimes red or yellow (Figs 1, 11)............................. 9

8’. Fore and mid femora at least yellow on basal third to half posteriorly (Figs 16, 26, 31, 41).......................... 13

9. Epandrium ending in a narrow process, clavate or rod-like apically (Fig. 5)...................................... 10

9’. Epandrium ending in an angular process, pointed or rounded apically........................................... 11

10. Wing hyaline, costal cell yellow; epandrium enlarged anteriorly and gradually narrowing to a clavate distal process; subepandrial sclerite only slightly pronounced distally, straight dorsally; gonocoxite with 3 long, thin macrosetae; female cercus slightly concave at distal margin (Colombia).............................................. O. ampliatus Scarbrough, 2002 .

10’. Wing brownish, costal cell dark brown (Fig. 3); epandrium rectangular anteriorly and abruptly narrowing to a rod-like distal process (Fig. 5); subepandrial sclerite extremely developed distally forming an arc above the terminalia (Fig. 5); gonocoxite without macrosetae (Fig. 8); female cercus rounded at distal margin (Fig.12) (Peru)............. Ommatius amaru sp. nov.

11. Epandrium triangular apically (Fig. 50); gonocoxite with 1 long, unusually thick, macroseta (Figs 51–53); phallus narrow apically (Fig. 55).................................................................................... 12

11’. Epandrium horizontal apically; gonocoxite with only setae, macroseta absent; phallus wide apically (Mexico, Guatemala).............................................................................. O. gladiatus Scarbrough, 2002 .

12. Males with vein C dilated anteriorly (Fig. 48); subepandrial sclerite wide proximally, tapering distally in ventral view (Fig. 57); hypandrium with a small finger-like process distally (Figs 52–53); gonostylus flat-like basally pronounced externally and bent knee-like medially towards a pointed apex (Figs 52–53); ejaculatory apodeme pronounced proximal dorsally resembling a golf club, rod-like distally; phallus curved down distally (Fig. 55) (Peru)....................... Ommatius yanantin sp. nov.

12’. Males with vein C not dilated anteriorly; subepandrial sclerite subrectangular in ventral view; hypandrium rounded distally, without process; gonostylus rod-like basally, tapering distally, conic shaped in ventral view; ejaculatory apodeme wide proximally, with a dorsal keel distally; phallus straight to body axis (Ecuador).................. O. nanciae Vieira, 2015 .

13. Palpus mostly to entirely brown setose................................................................... 14

13’. Palpus entirely yellow setose........................................................................... 16

14. Hind femur dark reddish brown to almost black, extreme base yellow (Fig. 62); hind tibia with apical third to apical half dark yellow to brown (Fig. 58).............................................................................. 15

14’. Hind femur shining black, extreme base dark reddish; hind tibia with apical half dark brown to almost black (Fig. 16) (Peru)................................................................................ Ommatius kuntur sp. nov.

15. Hind femur dark with most ventral macrosetae yellow (Fig. 62); mid femur with only long, posteroventral setae; T9+10 with apical corner concave, spoon-shaped (Figs 64–65); S8 with deep notch laterally, surface concave with 1 stout macroseta, corner and medioapical margin equally produced forward (Figs 64–65) (Peru).................. O. quadratus Scarbrough, 2002 .

15’. Hind femur with most ventral macrosetae brown; mid femur with 1 brown, posteroventral macroseta on apical third; T9+10 with apical corner truncate; S8 with medioapical margin far forward of corners, lateral notch with stout macroseta absent (Peru)........................................................................ O. ovatus Scarbrough, 2002 .

16. Male with unusually thick gonocoxal macrosetae, apex round................................................. 17

16’. Male without unusually thick gonocoxal macrosetae (Figs 39–40) (Peru)................... Ommatius uturuncu sp. nov.

17. Fore and mid femora posteriorly brown on apical half....................................................... 18

17’. Fore and mid femora posteriorly brown on apical fourth to third............................................... 19

18. Scutellum with two brown to black, marginal macrosetae; hind femur usually with mostly yellowish ventral macrosetae, apical 1–2 macrosetae in each row black; long gonocoxal macrosetae present; gonostylus with apical third abruptly angular; hypoproct with basal process slightly produced, J-shaped (Colombia)........................... O. angulosus Scarbrough, 2002 .

18’. Scutellum with two yellow marginal macrosetae; hind femur with yellow basal macrosetae, apical 5 posteroventral macrosetae black; short, curved gonocoxal macrosetae present; gonostylus axe-shape, apical third unusually narrow, base much wider, subrectangular; hypoproct with basal process broadly triangular (Colombia)........... O. dolabriformis Scarbrough, 2002 .

19. Female T9+10 and genital fork fused as a wide, dark sclerotized bridge ventrally; T9+10 folded laterally forming a prominent keel; genital fork with 2 large, oval depressions present medially; S8 with apical margin strongly and abruptly produced medially; spermatheca oval (Bolivia)............................................... O. tropidus Scarbrough, 2002 .

19’. Female T9+10 and genital fork normal; T9+10 apical corner pointed, genital fork membranous, only small depressions present; S8 with apical margin only narrowly produced medially; spermatheca wider basally than apically or spherical........... 20

20. Male terminalia wider than long, epandrium with a wide notch along dorsoapical margin, and angled obliquely posteriorly; gonocoxal macrosetae unusually long and pointed; gonostylus with strong right angled basal process; phallus apically wide, angled ventrally, parameral sheath hood-like; female S8 with apical margin medially broadly produced, sides oblique; spermatheca spherical (Peru)................................................. O. tanpadiensis Scarbrough, 2002 .

20’. Male terminalia longer than wide, epandrium only slightly notched along dorsoapical margin, and horizontal, not especially angled posteriorly; gonocoxal macrosetae shorter, apex round; gonostylus flat, without prominent lateral process basally; phallus horizontal, parameral sheath flared preapically, not hood-like; female S8 with apical margin slightly produced medially, narrow with almost vertical sides; spermatheca wider basally than apically (Venezuela)......... O. flexus Scarbrough, 2002 .

21. Hind femur with most or all ventral macrosetae brown....................................................... 22

21’. Hind femur with most or all ventral macrosetae yellow...................................................... 24

22. Hind coxa entirely, fore and mid coxae apically usually red to brown yellow; femora yellow-brown with reddish tint, darkest apically, lighter yellow to reddish yellow basally and posteriorly; hind femur basally with 1–2 contrastingly stout posteroventral macrosetae; epandrium abruptly narrow apically; gonocoxite with sparse setae; spermatheca elliptical (Guatemala to Panama).......................................................................... O. angustatus Scarbrough, 2002 .

22’. Coxae darker, brown to black; femora never reddish, dull yellow-brown anteriorly and dorsally or mostly yellow; hind femur basally without contrastingly stout posteroventral macrosetae; epandrium not abruptly narrowing apically; gonocoxite with an unusually thick macroseta; spermatheca spherical or ovate.................................................... 23

23. Hind femur dull yellow-brown dorsally and anteriorly, yellow elsewhere, most anteroventral macrosetae yellowish; mid femur of male with preapical, posterodorsal macrosetae absent, 5–6 long, posteroventral macrosetae present, none beyond middle; epandrium wide apically, pointed; gonocoxite with two digitate processes on inner corner, one hooked with a moderate thick, acuminate, black macroseta; female S8 rectangular apically, spermatheca spherical (Peru).... O. destitutus Scarbrough, 2002 .

23’. Hind femur mostly yellow, brown-yellow to brown apically, darkest dorsally, anteroventral macrosetae brown; mid femur with preapical, posterodorsal macrosetae, male with only long, posteroventral setae basally, short, posteroventral macrosetae often present on apical third; epandrium triangular apically, gradually tapering to a pointed apex; gonocoxite with inner corner wide, margin oblique with one short, thick macroseta; female S8 with medioapical margin curved anteriorly, sides oblique; spermatheca ovate (Venezuela)................................................ O. triangularis Scarbrough, 2002 .

24. Femora dorsally and at least dorsal half anteriorly dark brown, ventrally and posteriorly yellow, demarcation between colors abrupt............................................................................................. 25

24’. Femora with colors more diffuse, brown to yellow transition gradual over a wider area, never abrupt (Venezuela).................................................................................... O. fernandezi Scarbrough, 2002 .

25. Epandrium wide apically, apex pointed, gonocoxite with a large, flat, “fang-like” macroseta; female with medioapical margin of S8 curved forward, sides oblique (Venezuela).................................. O. unguiculatus Scarbrough, 2002 .

25’. Epandrium narrow apically, apex round, gonocoxite with sparse setae only; female with medioapical margin of S8 rectangular, sides almost parallel (Bolivia, Argentina)....................................... O. tucumanensis Scarbrough, 2002 .