Key to species of adult Thecomyia (based primarily on males)

1 Upper orbital seta present (sometimes very weak in T. longicornis); rostrum in males not more than 0.7 as high as eye; white, microtomentose infra­ocular wedge not extending farther than 2/3 of distance from eye to oral margin; mid and hind femora blackish at apex or sometimes wholly yellowish; posterior surstylus distinct from the anterior one, pointed, projecting, except anterior absent in T. longicornis ................. 2

­ Upper orbital seta lacking; rostrum as much as 0.76 as high as eye (reaching 0.97 in some females); white, microtomentose infra­ocular marking in male of T. limbata extending nearly to oral margin; mid and hind femora usually wholly yellowish; posterior surstylus various .................................................................................................... 5

2 Tergite 5 nearly wholly golden yellow, brown at most in narrow basal margin; mid and hind femora with distinct, narrow brownish apices; mid femur with small seta in anterior distal 1/2; medial mesonotal stripe simple, golden yellow; male postabdomen as in Fig. 12, posterior surstylus well developed, clawlike ........... T. chrysacra new species

­ Tergite 5 largely brown, golden yellow laterally and sometimes narrowly apically; mid and hind femora wholly yellowish; mid femur usually lacking medial anterior seta; medial mesonotal stripe simple or tripartite; posterior surstylus various .................... 3

3 Medial mesonotal stripe simple, golden yellow; anterior surstylus absent, posterior consisting of narrow non­protuberant bar lying parallel to lower margin of epandrium (Fig. 6) T. longicornis Perty

­ Medial mesonotal stripe tripartite or evanescent anteriorly, yellow only for short distance before scutellum, otherwise gray; posterior surstylus distinct from the anterior one, triangular .............................................................................................................. 4

4 Anterior basiphallic process curved, clawlike; phallapodeme with distinct anterior process (Fig. 16) ........................................................................ T. signorelli new species

­ Anterior basiphallic process cuneate, apically tripartite; phallapodeme with only traces of anterior process (Fig. 17) .................................................. T. tricuneata new species

5 White, microtomentose infra­ocular marking extending well over halfway to oral margin, in male nearly all the way; mid femur with anteromedial seta; posterior surstylus clawlike, distiphallus with long slender curved prongs (Fig. 8) ..................................... ................................................................................................. T. limbata (Wiedemann)

­ White, microtomentose infra­ocular marking extending little more than halfway to oral margin; mid femur with or without anteromedial seta; male postabdomen various .... ...................................................................................................................................... 6

6 Anterior surstylus well developed, posterior triangular to ovate, strongly projecting. 7

­ Anterior surstylus absent, posterior appearing as a bar ............................................... 9

7 Anterior surstylus very short, setose, much less than 1/2 as long as triangular posterior surstylus; posterior surstylus not curved forward; distiphallus without long slender prongs (Fig. 10) ..................................................................... T. autazensis new species

­ Anterior surstylus slender, curved, more than 1/2 as long as ovate posterior surstylus ...................................................................................................................................... 8

8 Male postabdomen as in Fig. 14; phallapodeme a blunt­tipped process; distiphallus rather narrow; mid femur with anteromedial seta ................. T. naponica new species

­ Male postabdomen as in Fig. 15; phallapodeme with clawlike process; distiphallus broad, expansive; mid femur without anteromedial seta ....... T. papaveroi new species

9 Distiphallus with 4 straight processes, 3 slender and pointed and 1 wide; basiphallus spatulate, with truncate, tricuspidate tip (Fig. 9); fronto­orbital spot very broad, more than 1/3 of frontal width....................................................... T. abercrombiei new species

­ Distiphallus with 2 or 3 processes; basiphallus well developed, more or less bifid, bicuspidate, concave; fronto­orbital spot with 1/3 of frontal width or less ............... 10

10 Acrophallus strongly coiled (Fig. 7) .............................................. T. lateralis (Walker)

­ Acrophallus not strongly coiled, projecting downwards ........................................... 11

11. Acrophallus pointed, slightly curved downwards, hypandrium with membranous projections very broad (Fig. 13, 25) ................................................ T. mathisi new species

­ Acrophallus fingerlike, strongly curved downwards, hypandrium with membranous projections not so developed as above (Fig. 11, 23) ................ T. bonattoi new species