Key to the South American species of Mythicomyia (Heterhybos)

[modified from Hall (1976)].

1 Eyes holoptic.................................................................................... Males

- Eyes dichoptic................................................................................. Females

MALES

1 Knob of halter black, usually white below and at apex.................................................... 2

- Halter knob white or yellowish above and below............................................................ 6

2 Proboscis short, less than height of eye................................................................. 3

- Proboscis longer, either equal to or greater than height of eye.................................................. 4

3 Postpronotal lobe entirely black, posterior margin in some specimens brownish............ M. (H.) collina (Philippi, 1866)

- Postpronotal lobe white or yellow........................................................................ 5

4 Mesonotum entirely dark brown (Fig. 6); legs predominantly whitish, with light brown to brown spots in some of its structures (Fig. 3).......................................................................... M. (H.) bilobata sp. nov.

- Mesonotum with light colored stripe on lateral margin of mesonotum incised above near transverse suture, but not interrupted; legs usually entirely black................................................ M. (H.) hyalinipennis (Brèthes, 1919)

5 Proboscis not longer than height of eye, usually less................................... M. (H.) brachytis Hall, 1976

- Proboscis long, projecting at least twice eye height beyond oral margin....................... M. (H.) problis Hall, 1976

6 Middle tibia straight................................................................................... 7

- Middle tibia curved arcuate on basal half, best seen in lateral view...................... M. (H.) trepta Hall, 1976

7 Length of proboscis from oral margin equal to or greater than height of eye....................................... 9

- Length of proboscis from oral margin less than height of eye................................................... 8

8 Scutellum dull black................................................................ M. (H.) orthis Hall, 1976

- Scutellum whitish yellow..................................................... M. (H.) pusillima Edwards, 1930

9 First abdominal segment narrowly yellow in middle; diadem absent......................... M. (H.) citrina Hall, 1976

- First abdominal segment entirely black, diadem present................................... M. (H.) macra Hall, 1976

FEMALES

1 Legs black, knees at most yellow and occasionally underside of femora narrowly yellow............................. 2

- Legs predominantly yellow, sometimes basal half femora and tips of tarsi blackish................................. 6

2 Proboscis projecting beyond oral margin less tan height of eye............................................ 3

- Proboscis equal to or longer than eye height................................................................ 4

3 Light colored stripe on lateral margin of mesonotum inside above near transverse suture, but not interrupted at transverse suture; legs usually black................................................. M. (H.) hyalinipennis (Brèthes, 1919)

- Lateral pale stripe broadly interrupted at transverse suture; legs black but knees yellow........... M. (H.) orthis Hall, 1976

4 Scutellum black, or black in middle and yellow at sides....................................................... 5

- Scutellum entirely yellow, never with black............................................ M. (H.) citrina Hall, 1976

5 Proboscis equal to eye height or nearly so.......................................... M. (H.) brachytis Hall, 1976

- Length of proboscis at least three times height of eye..................................... M. (H.) macra Hall, 1976

6 Abdominal dorsum black, first segment yellowish white in middle of posterior margin only, rest of abdominal segments narrowly fasciate with yellow-white across their posterior margins or Abdominal dorsum black, tergite I entirely yellow or at least posterior and lateral margins of all segments yellow...................................................... 7

- Abdominal dorsum nearly entirely yellow; only extreme bases of all segments blacks, black color most extensive on two basal segments............................................................. M. (H.) diasema Hall, 1976

7 Proboscis at most equals eye height, usually less............................................................. 8

- Proboscis projecting at least twice eye height, usually more, middle of frons marked with a small black stripe............................................................................................ M. (H.) problis Hall, 1976

8 Abdominal segments narrowly yellow on posterior margins, bases broadly black, not reduced in extent posteriorly.................................................................................... M. (H.) collina (Philippi, 1866)

- Posterior margin of abdominal segments broadly yellow, amount of black color at base reduced posteriorly.............. 9

9 Antenna dark brown (Fig. 15); mesonotum with ground color brownish yellow, with three thick longitudinal bands (Fig. 17)................................................................................. M. (H.) bilobata sp. nov.

- Antenna black; mesonotum black with yellow markings, without longitudinal bands............. M. (H.) trepta Hall, 1976