Leptogaster Meigen

Leptogaster Meigen, 1803: 269 . Species found in Wyoming: Leptogaster arenicolus, L. aridus, L. coloradensis, L. eudicranus, L. hesperis, L. murinus, L. parvoclavus, and L. salvius .

Key to Species of Leptogaster [adapted from Martin (1957)]

1 Average of 6 to 10 bristles in mystax.......................................................................2

- Average of 12 or more bristles in mystax.....................................................................4

2 Occipital bristles black; first antennal segment black, second yellowish, third brown.................. Leptogaster aridus

- Occipital bristles white, pale or tinged with color............................................................ 3

3 First and third antennal segments black, the second red.................................... Leptogaster coloradensis

- First antennal segment polished, reddish brown, second orange yellow, third brown................ Leptogaster hesperis

4 Mystax bristles spaced closely together in a single row, rarely matted (some specimens with fewer than 12 bristles); face and occiput ochraceous or white tinged with yellow............................................. Leptogaster murinus

- Mystax bristles close together, often 2 or more rows, frequently several matted together; face white.................... 5

5 Occipital bristles black; second antennal segment totally red or yellow; all femora and tibiae with dark fasciae; gonoforceps truncated apically................................................................... Leptogaster eudicranus

- Occipital bristles pale, sometimes tinged with color; second antennal segment black, brown to reddish brown or dark red; gonoforceps not truncate apically............................................................................. 6

6 Dorsum of abdomen subshining brown; thinly gray pollinose, laterally with dense pollen; second antennal segment black..................................................................................... Leptogaster arenicolus

- Dorsum of abdomen brown pollinose, laterally gray pollinose; second antennal brown to reddish or dark red............. 7

7 Head vertex gray around ocellar tubercle; second antennal segment brown to reddish brown; thorax gray tomentose, with brown V-shaped stripe.................................................................. Leptogaster salvius

- Vertex brown; second antennal segment dark red; broad, brown thoracic median stripe........... Leptogaster parvoclavus