Key to the species of Bregmosina

1) Lower orbital bristle conspicuously finer and less than half as long as upper orbital bristle. Male sternite 5 made up mostly of two strikingly stout, long posterolateral processes (Fig. 20). Length (antennal base to wing tip) less than 2.3 mm .......... 2

- Both orbital bristles well developed, lower bristle at least half as long as upper (Fig. 8). Male sternite 5 without long posterolateral processes. Length (antennal base to wing tip) over 2.5 mm ................................................. 3

2) Sternite 4 of male with two short posteromedial lobes (Fig. 20). Surstylus strongly recurved, apex long and pointed, much longer than width of surstylus (Fig. 21).............................................. B. obunca . Costa Rica, Guyana

- Sternite 4 of male without posteromedial lobes. Surstylus club-like, apex swollen with a short pointed process shorter than width of surstylus (Fig. 22)............................................................. B. howdeni . Ecuador

3) Male cercus with ventral point (Figs. 12, 23). Postgonite either very broad at middle or swollen at apex (Figs. 14, 26). Either second costal sector longer than third or R2+3 slightly sinuate (Fig. 10). Fore tarsomeres 2–4 and sometimes apex of tarsomere 1 flattened and wider than base of tarsomere 1. Known females with tergite 8 not shortened dorsally, longer than cercus (Fig. 16)..................................................................................................... 4

- Male cercus subquadrate, without ventral point (Fig. 5). Postgonite narrow, simple (Fig. 6). R2+3 not distinctly sinuate and second costal sector shorter than third (Fig. 3). Fore tarsomeres 3–4 short and slightly swollen but not distinctly wider than tarsomere 1. Female tergite 8 short dorsally, no longer than cercus (Fig. 1).......................... B. bucki Costa Rica

4) Fore tarsomeres 2–5 short and flat, tarsomere 1 almost parallel sided, not distally swollen (Fig. 7). R2+3 slightly sinuate, curved up at apex (Fig. 10). Eye relatively small, less than 2.5X genal height. Male abdominal sternites 2 and 3 entire................................................................................ B. ephydriformia . Costa Rica, Venezuela

- Fore tarsomeres 1–4 strikingly swollen and flattened, tarsus strongly spindle-shaped. R2+3 straight, slightly curved only at apex. Eye larger, over 2.5X genal height. Male with all abdominal sternites medially divided (Fig. 24)... B. schizosterna . Ecuador.