Key to species of Colobostema Enderlein in the Neotropical Region (males only)

1.- Tergite 7 with subbasal constriction (Figs 4C, G, I)........................................................... 2

-. Tergite 7 without subbasal constriction (Figs. 4A, E).......................................................... 4

2(1). Tergite 7 asymmetrical (Fig. 4G); CuA1 incurved anteriorly at apex, ending before level of apex of costa (Fig. 3 E).......................................................................................... C. lupitae (Mx, Oaxaca)

-. Tergite 7 symmetrical (Fig. 4C, I); CuA1 not curved at apex, extending beyond apex of costa (Fig. 3 B, 3F).............. 3

3(2). Tergite 9 rounded apically (Fig. 7 E); sternite 7 with deep posterior emargination (Fig. 4J); paramere (Fig. 6 E)............................................................................................ C. marlettae (Mx, Yucatan)

-. Tergite 9 V-shaped, acute apically (Fig. 7 B); sternite 7 with a shallow posterior emargination (Fig. 4D); paramere (Fig. 6 B)........................................................................... C. marielae (Mx, San Luis Potosi)

4(1). Paramere apically with short setae........................................................................ 5

-. Paramere apically with strong setae (Fig. 6)................................................................. 6

5(4). Tergite 9 apically bilobed; paramere very small, not reaching the medial length of the gonocoxite............................................................................................ C. rotundum Cook (Panama, Tocumen)

-. Tergite 9 apically rounded; paramere similar in length of gonocoxite........ C. hoffmannae Huerta & Ibáñez (Mx, Yucatan)

6(4). Gonocoxite modified along posterior margin (bilobed or with crenulations)........................................ 7

-. Gonocoxite not modified along posterior margin, simple and smooth............................................. 8

7(6). Paramere bearing long setae, as long as length of paramere (Fig. 6 C); gonocoxite with crenulations (Fig. 5 C); tergite 7 simple (Fig. 4E); wing with M fork constricted medially (Fig. 3 C)............................... C. valentinae (Mx, Jalisco)

-. Paramere with setae much shorter than paramere; gonocoxite bilobed, without crenulations; tergite 7 posteriorly produced on each side, emarginated medially; wing with M fork not constricted..... C. arizonense Cook (Nearctic, Mx, Baja California)

8(6). Tergite 9 elongated, extending beyond apex of gonocoxite (Fig. 5 A); CuA2 ends before level of apex of costa (Fig. 3 A).................................................................................... C. emilianoi (Mx, Chiapas)

-. Tergite 9 short not extending beyond apex of gonocoxite; CuA2 extending beyond level of apex of costa................ 9

9(8). Tergite 7 with posterior emargination; CuA2 sigmoid............. C. variatum Cook (Nearctic; Neotropical (Mx, Yucatan)

-. Tergite 7 broadly quadrangular, medially produced; CuA2 more acutely angled near middle.............................................................................. C. bijleveldi Haenni & Rapp (Belize, Shipstern Nature Reserve)