Key to the species of Hydrometra from Colombia

1. Anterior margin of clypeus excavated (Fig. 9c); all acetabula without circular pits................... Hydrometra comata

-. Anterior margin of clypeus not excavated (Figs. 1b, 2b, 3b, 4b, 5b, 6b, 9 a–b, 9d–e); at least pro- and mesoacetabula with circular pits (Figs. 1d, 2d, 3d, 4d, 5c, 6d)....................................................................... 2

2. Pro- and mesoacetabula with at most 7 circular pits each (Figs. 5c, 6d)........................................... 3

-. Pro- and mesoacetabula with at least 13 circular pits each (Figs. 1d, 2d, 3d, 4d).................................... 5

3. Metacetabulum without circular pits; male abdominal sternum VII with a pair of spinose projections anteriorly (Figs. 10 a–b).................................................................................... Hydrometra argentina

-. Metacetabulum with circular pits (Fig. 5c, Fig. 6d); male abdominal sternum VII with brushes, setae, depression or subconical processes............................................................................................ 4

4. Clypeus broad, with anterior margin rounded (Fig. 6b); pro- and mesoacetabula with 2–5 circular pits each (Fig. 6d); metacetabulum with 2–6 circular pits (Fig. 6d); male abdominal sternum VII with several shining long setae (Figs. 6 e–f).............................................................................................. Hydrometra adnexa

-. Clypeus conate, with anterior margin projected centrally (Fig. 5b); pro- and mesoacetabula with 5–7 circular pits each (Fig. 5c); metacetabulum with 10–13 circular pits (Fig. 5c); male abdominal sternum VII with a very large oval depression on each side of the midline, the depressions fringed with setae which are longer and stiffer on the anterior margin (Figs. 10 g–h)......................................................................................... Hydrometra williamsi

5. Clypeus very broad, with sides parallel (Fig. 9e); male abdominal sternum VII with a pair of short, mammilose projections near anterior margin (Figs. 10 e–f); male abdominal segment VIII with a tubercle covered by setae on each side (Figs. 10 e–f)… Hydrometra olallai

-. Clypeus narrower, with sides rounded or converging anteriorly (Figs. 1b, 2b, 3b, 4b, 9b, 9d); male abdominal sternum VII with a pair of brushes of setae (Figs. 1 e–f, 10c–d, 10i–j) or a pair of subconical processes (Figs. 3 e–f, 4e–f); male abdominal segment VIII with or without lateral tubercles.................................................................. 6

6. Clypeus with anterior margin pointed (Figs. 9b, 9d). General color always brown................................... 7

-. Clypeus with anterior margin rounded (Figs. 1b, 2b, 3b, 4b). General color yellow, yellowish brown or brown............ 8

7. Clypeus with an angular median projection anteriorly (Fig. 9d); male abdominal sternum VII with brushes located on the posterior half of the segment (Figs. 10 i–j).................................................... Hydrometra guianana

-. Clypeus with a blunt median projection anteriorly (Fig. 9b); male abdominal sternum VII with brushes located on the middle of the segment (Figs. 10 c–d)............................................................. Hydrometra caraiba

8. General color yellow or yellowish brown (Figs. 1, 2, 3); dorsal interocular groove present............................ 9

-. General color dark brown (Fig. 4); dorsal interocular groove absent; male abdominal sternum VII with a pair of subconical processes (Figs. 4 e–f). Female unknown.......................................... Hydrometra quimbaya sp. nov.

9. General color yellow (Fig. 3); clypeus broader, with lateral and posterior margins rounded (Fig. 3b); dorsal and ventral interocular groove shallow; male abdominal sternite VII with a pair of subconical processes (Figs. 3 e–f). Female unknown...................................................................................... Hydrometra tayrona sp. nov.

-. General color yellowish brown (Figs. 1, 2); clypeus narrower, with lateral margins straight (Figs. 1b, 2b); dorsal and ventral interocular groove deep; brushes of male abdominal sternite VII subrectangular (Figs. 1 e–f)..................................................................................................... Hydrometra colombiana sp. nov.