Key to the Characidium species from the trans-Andean basins of Colombia

1a. Isthmus and chest lacking scales........................................... Characidium cf. boavistae (Figs. 2k, l)

1b. Isthmus and chest scaled............................................................................... 2

2a. Sides of body with well-defined black spots located on, above and below a dark lateral stripe; dorsum crossed by 7–10 vertical bars that do not reach below lateral stripe......................................... C. phoxocephalum (Figs. 2b, d)

2b. Sides of body without well-defined black spots; dorsum without vertical bars (in adult males of C. caucanum) or with 6–18 vertical bars crossing dorsum (mean = 11), some of which reaching well below the horizontal lateral stripe... 3 (Fig. 2a, c, e)

3a. Caudal-fin mark not forming a well-defined spot on peduncle, but dark pigment present on middle caudal-fin rays........................................................................................... 4 (Figs. 2a, b, c, g, e, f)

3b. Caudal-fin mark present as well-defined spot on peduncle, dark pigment not extending onto middle caudal-fin rays.......................................................................................... 5 (Figs. 2g, h, i, j, k, l)

4a. Vertical bars on body narrow (1/2–1 scale wide) and sinuous, not cuneate-shaped, usually 11 or more in juveniles and females, or sides of body without vertical bars in adult males............................ Characidium caucanum (Fig. 2a, c, e)

4b. Vertical bars on body wide (up to four scales wide at widest dorsal end), anteriormost cuneate-shaped with vertex pointing down and reaching to, or just below, lateral line, posterior bars (1–4 counted from caudal-fin base) reaching well below the lateral line to ventral margin of caudal peduncle, usually fewer than 12 vertical bars present on sides of body (range 7–12)................................................................ Characidium chancoense, new species (Fig. 2f)

5a. Sides of body with 9–10 wide vertical bars, none cuneate-shaped; body depth at origin of dorsal fin 19.9–25.8 % in SL, mean 25.5.................................................................. Characidium sanctjohanni (Fig. 2h, j)

5b. Sides of the body with 6–16 thin vertical bars, all passing well below narrow horizontal stripe, none cuneate-shaped; body slender, body depth at origin of dorsal fin 17.8–27.4 % in SL, mean 23.4............... Characidium cf. zebra (Fig. 2g, i)