Key to the species of Ctenomelynthus

1 Meta-acetabulae yellow to yellowish white................................................................. 2

- Meta-acetabulae shiny reddish brown or shiny black tinged or without metallic bluish green reflections, with posterior border eventually yellow and never with posterio lobe entirely yellowish white.......................................... 3

2 Pro-, meso-, and metapleura shiny brick red; fore and middle femora unicolorous, pale castaneous orange; abdominal sterna III to VII on female with seven alternate longitudinal stripes, four of them yellow to yellowish white and three brick red to dark reddish castaneous......................................................................... coxaliS Breddin

- Inner half of pro-, meso-, and metapleura with yellow, lengthwise stripe that covers the acetabulae and upper half with wide metallic green stripe; fore and middle femora bicolorous, yellow with external pale brown stripe; abdominal sterna III to VII of female solid yellow........................................................................ urbinuS sp. nov.

3 Callar region dark yellow to pale yellowish orange........................................................... 4

- Callar region shiny reddish brown, scattered with metallic bluish green reflections.................................. 5

4 Triangular process of pronotum elongate, broad, conspicuously surpassing the posterior border of pronotal disk; fore and middle femora dark castaneous; antennal segments I to III pale castaneous (basal third of I black) brunneiventriS Breddin (in part)

- Triangular process of pronotum short, slightly exposed; fore and middle femora pale castaneous orange; antennal segments I to III pale castaneous orange (basal third of I black)............................................... Sanchezi sp. nov.

5 Triangular process of pronotum elongate, broad, conspicuously surpassing the posterior border of pronotal disk....................................................................................... brunneiventriS Breddin (in part)

- Triangular process of pronotum short, slightly exposed........................................................ 6

6 Hind femur bicolored, dorsally shiny dark reddish brown and ventrally shiny black; coxae and trochanter shiny black to shiny reddish brown; head ventrally black with buccula and yellow longitudinal stripe close to each eye............................................................................................................ venuStuluS sp. nov.

- Hind femur shiny pale castaneous orange; fore and middle coxae and trochanter shiny pale castaneous orange; head ventrally yellow to pale orange.................................................................... inermibuS Distant