[The elytra have three costae between the sutural costa and the margin. The costa closest to the sutural costa is designated costa 1.]

1. Epipleural fold ending near middle of ventrite IV and replaced thereafter by a thin carina composed of small tubercles (tuberculata group )....................................2

1′. Epipleural fold reaching elytral apex (costata group)...........................................................4

2. Costa 2 contiguous from base to near apex, or if interrupted by short gaps, alignment of intact costal sections is maintained (Fig. 2).......... Rhagodera tuberculata Mannerheim

2′. Costa 2 absent or broadly interrupted in apical third................................................................. 3

3. Costa 2 absent (disjunct tubercles present in non-linear formation) except for short ridge on distal 1/5 of elytron (Fig. 4); subantennal groove present......................................................... Rhagodera co s taefragmenta Krinsky, new species

3′. Costa 2 contiguous for 2/3 of length followed by a broad interruption before apical portion of costa (Fig. 3); subantennal groove absent........................... Rhagodera interrupta Stephan

4. Pronotum with lateral margin sinuate before distinct hind angle; small, round prominence present between discal costa and lateral margin. Junction of elytral costae 1 and 2 near apex noticeably raised, higher than either costa. Arizona............... Rhagodera costata Horn

4′. Pronotum with lateral margins evenly rounded, hind angles indistinct; prominence between discal costa and lateral margin absent. Junction of elytral costae 1 and 2 near apex not noticeably raised. Texas.............................................................. Rhagodera texana Stephan