It should be noted that the following notes are based upon my observations of many specimens sent to me for identification, but I have not examined type material.  From the examination of quite a few specimens from various collections, I have come to the conclusion that there is quite a bit of variability in the size and shape of the humeral angles which has resulted in the description of more species than there actually are. For example:

1) I now suspect that Carbula scutellata Distant is probably a junior synonym of Carbula socia (Walker). Distant (1902) states that the difference between the two are: Carbula socia is "allied to the preceding species C. scutellata, but differing by the pronotal angles, which are much more obtuse; head broader and less narrowed anteriorly, scutellum more thickly punctate, etc." Most specimens I have examined have the humeral angles distinctly spinose, a couple specimens have the humeral angles much more obtusely rounded, and there are some intermediates. I did not notice any difference in the head shape; there may be a slight tendency for the scutellum to be more thickly punctate on those specimens with rounded humeral angles. I did not see any significant differences in the male or female genitalia in any of the specimens examined.

2) I also suspect that Carbula insocia (Walker) is probably a junior synonym of Carbula biguttata (Fabricius). Again, the main difference between these two forms is the humeral angles of insocia are more spinose (rounded in C. biguttata), and the pale ivory spots in the basal angles of the scutellum tend to be larger in C. insocia. There appears to be intermediate forms of the humeral angles, and I have examined some specimens with rounded humeral angles with larger basal scutellar spots. Again, I have not noticed any significant differences in the male or female genitalia among any of the specimens examined.

Comments on other Indian species:

1) It is obvious that Carbula crassiventris (Dallas), Carbula indica (Westwood), and Carbula rugosa Distant are all closely related. I have specimens of C. crassiventris from Taiwan, and have seen specimens from other areas of China and perhaps Java. They have the humeral angles quite produced but still narrowly obtuse, the tips are often pale orange-brown in color. The California Academy of Sciences (CASC) has a nice series of specimens from southern India that are apparently related to C. crassiventris, but the humeral angles are only slightly prominent, and they are more broadly rounded. There are differences in the male genitalia however (crassiventris has a more prominent lateral lobe on the paramere than does this taxon). Distant described C. rugulosa as being related to crassiventris and having much more rounded humeral angles. He described the anterior disk of the pronotum as being more or less rugulose; there is some slight indication of rugulose pale lines on a few of the specimens, but not all. Distant (1902) also discussed C. indica, indicating that it was also related to C. crassiventris, but that its humeral angles where somewhat intermediate in form between C. crassiventris and C. rugulosa. CASC also had one specimen from northern India that was not in good shape, but the humeral angles were somewhat intermediate between the two, and the external male genitalia appeared to be slightly different. Until I examine more specimens, I regard all three species as being valid with C. crassiventris being more Oriental, C. indica being more northern India, and C. rugulosa being southern India in distribution.

2) CASC also had a long series of another Carbula species from southern India that does not seem to match well with any known described species. All specimens have the humeral angles rounded, not at all prominent, and they have the head and anterior disk of the pronotum almost pitchy black; the overall coloration is also very dark. The antennal segments are pale with distinct black bands on the 4^th and 5^th segments.

3) Distant (1902) also included C. producta, but it appears to be more from Myanmar. Its humeral angles are described as "strongly and robustly produced." This thus eliminating it as a possibility for the species described above in no. 3.