I've been growing a red fruited eggplant from seeds which were given to
me as "Turkish eggplant". I don't think it's S.melongena because the
flowers are relatively small and white instead of purple, the calyx is
much smaller and rounder, the leaves are somewhat different in shape
and the plant is less hairy and not at all prickly. Whatever it is, it
does very well in my short season garden, even better than the earliest
cultivars of S.melongena, although this year it's proving to be
miserably susceptible to some kind of fruit worm that's also getting
some of my peppers, unlike the other eggplants which appear to be
immune.

At any rate, on the net I see Hmong red eggplants mentioned, and a lot
of culinary Solanum species like S.aethiopica that have yellow or
orange fruits. I've also got a white fruited variety that may or may
not be S.melongena, which is also very early and productive for me.

Is there a key on the web for the eggplant-like species of Solanum that
are in cultivation? I realize that plants get very diverse in
appearance when people grow them widely over many centuries, but I'm
hoping I can identify these plants because I'd like to put the seeds in
a seed exchange under the correct name. Solanum is such a huge genus
that I'd like to narrow things down. Is there a sub-genus name for the
eggplant-like ones of Asia and Africa?

Any links or opinions would be welcome. Searching on "Turkish
eggplant" brings up thousands of delicious recipes for S.melongena.
;-) "red eggplant" and Solanum gives fewer hits, but mostly ignorant
gardeners like myself.