*ekwos, equus hemonius khur?

Is the jury still out or is it settled that *ekwos connoted equus
caballus spp. Linnaeus?

Are there PIE terms for 'foal', 'mare', 'ridle' or 'cheek-piece'? If
not, *ekwos could have referred to a domesticated onager (which was
used to draw chariots in Mesopotamia)?

The term *ekwos for `horse' as Proto-Indo-European only indicates
that the horse was known to the speakers of the language; it does not
indicate that the term in fact denoted a domesticated horse.
Dolgopolsky observes that in horse-breeding cultures, there are words
for `mare' and `foal'; these terms cannot be reconstructed for PIE;
hence, he surmises that the term *ekwos must have denoted a wild
horse. (Dolgopolsky, 1990-1993, More about the Indo-European Homeland
problem, Mediterranean Language Review, 6-7: 230-248, pp. 240-241).
Similar arguments are echoed by Diebold: `IE linguists can agree on
the reconstructed Proto-Indo-European *ekwos `horse'… But let us note
(that) the animal terms tell us, in and of themselves, nothing about
the cultural uses of those animal or even whether they were
domesticated; but only that Proto-Indo-European speakers knew of some
kind of horse… although not which equid… The fact that the equid
*ekwos was the domesticated Equus caballus spp. Linnaeus… come(s) not
from etymology but rathern from archaeology and paleontology. The
most we can do with these prehistoric etyma and their reconstructed
proto-meanings, without archaeological and paleontological evidence
(which does indeed implicate domestication), is to aver a Proto-Indo-
European familiarity with these beasts.' (Richard A. Diebold Jr.,
1987, Linguistic ways to Prehistory in: Proto-Indo-European: The
archaeology of a lingistic problem, 19-71, ed. Susan Skomal and Edgar
Polome, Washington D.C.: Institute for the Study of Man, pp. 53-54).
The debate is still on if the term could have referred to an onager,
Equus hemonius khur which is native to northwestern South Asia.
Armenian e_s' means donkey.