Underside features that distinguish these two include the submarginal markings and the postdiscal spots. In
arion the submarginal markings look very clearly like a twin series, the outer marks being quite deeply branded; the postdiscal spots on the forewing are larger than those on the hindwing and usually elongate or oval. In
rebeli the submarginal markings look like a single series (the inner series) with a dark shadow outside; the postdiscal spots on the forewing are small and usually circular.
To illustrate this, here is a
rebeli male:
This is a pair of arion:
Both Paul's insects fit the bill for
rebeli, though the submarginal markings on the hindwing of the first are quite strong. The upperside of the first is obviously not like either species, but it is easier to imagine
rebeli wearing down to that state than
arion miraculously losing all trace of postdiscal spotting.
In short, I think they're both
rebeli. I have less confidence with the first one.
Rev's hesitation is natural - especially as the upperside of the first one really doesn't look like a male
rebeli (it is definitely a male)!! For those who don't know the species, this is what a fresh male rebeli looks like (in fact, the same male as in the underside picture above):
But those pictures were taken on 4th June. Paul's were probably a month later.
The extent of blue under the wings is variable. I haven't got a copy of H & R with me in England but I seem to recall them noting that there was more in
rebeli than
alcon (which they regarded as subspecies, as is current fashion).
Guy