The upperside ground colour of the nominate form of alveus is a dark grey-brown sometimes with a yellow flush, with smallish white marks on the upf, especially the cell, and very weak marks on the uph. The unh has no particular distinguishing features, the discal marks in s2 and s3 being quite small, but this is not unique to alveus. It is perhaps the most difficult of the French Pyrgus species to ID with any degree of confidence, and I have included some on this page that I am certainly not confident are alveus in order to invite comment. It usually seems to be a case of the "balance of probabilities" rather than "beyond reasonable doubt". The Lafranchis ID book simply says that the uph marks are dull, which is hardly a unique differentiator.

The unh ground colour is olive brown. Alveus is a large Pyrgus, larger than most of its cousins, so ID may be based more on this rather than analysis of the photo. It has a wide altitude range, from 0 to 2100m and flies in June-August.

The high altitude subspecies centralhispaniae (also called centralitaliae) is completely different to the nominate form P. a. alveus in that the upf white marks are very well-defined and the uph marks are strong and well-contrasted. The undersides of alveus and centralhispaniae appear to be very similar as far as I can ascertain. As its name implies it flies in central Spain and Italy, but I believe it also flies in the French Alpes.

observations

I've rather come to the conclusion that it must/could be alveus by the dubious process of eliminating everything else. The virtually non-existent upf cell spot rules out many species. The uph markings are pale but quite well defined, which would normally tend to rule out alveus, but it is a male and this is probably about the upper limit of strength of uph markings for this species. The colouring is rather odd, with dark brown marginal areas, lightening to sandy brown in the upf basal area, which are often an indication of Oberthur's Grizzled Skipper (P. armoricanus), but alveus can have a yellow flush, although is this actually a yellow flush? I would have expected a strong cell spot for armoricanus, though. Comment invited.

this male matches the illustration in T&L perfectly for the subspecies centralhispaniae.

my feeling is that this is spot-on for male alveus in terms of colouring and markings. The ground colour is a rather cold grey-brown and the cell spot is not sufficiently well-defined to suggest other species, nor is it outwardly concave which would suggest the Carline Skipper (P. carlinae).

I suspect this may be a male from the body length. I had some doubts as to whether this is actually alveus; the upf marks are rather strong, and the cell spot has just a suggestion of external concavity which might suggest carlinae, but 22255 is the underside and I think this swings it toward alveus.

I am fairly certain that this is a male alveus as I also have an underside shot and it was ID'd with certainty by a local expert. The upperside markings are just about spot-on for alveus and I recall that it was a large Pyrgus.

the unh markings all look right for alveus, the marginal markings, the "leaning" bump in discal s1, the very small marks in discal s2/3, although the alveus discal s6/7 are normally the same width as discal s4/5, the large rectangular mark in basal s7. The evidence is much more strongly inclined toward alveus than any other species. 22250 is the upperside.

the unh marks here all point to alveus. The discal s2/3 are completely empty, ruling out armoricanus. Basal s7 is rather rounded suggesting carlinae but the marginal mark on v5 is not sufficiently large or well defined, and the altitude is some way below carlinae's normal range.