11774_pair_Alpes-Maritimes_30Jun08

Minimus is common in France, often very common, and occasionally seen in huge numbers at altitude. The underside is very similar to Osiris Blue (C. osiris), where minimus has (it seems to me) to have a great variety in the uns black spots, from quite light to very strong, from round to elongated, while the general arrangement of spots is very similar to osiris. The alleged difference is that the unh series of four post-discal spots is in a straight line for osiris, although sometimes the lowest spot is very slightly displaced inwardly, while for minimus the lowest spot is usually more clearly displaced internally. However, this is not always explicitly clear, and I have found the osiris unh spots in s2 and s3 to be completely missing or just vestigial in s3 only, and sometimes it simply is not the case at all. Also, the unf series of post-discal spots (except s6 at the top) is fairly straight in osiris but more clearly arched in minimus, although this is not always convincing. Minimus sometimes has faint unh marginal markings (see the female in 11774) which I have not seen in osiris.

However, if the upperside is visible, the male osiris is unmistakeable with a clear bright blue colour and a neat thin black border, whereas the male minimus is dark grey with a varying amount of dusting of pale blue scales, but never complete. The female osiris is essentially plain dark brown to black with a varying degree of basal blue scaling, whereas female minimus is plain brown to bluish-grey with no blue scaling. Osiris seems to be closely tied to its larval hostplant Sainfoin (Onobrychis viciifolia), especially the female, so if it's sitting on Sainfoin, the odds are that it is osiris.

The minimus underside sometimes needs a close look to differentiate from the Mazarine Blue (Cyaniris semiargus) especially when the uns (unf in particular) spots are bolder and rounder. Both minimus and osiris could be confused with the Provencal Short-tailed Blue (Everes alcetas) as they are of similar size and general markings, but alcetas has a hindwing bump, sometimes almost indiscernible, where the vestigial tail occurs, which minimus and osiris do not have.

observations

a male, puddling. Very few blue scales, which might have suggested female, were it not for the fact that it is puddling (which I believe to be a principally male activity - I used to think it was exclusively males, taking salts which clearly only the males do, but I have since seen females puddling presumably taking moisture).

17364 was quite large, much larger than an average minimus, but the not the first time I have found an oversized minimus.

a female, as is evident from the body shape.

a typical male underside, the fourth unh spot in s2 clearly, but only slightly, displaced inwards.

a mating pair. I suspect the female is on the right, based on size and colouring, also that it is fresher. Whenever you see a mating pair, if one is worn or damaged, it is odds-on to be the male, because it emerges earlier on balance and fights territorial battles, and the females are sought out by the males to mate with almost immediately as soon as they emerge.