6325_male_Var_3Jun07

14739_male_Var_22Apr09

22495_male_Isère_17Jul10

12548_male_Isere_10Jul08

29144_male_Var_7May12

44420_male_Alpes-Maritimes_17Jul17

26355_female_Alpes-Maritimes_05Jul11

14480_female_Rhône_12Apr09

31421_female_Côte-d'Or_24Jul12

36948_female_Var_20Apr15

7219_sex?_Var_20Jun07 - duponcheli?

Sinapis is widespread and common in southern France and often quite easy to identify in the field as it has a slow, floppy flight. I'm not quite sure how it stays airborne sometimes. Illustrations in books generally show the unh as being dusted with grey scales in a characteristic sinapis pattern, to a greater or lesser extent according to sex (females more heavily dusted) and brood (first brood more heavily dusted). However, in Var I find the second brood unh to be almost unmarked with grey scales and to have a distinct pale yellow tinge - supposedly indicators of the second brood of the Eastern Wood White (L. duponcheli), although these individuals were clearly sinapis.

Sinapis males have a distinctive white spot on the inside of the antennal club whereas this is brown or black for duponcheli. The white spot is a clear identifier of sinapis. However, it is my experience that sinapis females do not have this clear white spot of the males, being mostly brown on the inside of the antennal club (see 36948), so care must be taken not to assume sinapis females to be duponcheli.

Another reliable indicator is that for duponcheli the unf costa has dark scaling in the basal region which does not extend into the cell, whereas in sinapis it does.

The key feature for identifying duponcheli - but this is only applicable to the first (April-May) brood - is the classic duponcheli unh where it is almost completely dusted with green or grey scales in a very characteristic pattern. I have seen sinapis which are very heavily dusted with green/grey scales in a not dissimilar pattern. However, on studying the Natural History Museum archives of duponcheli, ALL specimens very clearly had the classic pattern and none were in any way intermediary between this and the normal sinapis pattern, i.e. duponcheli was unmistakeable. It was subsequently pointed out to me that the collectors of yore probably only retained those specimens that met the classic criteria, and may have discarded those that did not.

Second brood (July-August) duponcheli, as noted above, have virtually no grey scales and a pale yellow tinge; on this basis 6325 and 52197 could be identified as duponcheli, but the white antennal spot clearly says otherwise.

There is another differentiator only visible on the upperside: the duponcheli the upf vein 1 has a hump below the cell - see 7219 below - whereas the sinapis vein 1 is flat here and does not have the hump.

Duponcheli is a species with a distribution principally limited to the southern Balkans but with a limited separate population in the far south-east of France. I should add that I had never seen duponcheli for certain (one or two probable false alarms) until 2014, as this is a species quite scarce in Var, although rather less uncommon in the Alpes-de-Haute-Provence.

Some sinapis may actually be the recently-discovered Réal's Wood White (L. reali), a species so similar to sinapis that only an examination of the genitalia can tell them apart for certain. Reali, it was originally believed, flies in Ireland (but see below) but not in mainland Britain, and in certain discrete regions in Europe including much of the far east of France. In Ireland, sinapis flies only in the region around the Burren in western Ireland, while reali flies in the remainder of the country, and their distributions do not overlap.

There are some alleged external differences, notably that the unh post-discal band of reali grey scales is quite pronouncedly curved. Of the photographs on this page, not many have any significant degree of grey scaling, and of those that do, none seem particularly curved, and I cannot see any reason to assume that they are anything other than sinapis, although 12548 just might be reali.

However, nothing is ever simple in butterfly-land. Recent DNA studies in 2011 showed that a third species existed, the for-once accurately named Cryptic Wood White (L. juvernica) and it appears that the reali from Ireland are in fact juvernica. The distribution of juvernica extends across Europe and Asia and it has existed for some 70,000 years, much longer than sinapis and reali.

observations

a second brood male. The unh grey markings of the Var specimens are very light, and the general colouring underside very much yellower than as shown in T&L, and on this basis it looks very much like the illustration of the much rarer duponcheli, although I am fairly certain it is sinapis because the white tips of the antennae are clearly visible. This just serves to demonstrate how difficult it is to identify some species from (very good) illustrations in books; it often needs two or more indicators to be certain.

a first brood male, I suspect, based on its apparent taking salts and rather lighter dusting of unh grey scales.

another second brood male with a virtually unmarked unh, in an upright pose often adopted when taking salts from wet soil.

a first brood female, I think, based on the very heavy dusting of grey unh scales.

I was trying to get a lucky snap of the upperside of this slow-flying Leptidea upperside caught in flight. On closer inspection I began to wonder if it might be duponcheli for several reasons: the upperside is very white and the black upf apical marks are very small, both clues to duponcheli; the underside of the antennal tip shows no sign of white (which would indicate sinapis if 7219 is a male) although maybe the detail level is not good enough to be conclusive of this; most significantly, the upf vein 1 in the basal area shows a very clear "hump" (arrowed in the illustration below, but much clearer in the enlarged version) and this is considered to be definitive (if rarely seen in the wild) evidence of duponcheli; the sinapis vein is much flatter, and on this basis, I would tend to say 7219 is duponcheli, but further evidence (the unh of the first brood which flies in May-June has a characteristic pattern as noted above - this should/would be obvious in flight) is needed to be 100% certain.