|The Purple Empire | ABERRATION iole|
It appears that the type specimen of iole held at the National History Museum is of a completely black individual, of which only this single, unique specimen has ever been collected. The issue then becomes, what do we call forms intermediate between the normal form and this all-black form? Contributors to the forum have varying views:
Photo by Robert Coleman, July 29th 2009
from Neil Hulme
I think it might be a nigrina versus obliterae situation, with slightly blurred and subjective boundaries. Technically it probably is lugenda, but if those spots became fainter and more diffuse it would, at some point, turn into iole. I'm not sure (and doubt) whether those spots ever TOTALLY disappear.
Photo by Matthew Oates, June 29th 2009, Straits Inclosure
from Ken Willmott
I have done a little research in my library and on Plate 1 of FW Frohawks aberrations book (1938) is an almost identical iris iole figure with a couple of white apical marks and an identical underside pattern as Matthew's photograph. Must say your underside photograph brought back memories of my Bookham iole, which, alas, I only saw through binoculars.
ab lugenda, Cabeau, Kent, Chattenden about 1870
from Piers Vigus
When iole was first described by Schiffermuller the description was of an utterly black butterfly with no white markings on the upperside or (and here's the important part) the underside. A specimen of iole rests in the BMNH.
lugenda was first described by Cabeau, and was of an iris specimen with forewings with three small white spots, hindwings with white transverse band completely absent, no light ante marginal band, and the eye in the anal angle pupilled bluish grey. The butterfly observed and photographed by MO fits this description perfectly.
The specimen on the frontispiece of Frohawk's Varieties cited by Ken Wilmot was famously mislabelled and has caused confusion ever since. This matter is discussed (somewhere) in Notes and Views.
Photo by Matthew Oates, as above
Heslop (Notes and Views 1964) himself addressed the issue thus:
At one time specimens showing any marked dimunition of white on the upperside were all referred to as iole Schiff. It is only in the last forty years or so that the practice has grown up of alluding to just the most extreme examples as iole and to all the intermediate ones as semi-iole....Those specimens having only one to four white spots on the forewing and no other white markings, are in Museum practice treated as ab lugenda Cabeau. And ab iolate (semi-iole) covers all specimens with substantial reduction of the white band.
Here we must observe that the relative figure in South (1906), appears to be referable as semi-iole, as understood, not iole.The figure on the frontispeice of Frohaw'ks "Varieties of British Butterflies" is apparently of Cabeau's lugenda.
Incidentally iole (lugenda?) was the last iris that Heslop took. A case of nunc dimittis, perhaps? And here's another little piece of iris trivia:
The female specimen featured above top left still exists. It was bred by A.J. Wightman from three larvae obtained from a Sussex wood in 1943. Originally requested by BMNH for preservation as larvae, upon being informed that they were no longer needed, Wightman bred out all three successfully, the iole figured emerging on 26th June 1943. It passed into the collection of Mr B.W.Adkin; and on the sale of his collection on 15th December 1948 it was bought by Henry Douglas Bessemer, a chartered accountant and keen collector.
Bessemer was already in possession of the only known full iole, the one which featured in Edward Newman's book. This insect was taken by Mr F Bond in Monkswood, and later it passed into the collection of Mr Sidney Webb. On the sale of the Webb collection in 1919, it was acquired by Mr P.M. Bright, whose collection was subsequently auctioned on 9th April 1942, when Bessemer purchased it.
The Bessemer collection, which was regarded as the UK's foremost private assemblage, was bequeathed to BNHM upon his death in 1968. The Museum also holds a collection of his manuscripts, including details of collecting data and prices paid for purchased specimens.