Forgive me a little indulgence. Since my sighting of an almost black aberration of Iris, I have been improving my understanding of the history of Iris aberration classification and the mythical ab. Iole. I was first struck by his strikingly jet black appearance. He was so dark that it was easy to track him even in flight as he flew up into the oaks and returned to his puddle. My first instinct was lugenda. However, aberrations like lugenda are described only in terms of absence or presence of white markings. This specimen clearly has a strikingly different ground colour. The photographs all look extremely dark.
I looked carefully at the cover of Frohawk's "Varieties of British Butterflies" and noted that this specimen with two upper wing clear white spots was very close to the Cotgrave specimen. This specimen has since been classified as ab. beroe. However, there is no doubt that there is the presence of a third faint white spot on the forewing on the Cotgrave aberration.
The ground colour of the upper side strongly black like the crow with a strong bluish reflection. Forewings with only two white spots, the apical and second marginal, the third is absent or almost so. Hindwing's with no trace of the transverse band, only some hairs of bluish grey. The anal eye is not pupilled.
Ab. Corax - am I right? - Comments please!