White-spotted Spring Jewel Eriocrania unimaculella

Originally given the vernacular name White-spot Purple.

This species is grade 2 which means it should be possible to identify from good quality photos, but in my opinion there is plenty of scope for error. In theory this species differs from the other similar Eriocrania in that the tornal spot is silver not gold, but I don't believe this is as simple as it sounds. I have previously caught an Eriocrania sangii which, when examined through a hand lens in the field, I was convinced had a silver tornal spot and would therefore be unimaculella. When I later examined its hindwing I discovered that the discal scales were sparse and hair-like, ruling out unimaculella. Upon closer examination I could see gold colour in the tornal spot, though the extent of this varied according to the angle and light. In contrast the unimaculella below clearly showed a golden element to its tornal spot (albeit a more silvery-gold colour than the gold elsewhere in its wing), leading me to conclude that it could not be unimaculella until I examined its hindwing and genitalia.

In the field and under the microscope this showed a clear golden hue to its tornal spot, leading me to suppose it would most likely prove to be the common early-flying species, Eriocrania semipurpurella or Eriocrania sangii. However both of those species show narrow hair-like scales in the centre of the hindwing and when I examined this I could see that the scales were not like that. They were slightly more elongate and less dense than the scales at the apex of the hindwing, but nowhere near narrow enough to be described as hair-like. Comparing with hindwing photos I'd taken of previous semipurpurella and sangii I was confident it could not be either of those species. Even then I was surprised to find that the genitalia confirmed that it was in fact unimaculella despite its golden-tinted tornal spot.

male White-spotted Spring Jewel Eriocrania unimaculella showing hindwing (including close-ups of apex and discal area) and genitalia, Ling Plantation, North Elmham (Norfolk, UK), 6th April 2024