www.ukbutterflies.co.uk

Sorting through photographs of mine, I came across this one of a Gatekeeper. I would be interested to know whether anyone has a view as to whether it's ab. excessa or ab. crassiexcessa, or something else entirely. Any thoughts would be much appreciated,

Rob

Hello Rob ,
Nice find ,i think i,d lean towards AB;Tithonellus had i found it .............if not ,as you,ve suggested Excessa or post Excessa.
Take a look at "British Butterfly Abberations " website ...................a very useful tool .
Allan.W.

Looking at the 'official' description of both excessa and crassiexcessa there seems to be enough cross over for it to fit into either one tbh. The only difference seems to be that crassiexcessa mentions both upper and underside whereas excessa only the upperside is mentioned.

Tithonellus also seems to cross over with some, but does say the the extra ocelli are never pupiled so in this case I'd rule it out.

Unlike taxonomy between species, the world of abs. is prone to a fair bit of subjective decision making on the observers part.

https://www.ukbutterflies.co.uk/aberrat ... style=name

Thanks to both. My first thought was ab. tithonellus, in fact, but I ruled it out for the same reason - one of the spots has a white pupil. I only photographed the upper side unfortunately but I'll settle on crassiexcessa, I think, as it also mentions the "maybe unequal" additional spots.

I look forward to this season's Gatekeepers with renewed interest!