Key: Aedeagus is the phallus of the male
Thorn shield: this is one of the diagnostics and is a number of spikes comprising what is termed a thorn-shield. In similis it is supposed to be up to 100, although here it is over 100.
Gnathos: This supports the anal tube and its shape is another diagnostic
Sacculus: this forms the base of the valvae, which in themselves are 2 wing-like structures.
Vinculum: In Bryotrohas these often have a knee-cap shape and the lack of one in similis is another identifying feature
So to id it as similis, I counted the number of spikes in the thorn-shield, looked at the shape of the gnathos - in this case sharply bent and wider after the bend tapering to a point, the lack of a knee on the vinculum and finally the wing pattern of the adult moth. I used the key in MBGBI volume 4(2) plus an additional publication called The Genus Bryotropha in the Western Palearctic by Karsholt & Rutten.
The first image shows the parts with names, the second is the recent politella of Liz and the third, to help, is another politella from another county but in a shape that is similar to the similis, so it might be easier to relate them all.
Why are some backgrounds blue and others fawn? I choose what to make the background in the complex process of photographing microscopic parts and in some cases I feel that pale blue accentuates the features and in others fawn does the same. Rarely I will use a pale yellow.
|Bryotropha similis Ynys-hir - Ina Smith