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Is it worth pursuing? What should I be looking for? Is it the hairlets under the frontal bristles - they were not easy to count on this specimen, and I did think they could have been a bit meagre. I've got 4 Siphona from this site, all of which I think are S geniculata. I thought S cristata could be distinguished from S geniculata because S cristata does not have dorsal marginal bristles on tergite 2 and S geniculata (and this specimen) does?