id difficulty for Mermessus trilobatus
Identification difficulty rating=5
Even the most expert of recorders should seek a second opinion or the species is so rare that we would want confirmation by a national expert even if relatively easy to recognise. Voucher specimen of adult required to be examined by national expert.
Males and females may present different identification difficulty in spiders. These identification ratings are based on the most difficult identification. New species may become recognised or become part of the British fauna e.g. from Europe, so identification should be made with the awareness that this is a possibility and that confirmation may be needed in the form of a voucher specimen.