Whilst many spiders can be identified with "relative" ease using a low power binocular microscope with only one or two reference books and a small proportion can be identified in the field or from photographs, there are a number of groups within the spiders where the species are very similar and difficult to distinguish. PDF documents are available below, produced by experienced arachnologists, which aim to help all arachnologists to correctly identify the species with these groupings.

Below are links to the first selection of Difficult Species Crib Sheets (these are all PDFs and should open into a new window or tab):

• Identification of Porrhomma species (Linyphiidae)
• Identification of Tegenaria gigantea and T. saeva (Agelenidae)
• Identification of Zelotes apricorum and Z. subterraneus (Gnaphosidae)
• Identification of Alopecosa cuneata and A. pulverulenta (Lycosidae)
• Identification of Dysdera crocata and D. erythrina (Dysderidae)
• Identification of Clubiona neglecta and C. pseudoneglecta (Clubionidae)
• Identification of Clubiona rosserae (Clubionidae)
• Identification of Neon robustus and N. reticulatus (Salticidae)
• Identification of Tetragnatha extensa and Tetragnatha pinicola (Tetragnathidae)
• Identification of Bathyphantes gracilis and Bathyphantes parvulus (Linyphiidae)
• Identification of Entelecara acuminata and Entelecara congenera (Linyphiidae)
• Identification of Pelecopsis nemoralis and P. nemoralioides (Linyphiidae)
• Identification of Pocadicnemis pumila and P. juncea (Linyphiidae)

The intention is to add to these as more become available.