The Ambiguous Use of the Prefix 'Pan' in Arthropod Systematics

'Pancrustacea' and 'Panarthropoda' are commonly used terms in arthropod systematics. Yet, both terms suffer from a severe shortcoming: they are not equivalent to any possible pan-monophylum concept applied to (any form of) 'Crustacea' or 'Arthropoda'. Therefore, both terms lack precision and can refer to quite different monophyletic groups. With this they do not provide the precision of alternative names for similar groupings, which also allow to express certain specific relationships, such as Crustacea sensu lato, Tetraconata or Arthropoda sensu lato. We emphasise the importance of unambiguous group names in order to provide a precise scientific communication.