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. In the systematics of organisms, maybe more than in other scientific fields, names tend to be unstable on the long run. As new hypotheses of relationships between groups arise, also new names are assigned to newly supposed monophyletic groups (clades, taxa). Such new names often make reference to older, well-established names. These references are in many cases forged by applying prefixes to the old, established name. One of those prefixes that has been used in these instances is 'Pan', the Ancient Greek word for “all”. This prefix has especially been used for coining names of groups which include fossils (then sometimes also called 'total group').
Carolin Haug and Joachim Tobias Haug