Relationships Within Eumalacostracan Crustacea

Abstract

A cladistic analysis was performed on 20 constituent higher taxa within the Eumalacostraca based on 31 characters of external anatomy. Variants of the most parsimonious scheme are presented, and the effects of tolerating different levels of uncertainty are evaluated. It is concluded that: 1) while the basic outline of Calman's (1904) taxonomy of Eumalacostraca might be utilized, the arrangement within peracarids postulated by Siewing (1956) cannot be maintained; 2) the Baupläne approach of Schram (1981) has some merit and some of the controversial higher taxonomic groupings of eumalacostracan "orders" originally indicated by that method are vindicated; 3) the idea that the carapace is a derived feature within eumalacostracans, advanced by dahl (1983), can be maintained only if a higher level of homoplasy is tolerated; 4) the concept of a taxon Mysidacea seems best abandoned.