PHYLOGENETIC RELATIONSHIPS WITHIN THE ONISCIDEA (CRUSTACEA, ISOPODA)

ABSTRACT Comparative anatomical investigations on the pleon of representatives of the taxa Ligiidae, Tylidae, Mesoniscidae, Synocheta, and Crinocheta have disclosed numerous character transformations within the Oniscidea. They are used, together with other anatomical characters, to reconstruct the phylogenetic-systematic relationships of the main groups of terrestrial isopods and to propose a modified classification. The cladistic analysis reveals a sister-group relationship between the Diplocheta (Ligiidae) and all other terrestrial isopods (new taxon Holoverticata). The Holoverticata split up into the new taxon Tylida (Tylidae) and the well-defined monophyletic taxon Orthogonopoda (Mesoniscidae+Synocheta+Crinocheta). Within the latter group, the Synocheta are assumed to represent the sister group of the Crinocheta.