Tanaidacean phylogeny - the second step: the basal paratanaoidean families (Crustacea: Malacostraca)

Abstract

Phylogenetic relationships between the basal (or less derived) families in the tanaidacean superorder Paratanaoidea are examined and their monophyly tested using evidence derived from external morphology. With the genus Zeuxoides from the superfamily Tanaidoidea as outgroup, monophyly is confi rmed for the Paratanaidae, Pseudotanaidae, Pseudozeuxidae, and Typhlotanaidae. The subfamily Teleotanainae is raised to family status to accommodate the genus Teleotanais. The monophyly of Leptocheliidae s.str. is accepted but several taxa are not included, neither is monophyly verifi ed for Heterotanainae and Leptocheliinae. Nototanaidae appears to be polyphyletic and is split into Nototanaidae s.str. and Tanaissuidae fam. nov. Cryptocopidae is recognized but with exclusion of the Iungentitanainae; otherwise, this family is left for later analysis, including more derived taxa. Protanaissus, Leptochelia, Pseudoleptochelia and Pseudonototanais all appear to be non-monophyletic and will need revisions, while Antiplotanais, Grallatotanais, Metatanais, and Tangalooma are considered ‘fl oating’ taxa, albeit close to existing family-level clades. Initial attempts to include the derived tanaidacean families proved inconclusive and this suggests that limited phylogenetic analyses of the Paratanaoidea are necessary. We here suggest a revised method – the ‘Restricted taxa analysis’ – for resolving diffi cult datasets of the ‘many-taxa-few-characters’ type. This study should be regarded as a platform for more comprehensive analyses and systematic conclusions for the Tanaidacea.