The phylogeny of Arthrotardigrada

The order Arthrotardigrada, or water bears, constitutes a small group of 160 species of marine, microscopical invertebrates, within the phylum Tardigrada. Although the position of tardigrades in the Animal Kingdom has received much attention focusing on the metazoan phylogeny, the phylogenetic relationships within Tardigrada are mostly unresolved and prior to this thesis the phylogenetic relationships within Arthrotardigrada had not been investigated using modern cladistic methods. The long term objective for the international collaborative arthrotardigrade group is to produce the first numerical arthrotardigrade phylogeny based on combined morphological and molecular data. As a first step to reach this goal, detailed examinations of more than 100 species and thorough revisions of various arthrotardigrade genera were conducted to uncover their taxonomic diversity and morphological disparity, generating new characters for the morphological phylogenetic analyses and establishing monophyletic clades. In the present study, 11 species of arthrotardigrades are described in the genera Coronarctus, Parmursa, Florarctus, Renaudarctus, Megastygarctides, Mesostygarctus, Parastygarctus, Pseudostygarctus and Faroestygarctus nov. gen. belonging to the families Coronarctidae, Halechiniscidae (Euclavarctinae, Florarctinae), Renaudarctidae and Stygarctidae (Megastygarctidinae, Stygarctinae). In addition, diagnostic characters are given for 8 species of Archechiniscus and 3 species of Florarctinae nov. gen. Phylogenies of the subfamily Florarctinae and the superfamily Stygarctoidea are inferred based on morphological data and the phylogeny of Arthrotardigrada are inferred based on molecular data obtained during this study. The generated results are included in 9 original manuscripts including 6 published papers.