title: Phylogenetic analyses of endoparasitic Acanthocephala based on mitochondrial genomes suggest secondary loss of sensory organs.
abstract: The metazoan taxon Syndermata (Monogononta, Bdelloidea, Seisonidea, Acanthocephala) comprises species with vastly different lifestyles. The focus of this study is on the phylogeny within the syndermatan subtaxon Acanthocephala (thorny-headed worms, obligate endoparasites). In order to investigate the controversially discussed phylogenetic relationships of acanthocephalan subtaxa we have sequenced the mitochondrial (mt) genomes of Echinorhynchus truttae (Palaeacanthocephala), Paratenuisentis ambiguus (Eoacanthocephala), Macracanthorhynchus hirudinaceus (Archiacanthocephala), and Philodina citrina (Bdelloidea). In doing so, we present the largest molecular phylogenetic dataset so far for this question comprising all major subgroups of Acanthocephala. Alongside with publicly available mt genome data of four additional syndermatans as well as 18 other lophotrochozoan (spiralian) taxa and one outgroup representative, the derived protein-coding sequences were used for Maximum Likelihood as well as Bayesian phylogenetic analyses. We achieved entirely congruent results, whereupon monophyletic Archiacanthocephala represent the sister taxon of a clade comprising Eoacanthocephala and monophyletic Palaeacanthocephala (Echinorhynchida). This topology suggests the secondary loss of lateral sensory organs (sensory pores) within Palaeacanthocephala and is further in line with the emergence of apical sensory organs in the stem lineage of Archiacanthocephala.
authors.affiliation: Institute of Molecular Genetics, Johannes Gutenberg-University Mainz, J-J Becherweg 30a, D-55099 Mainz, Germany. weber011@uni-mainz.de
authors.forename: Mathias
authors.initials: M
authors.lastname: Weber
authors.forename: Alexandra R
authors.initials: AR
authors.lastname: Wey-Fabrizius
authors.forename: Lars
authors.initials: L
authors.lastname: Podsiadlowski
authors.forename: Alexander
authors.initials: A
authors.lastname: Witek
authors.forename: Ralph O
authors.initials: RO
authors.lastname: Schill
authors.forename: László
authors.initials: L
authors.lastname: Sugár
authors.forename: Holger
authors.initials: H
authors.lastname: Herlyn
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankeln
mesh_terms: D000049:Acanthocephala / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D000818:Animals; D001499:Bayes Theorem; D005075:Biological Evolution; D004272:DNA, Mitochondrial / Q000235:genetics; D023061:Gene Order; D054629:Genome, Mitochondrial; D016013:Likelihood Functions; D010802:Phylogeny; D012679:Sense Organs; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial