title: Molecular phylogenies support homoplasy of multiple morphological characters used in the taxonomy of Heteroscleromorpha (Porifera: Demospongiae).
abstract: Sponge classification has long been based mainly on morphocladistic analyses but is now being greatly challenged by more than 12 years of accumulated analyses of molecular data analyses. The current study used phylogenetic hypotheses based on sequence data from 18S rRNA, 28S rRNA, and the CO1 barcoding fragment, combined with morphology to justify the resurrection of the order Axinellida Lévi, 1953. Axinellida occupies a key position in different morphologically derived topologies. The abandonment of Axinellida and the establishment of Halichondrida Vosmaer, 1887 sensu lato to contain Halichondriidae Gray, 1867, Axinellidae Carter, 1875, Bubaridae Topsent, 1894, Heteroxyidae Dendy, 1905, and a new family Dictyonellidae van Soest et al., 1990 was based on the conclusion that an axially condensed skeleton evolved independently in separate lineages in preference to the less parsimonious assumption that asters (star-shaped spicules), acanthostyles (club-shaped spicules with spines), and sigmata (C-shaped spicules) each evolved more than once. Our new molecular trees are congruent and contrast with the earlier, morphologically based, trees. The results show that axially condensed skeletons, asters, acanthostyles, and sigmata are all homoplasious characters. The unrecognized homoplasious nature of these characters explains much of the incongruence between molecular-based and morphology-based phylogenies. We use the molecular trees presented here as a basis for re-interpreting the morphological characters within Heteroscleromorpha. The implications for the classification of Heteroscleromorpha are discussed and a new order Biemnida ord. nov. is erected.
authors.affiliation: *School of Biological Sciences, MBC, 97 Lisburn Road, Queen's University, Belfast BT9 7BL, UK; National Systematics Laboratory, National Museum of Natural History, MRC-153, Smithsonian Institution, P.O. Box 37012, Washington, DC 20013-7012, USA; National Museums Northern Ireland, 153 Bangor Road, Holywood BT18 0EU, Northern Ireland, UK; Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA; School of Natural Science and Ryan Institute, National University of Ireland Galway, University Road, Galway, Ireland.
authors.forename: Christine C
authors.initials: CC
authors.lastname: Morrow
authors.forename: Niamh E
authors.initials: NE
authors.lastname: Redmond
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Picton
authors.forename: Robert W
authors.initials: RW
authors.lastname: Thacker
authors.forename: Allen G
authors.initials: AG
authors.lastname: Collins
authors.forename: Christine A
authors.initials: CA
authors.lastname: Maggs
authors.forename: Julia D
authors.initials: JD
authors.lastname: Sigwart
authors.forename: A Louise
authors.initials: AL
authors.lastname: Allcock
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D017931:DNA Primers / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D011161:Porifera / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D003576:Electron Transport Complex IV