Meeting Abstract

S8-1.4  Sunday, Jan. 6  Molecular phylogenies support homoplasy of multiple morphological characters used in the taxonomy of Heteroscleromorpha (Porifera: Demospongiae) MORROW, C.C.*; REDMOND, N.E.; PICTON, B.E.; ALLCOCK, A.L.; SIGWART, J.D.; MAGGS, C.A.; Queen\’s University Belfast; NMNH, Smithsonian Institution ; National Museums Northern Ireland; Dept. of Zoology, Ryan Institute, National University of Ireland Galway; Queen\’s University Belfast; Queen\’s University Belfast christinemorrow@gmail.com

The most recent attempt to produce a stable classification of sponges was based solely on morphological characters (Systema Porifera Hooper & van Soest, 2002) and incorporated the cladistic analyses of van Soest et al., 1987 & 1990; de Weerdt, 1989 and Hooper, 1990 & 1991. The current study uses sequence data from 18S rDNA; 28S rDNA and CO1 barcoding fragment combined with morphology to justify the resurrection of Axinellida Levi, 1973. The abandonment of Axinellida and the establishment of Halichondrida sensu lato to contain Halichondriidae, Axinellidae, Heteroxyidae and a new family Dictyonellidae was based on the hypothesis that it was more parsimonious to assume that an axially condensed skeleton evolved independently in four separate lineages than to assume that asters (star shaped spicules); acanthostyles (club-shaped spicules with spines) and sigmata (C-shaped spicules) each evolved more than once (van Soest et al., 1990). Our resulting molecular trees are congruent and contrast with the morphology based trees of van Soest et al., 1990. The results show that axially condensed skeletons, asters, acanthostyles and sigmata are all homoplasious or alternatively that some may be ancestral but lost in certain lineages. We use the molecular trees presented here as a basis for re-interpreting the morphological characters within Heteroscleromorpha.