S8-1.2 Sunday, Jan. 6 New 18S rDNA Sequence Data Suggest Exciting New Hypotheses for Internal Relationships of Demospongiae (Phylum Porifera). REDMOND, NE*; MORROW, CC; THACKER, RW; DIAZ, MC; BOURY-ESNUALT, N; CáRDENAS, P; HAJDU, E; LôBO-HAJDU, G; PICTON, BE; COLLINS, AG; NMNH, Smithsonian Institution ; Queen’s University, Belfast, Northern Ireland; University of Alabama at Birmingham; Museo Marino de Margarita, Venezuela; Université d\'Aix-Marseille, France; Uppsala University, Sweden; Museu Nacional/Universidade Federal do Rio de Janeiro, Brazil; Universidade do Estado do Rio de Janeiro, Brazil; National Museums Northern Ireland, UK; NMNH, Smithsonian Institution email@example.com
The systematics of sponges (Porifera) is extremely difficult to decipher and constantly evolving. Here we present some exciting results on the phylogenetic relationships within Demospongiae based on 18S rRNA data. We add over 420 new nearly complete demosponge 18S sequences to approximately 180 existing sequences from GenBank. Our dataset includes over 35 genera that had not been included in molecular phylogenies to date, shedding new light on their familial affinities. We present several new hypotheses suggesting further revision and refinement of the emerging, more consensus-based, systematics of demosponges. Among numerous results are the following hypotheses: 1) within Myxospongia Chondrosia is sister to a monophyletic Verongida making the order Chondrosida paraphyletic; 2) within Keratosa, Dendroceratida is weakly supported as monophyletic, while Dictyoceratida has high support and is split into two highly supported clades, Spongiidae + Irciniidae + most Thorectidae and Dysideidae + remaining Thorectidae; 3) numerous lineages within Haploscleromorpha have undergone simplification of skeletal structure; 4) within Democlavia (=Heteroscleromorpha), nearly all of the independently derived clades of Morrow et al. 2012 are valid; and 5) freshwater Spongillida and “lithistid” Vetulinidae are sister groups with a close relationship to Scopalinidae.