Major discrepancy between phylogenetic hypotheses based on molecular and morphological criteria within the Order Haplosclerida (Phylum Porifera: Class Demospongiae)

Taxonomy within the sponge Order Haplosclerida remains somewhat contentious. Both morphology and biochemistry have been employed to help unravel the relationships of the Order with limited results perhaps because of the small number of reliable characters. We employed phylogenetic analysis of 750 base pairs of the 5′ end of the 28S rRNA gene to study relationships between 20 taxa within the Order. While preliminary (low number of taxa, one gene region) results suggested strong discrepancy to former phylogenies, there was no support for the monophyly of the Order and almost all morphologically defined genera appeared to be polyphyletic.