Phylomitogenomics bolsters the high-level classification of Demospongiae (phylum Porifera)

• DOI: 10.1371/journal.pone.0287281
• Publication Date: 2023-12-04T18:26:01Z
• Authors: Dennis V. Lavrov; Maria C. Diaz; Manuel Maldonado; Christine C. Morrow; Thierry Perez; Shirley A. Pomponi; Robert W. Thacker
• Keywords: Incertae sedis; Sister group

Class Demospongiae is the largest in phylum Porifera (Sponges) and encompasses nearly 8,000 accepted species three subclasses: Keratosa, Verongimorpha, Heteroscleromorpha. Subclass Heteroscleromorpha contains ∼90% of demosponge subdivided into 17 orders. The higher level classification demosponges underwent major revision as result decades molecular studies. However, because most previous work only utilized partial data from a small number nuclear mitochondrial (mt) genes, this scheme needs to be tested by larger datasets. Here we compiled mt dataset for 136 species-including 64 complete or six mt-genome sequences determined assembled study-and used it test phylogenetic relationships among general particular. We also investigated position Myceliospongia araneosa, highly unusual without spicules spongin fibers, currently classified incertae sedis, which were not available. Our results support previously inferred sister-group relationship between Keratosa + Verongimorpha suggest five main clades within Heteroscleromorpha: Clade C0 composed order Haplosclerida; C1 Scopalinida, Sphaerocladina, Spongillida; C2 Axinellida, Biemnida, Bubarida; C3 Tetractinellida; C4 Agelasida, Clionaida, Desmacellida, Merliida, Suberitida, Poecilosclerida, Polymastiida, Tethyida. these (C0(C1(C2(C3+C4)))). Analysis M. araneosa placed clade sister taxon skeletonized tetractinellids Microscleroderma sp. Leiodermatium Molecular clock analysis dated divergences Cambrian Early Silurian, origins heteroscleromorph orders middle Paleozoic, basal splits around Paleozoic Mesozoic transition. Overall, study are mostly congruent with Heteroscleromorpha, but add temporal perspective new resolution subclass.