Proposal for a revised classification of the Demospongiae (Porifera)

Abstract

BackgroundDemospongiae is the largest sponge class including 81% of all living sponges with nearly 7,000 species worldwide. Systema Porifera (2002) was the result of a large international collaboration to update the Demospongiae higher taxa classification, essentially based on morphological data. Since then, an increasing number of molecular phylogenetic studies have considerably shaken this taxonomic framework, with numerous polyphyletic groups revealed or confirmed and new clades discovered. And yet, despite a few taxonomical changes, the overall framework of the Systema Porifera classification still stands and is used as it is by the scientific community. This has led to a widening phylogeny/classification gap which creates biases and inconsistencies for the many end-users of this classification and ultimately impedes our understanding of today’s marine ecosystems and evolutionary processes. In an attempt to bridge this phylogeny/classification gap, we propose to officially revise the higher taxa Demospongiae classification.DiscussionWe propose a revision of the Demospongiae higher taxa classification, essentially based on molecular data of the last ten years. We recommend the use of three subclasses: Verongimorpha, Keratosa and Heteroscleromorpha. We retain seven (Agelasida, Chondrosiida, Dendroceratida, Dictyoceratida, Haplosclerida, Poecilosclerida, Verongiida) of the 13 orders from Systema Porifera. We recommend the abandonment of five order names (Hadromerida, Halichondrida, Halisarcida, lithistids, Verticillitida) and resurrect or upgrade six order names (Axinellida, Merliida, Spongillida, Sphaerocladina, Suberitida, Tetractinellida). Finally, we create seven new orders (Bubarida, Desmacellida, Polymastiida, Scopalinida, Clionaida, Tethyida, Trachycladida). These added to the recently created orders (Biemnida and Chondrillida) make a total of 22 orders in the revised classification. We propose the abandonment of the haplosclerid and poecilosclerid suborders. The family content of each order is also revised.SummaryThe deletion of polyphyletic taxa, the use of resurrected or new names for new clades and the proposal of new family groupings will improve the comparability of studies in a wide range of scientific fields using sponges as their object of study. It is envisaged that this will lead to new and more meaningful evolutionary hypotheses for the end-users of the Demospongiae classification.

Carbohydrate-Carbohydrate Interactions Mediated by Sulfate Esters and Calcium Provide the Cell Adhesion Required for the Emergence of Early Metazoans

“…The striking supramolecular similarities with MAF clearly place DAF within the family of circular proteoglycans from sponges, the spongicans (15). This finding is consistent with the phylogenetic kinship of D. anchorata and M. prolifera; both of these species belong to the sponge order Ceractinomorpha (38).…”

Molecular phylogenies challenge the classification of Polymastiidae (Porifera, Demospongiae) based on morphology

“…Furthermore, in all molecular phylogenies of Demospongiae, Polymastiidae and other hadromerid families appeared in remote clades that seriously contradicted the traditional classification based on their morphological similarities. Very recently, based on the molecular data, Morrow and Cárdenas (2015) proposed abandoning the order Hadromerida and establishing five new orders for the former hadromerids, with the order Polymastiida including only one family, the Polymastiidae. This proposal highlights the importance of the polymastiids in the context of the deep phylogeny of demosponges.…”

Long-term turnover of the sponge fauna in Faro Lake (North-East Sicily, Mediterranean Sea)

“…The skeleton was processed by dissolution of the organic matter in boiling 65% nitric acid, suspended in alcohol and dropped onto slides for LM following standard methods to characterize microtraits of megascleres and microscleres. Taxonomic decisions, while keeping in mind the Porifera checklist of the Italian seas (Pansini & Longo 2008) and the Fauna d'Italia (Pansini et al 2011), refer to the World Porifera Database (Van Soest et al 2016) just updated after Morrow and Cárdenas (2015).…”