Nuclear and mitochondrial phylogeny of Rossella (Hexactinellida: Lyssacinosida, Rossellidae): a species and a species flock in the Southern Ocean

Hexactinellida (glass sponges) are abundant and important components of Antarctic benthic communities. However, the relationships and systematics within the common genus Carter, 1872 (Lyssacinosida: Rossellidae), are unclear and in need of revision. The species content of this genus has changed dramatically over the years depending on the criteria used by the taxonomic authority consulted. was formerly regarded as a putatively monophyletic group distributed in the Southern Ocean and the North Atlantic. However, molecular phylogenetic analyses have shown that is restricted to the Southern Ocean, where it shows a circum-Antarctic and subantarctic distribution. Herein, we provide a molecular phylogenetic analysis of the genus , based on mitochondrial (16S rDNA and ) and nuclear (28S rDNA) markers. We corroborate the monophyly of and provide evidence supporting the existence of one species, namely Carter, 1872 and a species flock including specimens determined as Topsent, 1901, Topsent, 1901, Schulze and Kirkpatrick 1910, and (Kirkpatrick 1907).