Glass sponges (Porifera, Hexactinellida) of the northern Mid-Atlantic Ridge

Abstract

Glass sponges (Hexactinellida) collected under the framework of the MAR-ECO project on the G.O. Sars cruise to the northern Mid-Atlantic Ridge, between the Azores and the Reykjanes Ridge, and on the 49th cruise of Akademik Mstislav Keldysh to the Charlie-Gibbs Fracture Zone are described. Fourteen species were identified in the material. This relatively rich fauna includes several novel findings, indicating that the hexactinellid fauna of the northern Mid-Atlantic Ridge is poorly investigated. One genus, Dictyaulus, has never before been reported from the Atlantic Ocean. Two species belonging to the genera Heterotella and Amphidiscella are new to science. Two other species, Rossella nodastrella Topsent, 1915 and Doconestes sessilis Topsent, 1928, have been collected just one other time. Finally, a probable new genus of Euplectellidae, which unfortunately cannot be adequately described because of how small the specimens are, is represented among these collections. A large portion of dead, rigid skeletons of Euretidae and spicule mats of Rossellidae are also reported but not described in detail. Representation of some genera in the Charlie-Gibbs Fracture Zone, coupled with recent observations from elsewhere along the Mid-Atlantic mountain chain, suggests that this fauna is as similar to those of the Indian Ocean and Indo-West Pacific as it is to West or East Atlantic faunas.

Keywords:

• Hexactinellida
• North Atlantic
• Porifera

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We greatly appreciate our Norwegian colleagues from the Museum of Zoology, University of Bergen, Dr J. Kongsrud and Dr A. Willassen, for their kind help during our investigation of their collections, all the participants and organizers of the expeditions that resulted in the collection of these materials, as well as the careful reviewers of our manuscript. A.G.C. gratefully acknowledges support from a grant from the A.P. Sloan Foundation to the Virginia Institute of Marine Science (M. Vecchione) as part of the MAR-ECO project. This work was an element of MAR-ECO, a field project under the Census of Marine Life programme.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark