Macroscopic characteristics facilitate identification of common Antarctic glass sponges (Porifera, Hexactinellida, Rossellidae)

• Published in: Polar Biology
• Main Authors: Federwisch, Luisa, Janussen, Dorte, Richter, Claudio
• Other Authors: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Deutsche Forschungsgemeinschaft
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2020
• Subjects: General Agricultural and Biological Sciences; Antarctic; The Antarctic; Weddell; Weddell Sea; Antarc*; Antarctica; Polar Biology; Glass sponges
• Online Access: http://dx.doi.org/10.1007/s00300-019-02612-2; http://link.springer.com/content/pdf/10.1007/s00300-019-02612-2.pdf; http://link.springer.com/article/10.1007/s00300-019-02612-2/fulltext.html

Abstract Glass sponges (Porifera, Hexactinellida) are conspicuous habitat-forming members of many Antarctic shelf communities. Despite their ecological importance, in-situ species identification remains problematic as it is traditionally based on microscopic analysis of spicules. External morphological features, in contrast, have largely been disregarded, so that different species have been mislabeled or lumped together when their identification was based on image material. In this paper, we provide a straight-forward guideline for in-situ identification of the most common rossellid sponges of the Antarctic shelf based on macroscopic characteristics. To determine diagnostic macroscopic characteristics of Anoxycalyx (Scolymastra) joubini and eight Rossella species, we combined examination of trawl-collected specimens, previous species descriptions and in-situ image material from the eastern Weddell Sea. Our study revealed that the smooth-walled species A. joubini , R. nuda and R. vanhoeffeni , previously often mixed up, can be distinguished by the form of their basal spicule tuft, their surface structure and their overall body form. The previously synonymized species R. racovitzae and R. podagrosa can be distinguished by their markedly different habitus. Based on our results, the so-called ‘ R. racovitzae budding type’ in fact refers to R. podagrosa which occurs regularly in the eastern Weddell Sea. The species R. villosa , R. levis , R. fibulata and R. antarctica can be distinguished by the appearance of their conules, protruding spicules and overall body form. We conclude that macroscopic characteristics are helpful means for identification of Antarctic rossellid sponge species. This approach enables species-specific quantitative studies of Antarctic glass sponge grounds based on increasingly used non-invasive imaging technology.