Diversity and biogeographic connections of sponges (Porifera, Poecilosclerida) from the southern Southwest Atlantic Ocean

Abstract

In this study, we assessed the diversity and distribution of sponges of the Order Poecilosclerida from the Burdwood Bank (BB), including the Namuncurá–Burdwood Bank Marine Protected Areas I and II, considering samples collected during two expeditions onboard the RV ARA “Puerto Deseado” in 2016 and 2017. Additionally, a comparative analysis of species richness and composition between BB and adjacent regions in Patagonia (Tierra del Fuego, Malvinas/Falkland Islands) and the Scotia Arc (South Georgias and South Orkney Islands) was made, employing information from bibliographic sources. A total of 53 species were recorded at BB, including 44 species recorded during the present study and 9 other older records from bibliographic sources. These results doubled the known richness of sponges of this order for the region and provided the most complete and updated checklist. Furthermore, new records and updated information on the distributional and bathymetric ranges of Amphilectus fimbriatus, Amphilectus rugosus, Clathria (Clathria) microxa, Guitarra sigmatifera, Iophon roseum, Lissodendoryx (Ectyodoryx) antarctica, Lissodendoryx (E.) diegoramirezensis, Lissodendoryx (E.) patagonica, Mycale (Carmia) gaussiana, Myxilla (Myxilla) basimucronata, and Stelodoryx argentinae are here provided. Poecilosclerida richness at BB was similar to that found in the Malvinas/Falkland Islands and South Georgias Is., with species composition being more similar among these areas than to Tierra del Fuego (TF). These findings significantly enhance the knowledge of sponge diversity in the region and highlight the relevance of the BB and their MPAs as a hotspot of diversity in the SW Atlantic Ocean.