First known free-living lithistid sponge

Lithistids, an informal grouping of demosponges, are sponges with skeletons built of articulated spicules. Typically they are found in deep waters, but off the Somali coast we discovered six species inhabiting sandy sea-bottom at a depth of 50 metres. Three of them are proposed as new. One, Microscleroderma magnum, was found living unattached—the first recorded free-living lithistid. The assemblage composition differs from that of African and Indian Ocean coasts, though some similarities to nearby regions are evident.

Figure: habitus of the studied sponges. A–C, I–J, Gastrophanella somaliensis sp. nov., D–H, Microscleroderma magnum sp. nov.