Protosuberites denhartogi spec. nov., a new name for European ‘Prosuberites epiphytum’ (Demospongiae, Hadromerida)

The common NE Atlantic sponge species hitherto known under the name Prosuberites epiphytum (Lamarck, 1814), is differentiated from the South Australian type and other regional specimens. Spicule size and form, although generally similar, are subtly different. Australian P. epiphytum apparently persistently overgrow the thallus of algae, possibly as part of a symbiotic association, and this is not known for European specimens. In view of these facts and taking into account the disjunct distribution, it is proposed to assign the NE Atlantic populations to a new species. The genus Prosuberites has been restricted recently to species with single long tylostyles with heads embedded in a basal spongin plate, and both P. epiphytum and the new species do not conform to this definition. They are here assigned to Protosuberites Schwartschewsky, 1905. The new species is named Protosuberites denhartogi spec. nov. in honour of J.C. den Hartog.