Taxonomy of Farrea (Porifera, Hexactinellida, Hexactinosida) from the southwestern Atlantic, with description of a new species and a discussion on the recognition of subspecies in Porifera

The present study reports three species of Farrea Bowerbank, 1862 from Campos Basin (southwestern Atlantic): Farrea herdendorfi Duplessis and Reiswig, 2004, Farrea occa Bowerbank, 1862, and Farrea campossinus sp. nov. This is the first record of F. herdendorfi for the South Atlantic and only the second record of the species worldwide. Farrea occa is described and reported to form mass occurrences in the area’s sponge and coral banks, as seen in extensive video recording undertaken between 900 and 1100 m depth. The new species approaches Farrea foliascens Topsent, 1906 very closely, but differs in that its hooked anchorate clavules are much larger and the meshes of its dictyonal framework rather more irregular. Our thoughts on whether the proposed new species deserved species or subspecies rank led to an investigation on the usage of subspecies rank in Porifera. A historical overview, mainly contrasting Demospongiae and Hexactinellida is offered here. We concluded that no rule of thumb is readily made out from the comparative analysis of various authors’ taxonomic decisions. Until one such agreement is achieved, it appears to us that naming new subspecies should be objectively argued for, or better, totally avoided, as a useless further dimension to taxonomic uncertainty in poriferan classification.