Description of Agelas cerebrum, a new species and re-description of A-dilatata (Porifera)

Recent collections of sponges made in the Bahamas revealed the occurrence o f two species of Agelas, which we could not assign to any of the currently recognised Agelas of the Western Atlantic. A comparison with literature rec ords and extensive collections of Agelas incorporated in several major muse a led us to conclude that several specimens belong to a species new to scie nce, Agelas cerebrum. This species differs from the repent ramose form of A . conifera (Schmidt, 1870) in possessing a massively erect tube shape, thin ner spicules and a higher number of whorls of spines. From the tubular form of A. conifera the new species differs in having much thicker tube walls w ith a system of convolutions and meandering grooves, and likewise differenc es in spicular dimensions. Agelas cerebrum differs from A. tubulata Lehnert & Van Soest, 1996 in having much thicker convoluted tubes and shorter spic ules. A single thickly flabellate specimen we assign to A. dilatata Duchass aing & Michelotti, 1864, a species so far considered incertae sedis, becaus e of compelling similarities with its original description and depiction. O ur specimen differs from A. clathrodes in having a smooth plate form rather than an irregularly pitted wall-shape, and in having much more heavily cor ed primary fibres. It differs from A. inaequalis Pulitzer-Finali, 1986 beca use it is not cup-shaped and the spicules have more whorls of spines. It ap pears closest to A. flabelli-formis (Carter, 1883) in shape and surface cha racteristics, but Carter's species forms very thin blades of 5 mm, whereas A. dilatata is 25-30 mm thick. Agelas flabelliformis has distinctly shorter and thinner spicules.