SPONGES WITHOUT SKELETON - A NEW MEDITERRANEAN GENUS OF HOMOSCLEROMORPHA (PORIFERA, DEMOSPONGIAE)

A new genus of aspiculate homoscleromorph, Pseudocorticium, is describ ed along with the new species P. jarrei found in a littoral cave locat ed in the western Mediterranean Sea (France). The anatomy and cell com position are described and compared to that of species of the other ho moscleromorph genus without skeleton, Oscarella, and to genera with sk eleton, Corticium and Plakina. The new sponge differs from Oscarella i n its morphology, anatomy, and cytology. An emended definition of the genus Oscarella is proposed. Anatomical and cytological characters car ry a high informative content and should be described for a greater nu mber of sponge species.