Diversité des demosponges Tunisiennes

Abstract

A review of studies carried out until 2003 on sponge systematics, benthic bionomy and on Tunisian marine biodiversity, as well as recent reports, allowed us to draw up a list of Tunisian demosponges Demospongiae, Porifera) of 143 species, belonging to 65 genera, 37 families and 13 orders (including three sub-orders), not equitably distributed within the three Tunisian geographical regions: North, East and South. The southern one is the most rich in number of species and genera. Besides, the species are divided in three groups. The first one of 33 species, has a large geographical repartition from the North up to the South of Tunisia. The second one, of 37 species occurring in two regions at the same time (North and East, North and South or East and South). While the third group of 72 species, the most important one, has a geographical repartition restricted to one only of the three regions (northern region or the eastern region or the southern one). Furthermore, a Czekanowski's coefficient, weak and not so different from a region to an other, as well as the existence of a contingent of 72 species with a single regional occurrence, don't allow conclusions regarding the existence of a regional centre of species diffusion, but support the idea of regional specificity for the Tunisian demosponges stocks, mainly in the southern and northern region.