Desma-bearing sponges, also known as lithistids or rock sponges, are a group typical of bathyal environments throughout tropical and warm-temperate regions. In this study the lithistids collected in the course of the Harbor Branch Oceanographic Institute eastern Atlantic 1991 campaign to Madeira, Selvagens and the Canary Islands were identified and assigned to eight species, representing eight genera and five families. Several constitute new records for these islands and one is a new species of Isabella, a genus thus far only known from the Norfolk Ridge in New Caledonia, that is here described and illustrated. Some considerations are made in regards to the diversity and biogeographical affinities of the Atlanto-Mediterranean lithistid sponges.
