Taxonomy of Porifera

Although sponges are one of the major components of littoral ecosystems, their systematics obviously lags behind that of the majority of other groups of marine invertebrates. Also the evolutionary trends in these most primitive of the Metazoans are poorly understood. The confused state of their taxonomy and the difficulties with their identification prevent their use in ecological studies. The emphasis of interest presently seems to have shifted towards chemistry, but many of the hundreds of interesting chemicals recently described in sponges pro­ bably have been found in mistakenly or imprecisely identified animals. This situ­ ation will become worse in the next few years, when a number of experts will retire and will not be replaced by new ones, owing to the difficulties that the science of systematics is facing in most countries - as exemplified during this meeting by an informal discussion on the endangered future of European Museums. Under these circumstances, it is the responsability of present sponge taxono­ mists to leave a less confused state and tools such as simple fauna or computerized data bases to generations following. These tools do not exist even in one of the best studied areas, the North-Eastern Atlantic (including the Mediterranean Sea).

Contenu

Calcareous sponges collected by N.O. Thalassa on the continental margin of the Bay of Biscaye: I. Calcinea.- The Polymastia species (Demosponges, Hadromerida) of the Atlantic Area.- Distinctive characters within the order Petrosida (=Nepheliospon- gida).- Anisochelae analysis and taxonomy of the genus Mycale Gray (Demo- spongiae).- An enzymatic technique for the separation of spicules from alcohol- preserved sponge tissue.- Skeletal variation in embryo-containing specimens of Haliclona rosea (Bowerbank) from Anglesey, North Wales.- The Haplosclerid sponge fauna of Banyuls-sur-mer (Mediterranean), with the description of a new species.- Littoral Demosponges from the banks of the Strait of Sicily and the Alboran Sea.- Tetillidae (Spirophorida, Porifera): A taxonomic reevaluation.- A study of the genus Tethya (Porifera, Demospongiae) and new perspectives in sponge systematics.- Phylogenetic exercises with monophyletic groups of sponges.- The use of electrophoresis in sponge taxonomy.- The calcium carbonate spherules of Hemimycale columella (Demo- sponges, Poecilosclerida) and their taxonomic value.- Some remarks on the Mediterranean species of the genus Aplysina (Demospongiae, Verongida).- Sexual reproduction, larval morphology and behaviour in Demosponges from the South-West of the Netherlands.- A review of North-Eastern Atlantic Hemigellius (Niphatidae, Hap- losclerida).- Participants in the N.A.T.O. workshop (Observers*).