Celtodoryx Girardae Gen. Nov Sp Nov., A New Sponge Species (Poecilosclerida : Demospongiae) Invading The Gulf Of Morbihan (North East Atlantic, France)

Celtodoryx girardae is described as new species and new genus. The new genus has clear relationships with several genera of the Coelosphaeridae. The choanosomal skeleton is a plumoreticulation of anisostrongyles or anisotylotes, with ectosomal tylotes, all megascleres bearing terminal spines. The microscleres belong to three types, arcuate isochelae of two sizes and oxychaetes. This sponge was sighted for the first time in the Ria of Etel (1996) and then in the Gulf of Morbihan (1999) (Brittany). Since then, the sponge, which seems to have fast spread dynamics, has become very abundant with tens of large specimens. On the basis of several criteria, this sponge is thought to be an introduced species: (i) it is new to the area; (ii) its distribution is rather localized; (iii) its dispersion from the first localised station follows a perceptible pattern; (iv) it has a strong tendency to proliferate; (v) there is a potential introduction source (oyster farms). The sponge is a successful competitor overgrowing other sessile invertebrates such as sea fans and other sponges.