A new species of cyanobacterial symbiont from the marine sponge Chondrilla nucula

Partial 16s rDNA sequencing results indicate that the unicellular cyanobacterial symbionts of the sponge species Chondrilla nucula, from the Mediterranean Sea, and C. australiensis, from Australia, are the same, and comprise a unique species. This cyanobacterium belongs to the genus Synechococcus, and occurs in the surface tissues of these sponges, as demonstrated with Fluorescent In Situ Hybridization (FISH) using a sequence-specific DNA probe, and with Transmission Electron Microscopy (TEM). We propose the name Candidatus Synechococcus spongiarum sp. nov. for this symbiont. The cyanobacterial symbiont "Aphanocapsa feldmannii" (Fremy), hosted by the marine sponge Petrosia ficiformis from the Mediterranean Sea, is a separate, but closely related, species also belonging to the genus Synechococcus.