Biogeography of the marine actinomycete <i>Salinispora</i>

Summary Marine actinomycetes belonging to the genus Salinispora were cultured from marine sediments collected at six geographically distinct locations. Detailed phylogenetic analyses of both 16S rRNA and gyrB gene sequences reveal that this genus is comprised of three distinct but closely related clades corresponding to the species Salinispora tropica , Salinispora arenicola and a third species for which the name ‘ Salinispora pacifica ’ is proposed. Salinispora arenicola was cultured from all locations sampled and provides clear evidence for the cosmopolitan distribution of an individual bacterial species. The co‐occurrence of S. arenicola with S. tropica and S. pacifica suggests that ecological differentiation as opposed to geographical isolation is driving speciation within the genus. Al