Vibrio is a diverse genus of marine-associated bacteria with at least 74 species and more expected as additional marine ecospheres are interrogated. This report describes a phylogenetic reconstruction of Vibrio isolates derived from one such unique ecosystem, marine sponges (Phylum Porifera) collected from depths of 150 to 1242 feet. 16S rRNA gene sequencing along with molecular typing of 16S–23S rRNA intergenic spacer regions clustered many sponge-associated Vibrio (spp) with current known species. That is, several benthic Vibrio species commensal with Porifera sponges seemed genetically linked to vibrios associated with coastal or shallow-water communities, signalling a panmictic population structure among seemingly ecologically disparate strains. Conversely, phylogenetic analysis provided evidence for at least two novel Vibrio speciation events within this specific sponge microcosm. Collectively, these findings earmark this still relatively unknown environment as a bastion of taxonomic and phylogenetic variability for the genus and probably other bacterial taxa.