Species delimitation in the sailfin blenny (Emblemaria pandionis) reveals cryptic endemic species diversity in the Greater Caribbean and Gulf of Mexico

Life history characteristics of cryptobenthic reef fishes (CRFs), such as their fast growth and reproductive rates, near-shore larval retention and high turnover, predispose these species to rapid diversification and cryptic speciation. This may be particularly true for isolated CRF populations. The sailfin blenny, Emblemaria pandionis , is widespread throughout the Caribbean and is found on the reefs of the Flower Garden Banks, an isolated reef system in the NW Gulf of Mexico. Using DNA barcoding and multi-locus delimitation, we show that E. pandionis is a species complex comprised of at least four distinct taxonomic units in the Caribbean, one at the Flower Garden Banks, a second in eastern Florida, a third in the central Caribbean and a fourth in Curaçao. The phylogenetic relationships within the E. pandionis species complex are defined by well-established phylogeographic barriers to gene flow in the Caribbean. Populations of E. pandionis from eastern Florida are genetically distinct from populations found in the Bahamas, highlighting the role of the Florida Strait as a strong barrier to gene flow and populations in Curaçao are deeply divergent from all other populations sampled in the Caribbean. Results from this study highlight the roles of isolated reefs and ocean currents in the speciation of cryptobenthic reef fishes.