Symbiodinium glynnii sp. nov., a species of stress-tolerant symbiotic dinoflagellates from pocilloporid and montiporid corals in the Pacific Ocean

A formal Symbiodinium species taxonomy enhances understanding of the physiology and ecology of coral-dinoflagellate symbioses. Here we formally define a new species of stress tolerant Symbiodinium in Clade D, Symbiodinium glynnii sp. nov. This species exhibits high host specificity for members of the stony coral genus Pocillopora in the Pacific Ocean and can also be found in symbiosis with the coral genera Seriatopora and Montipora. Symbiodinium glynnii is especially common in the Eastern Tropical and subtropical Pacific, where Pocillopora is abundant and ecologically important. While S. glynnii is evolutionarily closely related to Symbiodinium trenchii, a combination of multilocus genetic data including rDNA, chloroplast (psbA), and single copy nuclear microsatellites, as well as differences in ecology (host associations), morphology (cell size), and ultrastructure (chromosome size), identify S. glynnii as distinct from S. trenchii and other Clade D species. Finally we use these data to parameterize a provisional classification and regression model to show how closely related species are recognized by integrating multiple sources of evidence.