Data from: Systematic revision of Symbiodiniaceae highlights the antiquity and diversity of coral endosymbionts

The advent of molecular data has transformed the science of organizing and
studying life on Earth. Genetics-based evidence provides fundamental
insights into the diversity, ecology, and origins of many biological
systems, including the mutualisms between metazoan hosts and their
micro-algal partners. A well-known example is the dinoflagellate
endosymbionts (“zooxanthellae”) that power the growth of stony corals and
coral reef ecosystems. Once assumed to encompass a single panmictic
species, genetic evidence has revealed a divergent and rich diversity
within the zooxanthella genus Symbiodinium. Despite decades of reporting
on the significance of this diversity, the formal systematics of these
eukaryotic microbes have not kept pace, and a major revision is long
overdue. With the consideration of molecular, morphological,
physiological, and ecological data, we propose that evolutionarily
divergent Symbiodinium “clades” are equivalent to genera in the family
Symbiodiniaceae, and we provide formal descriptions for seven of them.
Additionally, we recalibrate the molecular clock for the group and amend
the date for the earliest diversification of this family to the middle of
the Mesozoic Era (∼160 mya). This timing corresponds with the adaptive
radiation of analogs to modern shallow-water stony corals during the
Jurassic Period and connects the rise of these symbiotic dinoflagellates
with the emergence and evolutionary success of reef-building corals. This
improved framework acknowledges the Symbiodiniaceae’s long evolutionary
history while filling a pronounced taxonomic gap. Its adoption will
facilitate scientific dialog and future research on the physiology,
ecology, and evolution of these important micro-algae.