[Coral-List] Splitting Symbiodinium into multiple genera

[Todd LaJeunesse]

Subject: Splitting Symbiodinium into multiple genera


Dear colleagues of the coral-list serve,



We would like to bring your attention to our open access paper out in
Current Biology: “Systematic revision of Symbiodiniaceae highlights the
antiquity and diversity of coral endosymbionts.” (open access)



All of us working on reef corals and numerous other invertebrates are well
aware of the importance of their mutualisms with the dinoflagellate
micro-algae commonly referred to as zooxanthellae. With the application of
molecular techniques, it was recognized nearly 30 years ago that the
endosymbionts in the genus Symbiodinium constituted an extremely diverse
and divergent group. For all of this time, we have been referring to this
diversity with different terms that represent different levels of genetic
resolution, including clades, sub-clades, types, and strains. This peculiar
nomenclature can be confusing, especially to those outside the field, and
acts as a barrier to studying the group. In an effort to simplify and
modernize the systematics and taxonomy of coral/invertebrate zooxanthellae,
we have spent the last few years formally describing Symbiodinium species.



The new paper is a culmination of these efforts, serving as a systematic
revision that brings the formal taxonomy in line with our current
understanding of the evolutionary relationships among these organisms.
Using genetics and other data, we split the genus Symbiodinium into
multiple genera, naming seven of them and recognizing the existence of at
least 15. The new genera mostly correspond to the old clade designations.
For example, Clade B has become Breviolum, Clade C has become Cladocopium,
etc. You will note a correspondence between the first letter of each new
genus and its former clade designation. The original name Symbiodinium is
reserved only for members of the ancestral Clade A, and we suggest
referring to the entire group by its family name, Symbiodiniaceae. When
possible please avoid the overuse of "zooxanthellae," except as a
colloquial term, There are many kinds of “zooxanthellae” including groups
of unrelated dinoflagellates and diatoms.





Although the creation of new generic names will be disruptive, we feel it
is a necessary step that will ultimately improve the study of marine
symbioses. To ease the transition, we recommend that former clade and/or
ITS2 designations be included in the first mention of a given genus and/or
species, if one exists. Adopting such stylistic changes will ensure clear
links between past and present nomenclature when writing about new
findings. For those who are interested, the supplemental Taxonomic Summary
is a comprehensive resource that ties all the currently named species back
to their ITS2 types and other previous names in the literature (and
provides the full formal descriptions of each named genus).



In addition to these taxonomic changes, the paper also includes re-analysis
of molecular dating using new data that places the evolution of the family
Symbiodiniaceae well back to the Jurassic Period in the Mesozoic Era,
corresponding to the time when the major evolution and diversification of
modern reef corals began.



If you have any questions or comments, please do not hesitate to contact
us. Thank you.





Sincere regards,



Todd, John, Paul, Hae Jin, James, Christian, and Scott

-- 
Todd C. LaJeunesse PhD
Associate Professor
Department of Biology
327 Mueller Laboratory
Pennsylvania State University
University Park, PA 16802

WebSITE: http://www.personal.psu.edu/tcl3/index.html

Office: 814 863 2038
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