Genetics and Morphology Characterize the Dinoflagellate Symbiodinium voratum, n. sp., (Dinophyceae) as the Sole Representative of Symbiodinium Clade E. (30th November 2013)

• Record Type: Journal Article
• Authors: Jeong, Hae Jin; Lee, Sung Yeon; Kang, Nam Seon; Yoo, Yeong Du; Lim, An Suk; Lee, Moo Joon; Kim, Hyung Seop; Yih, Wonho; Yamashita, Hiroshi; LaJeunesse, Todd C.
• Is Part Of: Journal of eukaryotic microbiology. Volume 61:Number 1(2014:Jan./Feb.)
• Page Start: 75
• Page End: 94
• Publication Date: 2013-11-30
• Subjects: Protista -- Periodicals; Eukaryotic cells -- Periodicals; Microbiology -- Periodicals; 579.05
• DOI: 10.1111/jeu.12088
• Languages: English
• ISSNs: 1066-5234

Abstract

<abstract abstract-type="main" id="jeu12088-abs-0001"> <title>Abstract</title> <p>Dinoflagellates in the genus <italic>Symbiodinium</italic> are ubiquitous in shallow marine habitats where they commonly exist in symbiosis with cnidarians. Attempts to culture them often retrieve isolates that may not be symbiotic, but instead exist as free‐living species. In particular, cultures of <italic>Symbiodinium</italic> clade E obtained from temperate environments were recently shown to feed phagotrophically on bacteria and microalgae. Genetic, behavioral, and morphological evidence indicate that strains of clade E obtained from the northwestern, southwestern, and northeastern temperate Pacific Ocean as well as the Mediterranean Sea constitute a single species: <italic>Symbiodinium voratum</italic> n. sp. Chloroplast ribosomal 23S and mitochondrial cytochrome <italic>b</italic> nucleotide sequences were the same for all isolates. The D1/D2 domains of nuclear ribosomal DNA were identical among Western Pacific strains, but single nucleotide substitutions differentiated isolates from California (USA) and Spain. Phylogenetic analyses demonstrated that <italic>S. voratum</italic> is well‐separated evolutionarily from other <italic>Symbiodinium</italic> spp. The motile, or mastigote, cells from different cultures were morphologically similar when observed using light, scanning, and transmission electron microscopy; and the first complete Kofoidian plate formula for a <italic>Symbiodinium</italic> sp. was characterized. As the largest of known <italic>Symbiodinium</italic> spp., the average coccoid cell diameters measured among cultured isolates ranged between 12.2 (± 0.2 SE) and 13.3 (± 0.2 SE) μm. Unique among species in the genus, a high proportion (approximately 10–20%) of cells remain motile in culture during the dark cycle. Although <italic>S. voratum</italic> occurs on surfaces of various substrates and is potentially common in the plankton of coastal areas, it may be incapable of forming stable mutualistic symbioses.</p> </abstract>