Morphological and molecular characterization of free-living Symbiodinium natans-clade A (Dinophyceae) from La Paz Bay, Gulf of California

The genus Symbiodinium is a group of mostly endosymbiotic dinoflagellates, commonly known as zooxanthellae, that live associated with invertebrates and marine protists. The aim of the present study was the morphological and molecular identification of two strains of Symbiodiniales (SNCETMAR-1 and SNCETMAR-2) isolated from the anemone Actinostella sp. from La Paz Bay, Gulf of California. Identification was performed from cultures using photonic microscopy, including epifluorescence and scanning electron microscopy. A sequence of the SNCETMAR-2 strain was obtained from the 28S rDNA region. The combination of methods allowed the identification of the strains as Symbiodinium natans-clade A. This taxon is a group of free-living organisms, which facilitated the cultivation of the strains in the laboratory. The life cycle of this group presented 2 phases, a mobile phase and an immobile phase in the coccoid state, this being the last stage where sexual and asexual division occurred. This study expands the reports of clade A of the Symbiodiniaceae family in the Gulf of California, providing valuable information for its cultivation, identification and phylogenetic analysis