Morphology and Phylogeny of Scrippsiella trochoidea (Dinophyceae) a potentially harmful bloom forming species isolated from the sediments of Iran’s south coast



cells and resting cysts of the species Scrippsiella
trochoidea are regular and dominant components of the dinoflagellate flora
of coastal marine waters and sediments around the world. This species is a
common harmful bloom forming species in coastal waters. In this study, for the
first time cyst of S. trochoidea were isolated from the sediments
of southeast coast of Iran. Five strains from
the germination of a single cyst belonged to S. trochoidea. In order to confirm
identification of the species an excystment and encystment experiment, cyst and
germinated cell morphology and plate pattern by light and electron microscopy (SEM)
have been described. The nucleotide sequences of two highly diverse regions,
the rDNA-ITS 1,2 and 5.8S-rDNA have been sequenced for all strains. Homologous
sequences from GenBank with five Iranian strains were compared to find their
phylogenetic relationship. Both NJ and MP phylogenetic and morphological
analysis showed five strains of S. trochoidea from Iran were clustered
with previously described S. trochoidea and Calciodinellum levantinum
species, and its closest relationship was with Scrippsiella sp. strain
with a 1.2-1.4% sequence divergence. Results
indicate that molecular studies of rDNA if combined with morphological cyst and
vegetative cells could be a valuable approach to identification and taxonomy of
calciodinelloideae dinoflagellate.