SCRIPPSIELLA-VELELLAE SP-NOV (PERIDINIALES) AND GLOEODINIUM-VISCUM SP-NOV (PHYTODINIALES), DINOFLAGELLATE SYMBIONTS OF 2 HYDROZOANS (CNIDARIA)

The alga symbiotic with the ''By the Wind Sailor'' Velella velella L. (Hydrozoa, Chondrophora) collected off the coast of California, and the alga symbiotic with the hydrocoral Millepora dichotoma Forskal (Hydrozoa, Milleporina) from the Gulf of Aqaba, were isolated and brought into unialgal, axenic culture. Based on light microscopy and ultrastructural analyses by transmission and scanning electron microscopy, the algal population from V. velella is described as Scrippsiella velellae sp. nov. (Peridiniales). The algal population from the dark morph of M. dichotoma is described as Gloeodinium viscum sp. nov. (Phytodiniales). These are the first descriptions of symbiotic dinoflagellates belonging to the orders Peridiniales and Phytodiniales. When viewed with descriptions of symbiotic dinoflagellates belonging to the Prorocentrales and Gymnodiniales, the evidence currently points to seven genera in four orders of dinoflagellates having representatives that have entered a symbiotic mode of existence.