DESCRIPTION OF A NEW GENUS OF PFIESTERIA-LIKE DINOFLAGELLATE, LUCIELLA GEN. NOV. (DINOPHYCEAE), INCLUDING TWO NEW SPECIES: LUCIELLA MASANENSIS SP. NOV. AND LUCIELLA ATLANTIS SP. NOV. 1 Patrice L. Mason 2 Virginia Institute of Marine Science, The College of William and Mary, PO Box 1346, Gloucester Point, Virginia 23062-1346, USA R. Wayne Litaker Center for Coastal Fisheries and Habitat Research, National Ocean Service, NOAA, 101 Pivers Island Rd., Beaufort, North Carolina 28516-9722, USA Hae Jin Jeong, Jeong Hyun Ha School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea Kimberly S. Reece, Nancy A. Stokes Virginia Institute of Marine Science, The College of William and Mary, PO Box 1346, Gloucester Point, Virginia 23062-1346, USA Jae Yeon Park Research Institute of Oceanography, College of Natural Sciences, Seoul National University, Seoul 151-742, Korea Karen A. Steidinger Florida Institute of Oceanography ⁄ Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 100 Eighth Avenue SE, St. Petersburg, Florida 33701-5020, USA Mark W. Vandersea, Steve Kibler, Patricia A. Tester Center for Coastal Fisheries and Habitat Research, National Ocean Service, NOAA, 101 Pivers Island Rd., Beaufort, North Carolina 28516-9722, USA and Wolfgang K. Vogelbein Virginia Institute of Marine Science, The College of William and Mary, P.O. Box 1346, Gloucester Point, Virginia 23062-1346, USA A new genus of Pfiesteria-like heterotrophic dino- flagellate, Luciella gen. nov., and two new species, Luciella masanensis sp. nov. and Luciella atlantis sp. nov., are described. These species commonly occur with other small (<20 lm) heterotrophic and mixo- trophic dinoflagellates in estuaries from Florida to Maryland and the southern coast of Korea, suggest- ing a possible global distribution. An SEM analysis indicates that members of the genus Luciella have the enhanced Kofoidian plate formula of Po, cp, X, 4¢, 2a, 6¢¢, 6c, PC, 5+s, 5¢¢¢, 0p, and 2¢¢¢¢. The two four-sided anterior intercalary plates are diamond shaped. The genus Luciella differs from the other genera in the Pfiesteriaceae by a least one plate in the plate tabulation and in the configuration of the two anterior intercalary plates. An SSU rDNA phylo- genetic analysis confirmed the genus as monophyletic and distinct from the other genera in the Pfie- steriaceae. The morphology of Luciella masanensis closely resembles Pfiesteria piscicida Steid. et J. M. Burkh. and other Pfiesteria-like dinoflagellates in size and shape, making it easily misidentified using LM. Luciella atlantis, in contrast, has a more distinc- tive morphology. It can be distinguished from L. masanensis and other Pfiesteria-like organisms by a larger cell size, a more conical-shaped epitheca and hypotheca, larger rhombic-shaped intercalary plates, and an asymmetrical hypotheca. The genus Luciella is assigned to the order Peridiniales and the family Pfiesteriaceae based on plate tabulation, plate pat- tern, general morphology, and phylogenetic analysis. Key index words: dinoflagellate; heterotrophic; ITS; morphology; Peridiniales; Pfiesteriaceae; phylogeny; SSU Abbreviations: APC, apical pore complex; bp, base pairs; CCMP, The Provasoli-Guillard National Center for Culture of Marine Phytoplankton; cp, closing plate; DAPI, 4¢ ,6-diamidino-2- phenylindole; f.p., flagellar pore; ITS, internal transcribed spacer; l.f., longitudinal flagellum; 1 Received 12 October 2006. Accepted 12 January 2007. 2 Author for correspondence: e-mail ptrice@vims.edu. J. Phycol. 43, 799–810 (2007) Ó 2007 Phycological Society of America DOI: 10.1111/j.1529-8817.2007.00370.x 799