title: Alexandrium diversaporum sp. nov., a new non-saxitoxin producing species: Phylogeny, morphology and sxtA genes.
abstract: Species of the PST producing planktonic marine dinoflagellate genus Alexandrium have been intensively scrutinised, and it is therefore surprising that new taxa can still be found. Here we report a new species, Alexandrium diversaporum nov. sp., isolated from spherical cysts found at two sites in Tasmania, Australia. This species differs in its morphology from all previously reported Alexandrium species, possessing a unique combination of morphological features: the presence of 2 size classes of thecal pores on the cell surface, a medium cell size, the size and shape of the 6″, 1', 2⁗ and Sp plates, the lack of a ventral pore, a lack of anterior and posterior connecting pores, and a lack of chain formation. We determined the relationship of the two strains to other species of Alexandrium based on an alignment of concatenated SSU-ITS1, 5.8S, ITS2 and partial LSU ribosomal RNA sequences, and found A. diversaporum to be a sister group to Alexandrium leei with high support. A. leei shares several morphological features, including the relative size and shapes of the 6″, 1', 2⁗ and Sp plates and the fact that some strains of A. leei have two size classes of thecal pores. We examined A. diversaporum strains for saxitoxin production and found them to be non-toxic. The species lacked sequences for the domain A4 of sxtA, as has been previously found for non-saxitoxin producing species of Alexandrium.
authors.affiliation: Sydney Institute of Marine Science, Chowder Bay Road, Mosman, NSW, Australia; School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: s.murray@unsw.edu.au.
authors.forename: Shauna A
authors.initials: SA
authors.lastname: Murray
authors.affiliation: Senckenberg Research Institute, Senckenberg am Meer, German Center for Marine Biodiversity Research (DZMB), Südstrand 44, D-26382 Wilhelmshaven, Germany.
authors.forename: Mona
authors.initials: M
authors.lastname: Hoppenrath
authors.affiliation: Microbial Evolution Research Group, Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
authors.forename: Russell J S
authors.initials: RJ
authors.lastname: Orr
authors.affiliation: National Centre for Marine Conservation and Resource Sustainability, Australian Maritime College, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bolch
authors.affiliation: Section Ecological Chemistry, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: John
authors.affiliation: Sydney Institute of Marine Science, Chowder Bay Road, Mosman, NSW, Australia.
authors.forename: Rutuja
authors.initials: R
authors.lastname: Diwan
authors.affiliation: Sydney Institute of Marine Science, Chowder Bay Road, Mosman, NSW, Australia.
authors.forename: Rouna
authors.initials: R
authors.lastname: Yauwenas
authors.affiliation: Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand.
authors.forename: Tim
authors.initials: T
authors.lastname: Harwood
authors.affiliation: Tasmanian Herbarium, University of Tasmania, Private Bag 4, Hobart, Tasmania 7001, Australia.
authors.forename: Miguel
authors.initials: M
authors.lastname: de Salas
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Brett
authors.initials: B
authors.lastname: Neilan
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Hallegraeff
keywords: Alexandrium diversaporum; PSP; PST; Phylogenetics; Saxitoxin; Systematics; sxtA