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J Phycol. 2012 Apr;48(2):436-54. doi: 10.1111/j.1529-8817.2012.01132.x. Epub 2012 Mar 19.

CRYPTIC AND PSEUDO-CRYPTIC DIVERSITY IN DIATOMS-WITH DESCRIPTIONS OF PSEUDO-NITZSCHIA HASLEANA SP. NOV. AND P. FRYXELLIANA SP. NOV.(1).

Journal of phycology

Nina Lundholm, Stephen S Bates, Keri A Baugh, Brian D Bill, Laurie B Connell, Claude Léger, Vera L Trainer

Affiliations

  1. The Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, 1307 Copenhagen K, DenmarkFisheries and Oceans Canada, Gulf Fisheries Centre, P.O. Box 5030, Moncton, New Brunswick E1C 9B6, CanadaMarine Biotoxin Program, Environmental Conservation Division, Northwest Fisheries Science Center, NOAA Fisheries, 2725 Montlake Boulevard East, Seattle, Washington 98112, USASchool of Marine Sciences, University of Maine, Orono, Maine 04469, USA.

PMID: 27009733 DOI: 10.1111/j.1529-8817.2012.01132.x

Abstract

A high degree of pseudo-cryptic diversity was reported in the well-studied diatom genus Pseudo-nitzschia. Studies off the coast of Washington State revealed the presence of hitherto undescribed diversity of Pseudo-nitzschia. Forty-one clonal strains, representing six different taxa of the P. pseudodelicatissima complex, were studied morphologically using LM and EM, and genetically using genes from three different cellular compartments: the nucleus (D1-D3 of the LSU of rDNA and internal transcribed spacers [ITSs] of rDNA), the mitochondria (cytochrome c oxidase 1), and the plastids (LSU of RUBISCO). Strains in culture at the same time were used in mating studies to study reproductive isolation of species, and selected strains were examined for the production of the neurotoxin domoic acid (DA). Two new species, P. hasleana sp. nov. and P. fryxelliana sp. nov., are described based on morphological and molecular data. In all phylogenetic analyses, P. hasleana appeared as sister taxa to a clade comprising P. calliantha and P. mannii, whereas the position of P. fryxelliana was more uncertain. In the phylogenies of ITS, P. fryxelliana appeared to be most closely related to P. cf. turgidula. Morphologically, P. hasleana differed from most other species of the complex because of a lower density of fibulae, whereas P. fryxelliana had fewer sectors in the poroids and a higher poroid density than most of the other species. P. hasleana did not produce detectable levels of DA; P. fryxelliana was unfortunately not tested. In P. cuspidata, production of DA in offspring cultures varied from higher than the parent cultures to undetectable.

© 2012 Phycological Society of America.

Keywords: ITS; Pseudo-nitzschia; cox1; cryptic; diatom; domoic acid; rbcL

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