title: A non-toxigenic but morphologically and phylogenetically distinct new species of Pseudo-nitzschia, P. sabit sp. nov. (Bacillariophyceae).
abstract: A new species of Pseudo-nitzschia (Bacillariophyceae) is described from plankton samples collected from Port Dickson (Malacca Strait, Malaysia) and Manzanillo Bay (Colima, Mexico). The species possesses a distinctive falcate cell valve, from which they form sickle-like colonies in both environmental samples and cultured strains. Detailed observation of frustules under TEM revealed ultrastructure that closely resembles P. decipiens, yet the new species differs by the valve shape and greater ranges of striae and poroid densities. The species is readily distinguished from the curve-shaped P. subcurvata by the presence of a central interspace. The morphological distinction is further supported by phylogenetic discrimination. We sequenced and analyzed the nuclear ribosomal RNA genes in the LSU and the second internal transcribed spacer, including its secondary structure, to infer the phylogenetic relationship of the new species with its closest relatives. The results revealed a distinct lineage of the new species, forming a sister cluster with its related species, P. decipiens and P. galaxiae, but not with P. subcurvata. We examined the domoic acid (DA) production of five cultured strains from Malaysia by Liquid chromatography-mass spectrometry (LC-MS), but they showed no detectable DA. Here, we present the taxonomic description of the vegetative cells, document the sexual reproduction, and detail the molecular phylogenetics of Pseudo-nitzschia sabit sp. nov.
authors.affiliation: Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, 94300, Malaysia.
authors.forename: Sing Tung
authors.initials: ST
authors.lastname: Teng
authors.affiliation: Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, Kelantan, 16310, Malaysia.
authors.forename: Po Teen
authors.initials: PT
authors.lastname: Lim
authors.affiliation: Tunku Abdul Rahman University College, Johor Branch Campus, 85000 Segamat, Johor.
authors.forename: Hong Chang
authors.initials: HC
authors.lastname: Lim
authors.affiliation: Facultad de Ciencias Químicas, Universidad de Colima Km9 Carretera Colima-Coquimatlán, Coquimatlán, Colima, C.P. 28400.
authors.forename: María
authors.initials: M
authors.lastname: Rivera-Vilarelle
authors.affiliation: Centro Universitario de Investigaciones Oceanológicas, Universidad de Colima, Carretera Manzanillo-Barra de Navidad Km 19.5, Colonia El Naranjo, C.P 28860, Manzanillo, Colima, Mexico.
authors.forename: Sonia
authors.initials: S
authors.lastname: Quijano-Scheggia
authors.affiliation: The University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo, 113-8657, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Takata
authors.affiliation: Measurement Science and Standards, Biotoxin Metrology, National Research Council of Canada, 1411 Oxford Street, Halifax, Nova Scotia, Canada, B3H 3Z1.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Quilliam
authors.affiliation: Department of Bioinformatics, Biocenter, University of Wuerzburg, Wuerzburg, D-97074, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wolf
authors.affiliation: Fisheries and Oceans Canada, Gulf Fisheries Centre, P.O. Box 5030, Moncton, New Brunswick, Canada, E1C 9B6.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Bates
authors.affiliation: Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, Kelantan, 16310, Malaysia.
authors.forename: Chui Pin
authors.initials: CP
authors.lastname: Leaw
keywords: ITS2; Malaysia; Mexico; Pseudo-nitzschia sabit; domoic acid; ribosomal RNA genes; secondary structure; sexual reproduction