Pseudo-nitzschia simulans sp. nov. (Bacillariophyceae), the first domoic acid producer from Chinese waters

Abstract

A B S T R A C TThe genus Pseudo-nitzschia has attracted attention because of production of the toxin, domoic acid (DA), causing Amnesic Shellfish Poisoning (ASP). Pseudo-nitzschia blooms occur frequently in Chinese coastal waters, and DA has been detected in several marine organisms, but so far no Pseudo-nitzschia strains from Chinese waters have been shown to produce DA. In this study, monoclonal Pseudo-nitzschia strains were established from Chinese coastal waters and examined using light microscopy, electron microscopy and molecular markers. Five strains, sharing distinct morphological and molecular features differentiating them from other Pseudo-nitzschia species, represent a new species, Pseudo-nitzschia simulans sp. nov. Morphologically, the taxon belongs to the P. pseudodelicatissima group, cells possessing a central nodule and each stria comprising one row of poroids. The new species is characterized by the poroid structure, which typically comprises two sectors, each sector located near opposite margins of the poroid. The production of DA was examined by liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses of cells in stationary growth phase. Domoic acid was detected in one of the five strains, with concentrations around 1.05-1.54 fg cell À1. This is the first toxigenic diatom species reported from Chinese waters.

Phylogeny and species delineation in the marine diatomPseudo‐nitzschia(Bacillariophyta) usingcox1,LSU, andITS2rRNAgenes: A perspective in character evolution

“…, , Li et al. ). Mating studies to bolster the biological species concept have also bridged the gap between morphological and molecular approaches to make it more complete (e.g., Amato et al.…”

“…, Li et al. ). In the older literature, the identity of Pseudo‐nitzschia species was based on morphological evidence; later, species identity was further supported by molecular data (Lundholm et al.…”

“…, , Li et al. ). The resolution of using LSU for Pseudo‐nitzschia phylogeny is limited and alignment of the diverse ITS1‐5.8S‐ITS2 sequences is rather difficult (Lim et al.…”

“…The traditional identification of Pseudo-nitzschia species was based solely on the use of morphological characters. With the discovery of several new species, it became necessary to describe and compare additional detailed ultrastructural characters (e.g., types of poroids and details of cingular bands; Lundholm et al 2003, Quijano-Scheggia et al 2009, Lim et al 2012a, Orive et al 2013, Teng et al 2014, 2015, Li et al 2017.…”

Pseudo‐nitzschia nanaoensis sp. nov. (Bacillariophyceae) from the Chinese coast of the South China Sea

“…The recent discovery of two new species, P. simulans (Li et al. ) and P. nanaoensis , from Chinese tropical regions also supports the hypothesis of high species richness in Pseudo‐nitzschia in the tropical zone (Teng et al. ).…”