New record of Sargassum zhangii (Sargassaceae, Fucales) in India based on nuclear and mitochondrial DNA barcodes

Abstract

Brown algal genus Sargassum encompasses some of the most invasive seaweeds in the oceans across the world. Here we report the occurrence of Sargassum zhangii in Palk Strait, southeast India. Hundreds of natural populations of this seaweed were observed in the collection site. BLASTn similarity search using nuclear DNA internal transcribed spacer1 (ITS1) and mitochondrial DNA cytochrome oxidase 1 (COX?1) gene of this isolate indicated Sargassum zhangii as the most homologous sequence available in the repository. Pairwise distances among these isolates were very low, 2.8?נ10?3 and 1.3?נ10?2 with ITS1 and COX?1, respectively, which suggests conspecificity and a recent introduction. Phylogenetic analyses along with other members of genus Sargassum conducted using Bayesian Inference resulted in well-resolved phylograms with robust clades comprising two isolates of S.?zhangii, further confirming conspecificity. With this first report of this seaweed outside China, invasive potential of S.?zhangii is highlighted that warrants immediate global attention. As this is the first time that molecular systematics have been used to catalogue species invasion in India, its efficacy, as well as the necessity for further cataloguing of species invasions using this approach, are highlighted. ? 2016 Dipartimento di Biologia, Universit? di Firenze.