Phylogeny of araphid diatoms, inferred from morphological and molecular data

The aim of this study was to obtain more complete picture of the phylogeny of 'araphid' diatoms, which was well-grouped in morphology but paraphyletic in previous molecular phylogenetic studies. For phylogenetic reconstructions, SSU rDNA, LSU rDNA, rbcL and psbA were used as phylogenetic markers. Four new genera Plagiostriata, Psammogramma, Psammoneis and Pseudostriatella, were described in this study. The observation of the auxospores on four araphid diatoms, Gephyria, Grammatophora, Pseudostriatella and Tabularia, revealed that the possession of centric-like feature of perizonium in Pseudostriatella was corresponded to its phylogenetic position in the basal araphid clade. The paraphyly of araphid diatoms was strongly supported by the molecular phylogeny as well as the heterogeneity of their auxospore structures. Therefore, more natural classification system should be established after further analyses with larger dataset.