Thalassiosira sundarbana sp. nov. (Bacillariophyta), an estuarine diatom from Sundarbans mangrove ecoregion based on morphology and molecular phylogeny

Abstract

SummaryA new species of diatom, Thalassiosira sundarbana, is described based on light and scanning electron microscopy along with molecular phylogeny. The specimen was collected from Chemaguri creek of the Indian part of Sundarbans mangroves, and subsequently a clonal culture was established. Thalassiosira sundarbana possess variable numbers of occluded processes, and one labiate process on the valve face. Valve margin is ribbed and areolae are fasciculated on the valve face. Two rings of strutted processes are present on valve face. Strutted processes are also scattered on the valve face apart from the presence of two rings. Valvocopula and copula have rows of pore, and pleurae are hyaline. Bayesian analyses of nuclear encoded small subunit (SSU) rDNA and plastid encoded rbcL gene confirmed that T. sundarbana is phylogenetically novel. Salinity tolerance experiment with the clonal culture of T. sundarbana showed that this isolate can grow in salinity ranging from 10–35 psu. The maximum growth rate was observed in 15 psu salinity (0.5 divisions 24 h−1). On the basis of morphological features and molecular phylogeny, this clonal isolate is considered as a new estuarine species of Thalassiosira.