Trigonium curvatus sp nov and Trigonium arcticum (Bacillariophyceae) from the surface sediments of Prydz Bay, East Antarctica

Here we propose a new species of genus Trigonium namely Trigonium curvatus from the surface sediments of coastal Antarctica. A comparative study was done between Trigonium curvatus and Trigonium arcticum to find out the differential morphological characters. Trigonium curvatus is differentiated from the earlier described Trigonium arcticum on the basis of valve morphology such as the presence of clustered rimoportulae at centre of the valve, concave sides of the valve, smaller areolae, constricted structure of areolae and fewer pores surrounding areolae. On the contrary, in Trigonium arcticum rimoportulae are absent or inconspicuous, sides of the frustules are convex/straight and it has larger areolae which appear to be flattened with more pores encircling it. Both species show basic resemblance to genus Trigonium such as triangular valve structure, centrally radiating areolae and valve apices comprised of pseudocelli. Hence, it is proposed that Trigonium curvatus is different from the originally described Trigonium arcticum and is a new species of genus Trigonium.