New diatom species Navicula davidovichii from Vietnam (Southeast Asia)

We present light and scanning electron microscopical observations on one new species of Navicula Bory sensu stricto from Vietnam. The new species, Navicula davidovichii Chudaev, Glushchenko, Kulikovskiy & Kociolek sp. nov., possesses all typical morphological features for the genus, including uniseriate striae covered by internal convex hymenes, median raphe with accessory rib at the internal surface, and hooked external distal raphe ends. Navicula davidovichii sp. nov., is distinguished from others in the genus on the basis valve outline, shape of the apices, as well as striae and areolar densities. The very interesting shape of the valve, with widely rounded capitate apices, is more typical for species in the genus Pinnularia than in Navicula. Morphologically similar species are almost unknown, except possibly Navicula reinhardtii (Grunow) Grunow. Comparison with the above-mentioned species is given.

Navicula amoyensis sp. nov. (Bacillariophyceae), a new benthic brackish diatom species from the Jiulong River estuary, Southern China

Based on the light and scanning electron microscopy observations, we present a detailed description of a new brackish diatom Navicula amoyensis sp. nov. Samples were collected from an intertidal sand flat in the Jiulong River estuary, Southern China. The key diagnostic features of this species include the simple terminal raphe endings, broad terminal area, two rows of perpendicular apical pores, a wide contracted girdle region with pectinate margin and internal proximal raphe endings with a raised siliceous rib and accessory rib. Furthermore, the main taxonomic features of N. amoyensis sp. nov. and the genera Hippodonta and Navicula are also discussed in detail.