Abstract:

Nanoneis was identified as a newly recorded diatom genus for China under transmission electron microscope (TEM) in the water samples from the East China Sea and Huanghai Sea (Yellow Sea). The valves of this diatom are bilaterally symmetrical and have a raphe extending through the middle of the valve from one pole to near the center. The raphe of the opposite valve on the same cell extends from the other pole to near the center. The alveoli or ribs of the valve face continue around the valve mantle. Two species were described in this paper, including Nanoneis longta sp. nov. as a new species and Nanoneis hasleae as a new recorded species for China. They have some distinctly different characteristics in the shape of valve surface, the ratio of length to width and the density of alveoli or ribs on valve face. Detailed description of the taxonomic characteristics with TEM photographs of these two species and their ecological distributions were given in this paper. N. longta sp. nov.: cells are narrowly linear in valve view and bilaterally symmetrical with convexity being present in the apices and in the middle of the valve. Cell length 10­12 µm, width 1.0­1.5 µm. The ratio of length to width is about 10:1. Valve structure consisting of thickened ribs perpendicular to the apical axis alternating with thin areas, alveoli, in the greater length of the valve. Ribs and alveoli radically arranged in apical parts of valves. The density of the transapical ribs is approximately 60 in 10 µm. A simple raphe located in the middle of valve, extending from one pole to a point near to the median part of the valve. The opposite valve on the same cell with the raphe extended from the opposite pole to near the center. The specimens were collected from a 20-m layer at latitude 29º 6'' 31'''' N, longitude 126º 57'' 72'''' E, in Nov., 2000.

Key words: East China Sea, Huanghai Sea, nanodiatom, Nanoneis , Nanoneis longta sp. nov