Thalassiosira licea Fryxell
In girdle view, the cells are rectangular with the pervalvar axis shorter than the diameter. Valves (Fig. 1, 2; SEM) are areolate with the areolae arranged eccentrically, or more rarely, in fascicles. There is a single central fultoportula surrounded by several somewhat larger areolae. There is a single marginal ring of fultoportulae, each of which possesses delicate lateral “wings” on the valve exterior. Most cells have 3-6 longer occluded processes intercalated between the marginal fultoportulae; rarely, none. There is a single rimoportula approximately midway between two fultoportulae, 4-5 areolae in from the margin. The rimoportula is indistinguishable from the occluded processes. Valve diameter of cells from the IRL was found to be 20-24µm (16-36µm from literature records) with fultoportulae numbering 2-3 in10µm; the tubular occluded processes are slightly flared at the apices. Areolae number 12-13 in 10µm near the center and 15-17/10µm at the margin, both slightly higher than the type description (Fryxell 1978). It has been found throughout the central IRL, but rarely. Most previous records are from the Gulf of Mexico; its distribution otherwise is poorly known.