(Greville) Heiden 1906 Category: Symmetrical biraphid
BASIONYM: Navicula lewisiana Greville 1863
Contributor: Carrie Graeff - March 2010
Length Range: 255.0-265.0 µm
Width Range: 45.0 µm
Striae in 10 µm: 22-24
Valve of Frickea lewisiana are linear-lanceolate with bluntly rounded apices. There is little relative variation in the lengths of specimens, which were 255.0-265.0 µm in length and 45.0 µm in breadth. The majority of the striae are perpendicular, but they become convergent near the apices. Striae are composed of small, round areolae. Striae density is 22-24 in 10 µm. The longitudinal ribs are complete and extend to the helictoglossa. At the central area, the ribs enclose the central nodule but do not fuse with it. Externally, both the proximal and distal raphe ends are T-shaped. The areolae on the valve face opposite the location of the helictoglossa are highly unorganized and sparse. The areolae around the relatively small, symmetrical central area are expanded transversely, several times the length of the typical areolae openings on the valve. Rows of poroids are present between the raphe and longitudinal ribs near the central area and apices.
Basionym: Navicula lewisiana
Author: Greville 1863
Length Range: µm
Striae in 10 µm:
Greville, R.K. (1863). Descriptions of new and rare Diatoms. Series VIII. Transactions of the Microscopical Society, New Series, London 11(3):13-21, pl. I.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Schmidt, A. (-). (1874-1959). Atlas der Diatomaceen-Kunde, von Adolf Schmidt, continued by Martin Schmidt, Friedrich Fricke, Heinrich Heiden, Otto Muller, Friedrich Hustedt. Reprint 1984, Koeltz Scientific Books, Konigstein, 480 plates.