References:
Patrick, R. & Reimer, C. W. (1975). The Diatoms of the United States 2(1). Monographs of the Academy of Natural Sciences of Philadelphia. Pennsylvania. pp. 29-30; 84-85 [pl.4:6]
Description:
Valve is moderately to strongly dorsi-ventral, usually with a slight bulge (barely tumid) in the central valve margin; extremities are tapered, bluntly rounded; axial area is linear; central area is not well-defined, and is a space that is either lacking or slightly broader; raphe is laterally broad, becoming filiform or slightly reverse-lateral near the blunt, slightly ventrally deflected proximal ends, and dorsally curved on the distal ends (where it reaches the dorsal margin); finely lineate striae are radiate throughout, more widely spaced on the dorsal than the ventral margin, about equal in number near the extremities; length is 20-35µm, breadth is 6-10µm; striae count is about 12 in 10µm becoming 17-28 in 10µm at the extremities (dorsal) and 13-16 in 10µm becoming 17-18 in 10µm at the extremities (ventral) [Hustedt (1930) gives 12-15 dorsal striae in 10µm becoming 20 in 10µm near the extremities); Krammer & Lange-Bertalot (1997) give length and breadth values for this taxon as 17-54µm and 14-18µm, respectively; striae count is 10-11 in 10µm becoming 16-17 in 10µm at the ends; 15-16 dorsal punctae in the centre, 22 in 10µm at the ends
