Halamphora normanii

Observations

Contributor: Joshua Stepanek - February 2011
Length Range: 20-30 µm
Width Range: 4.3-5 µm
Striae in 10 µm: 18-20

Description

Valves are semi-lanceolate with an arched dorsal margin. The ventral margin is straight to slightly convex. Valve apices are protracted, capitate, and ventrally curved. The raphe is located near the valve midline, and is straight to slightly arched with proximal raphe ends deflected sharply toward the dorsal margin. The axial area is narrow on the dorsal side and extends nearly to the valve margin on the ventral side. A fascia is present on the dorsal side, more or less round to elliptical, 'open' on the ventral side and separated from the dorsal margin by a row of short striae. A ventral fascia is absent. A siliceous thickening is present on the dorsal valve side of the central area. Dorsal striae are punctate, and parallel to slightly radiate. Ventral striae are composed of a single row of very short areolae running continuously along the ventral margin. The Ventral striae can be difficult to resolve in the LM if the valve is tilted.