Nitzschia alpinobacillum Lange-Bertalot, 1993

Notes.

The outline of the frustules is lanceolate, distended with capitate to acutely rounded apices (Fig. 3AX-BI). Valves are 15-22 µm length and 3.0-4.0 µm in width. The ratio of length and width is 4.21-6.41. Striae 23-25 in 10 µm visible in LM. Fibulae are visible 10-14 in 10 µm . Striae are uniseriate, arranged transapically. Areolae are covered by the hymenes. Along the edge of the valve, where the raised raphe canal is located, two longitudinal rows of areolae are present - a doublet nearer to the raphe opened to the interior of the raphe canal and a single areola at the junction with the valve face opened to the valve interior. (Fig. 10A, C-D). The distal mantle is narrow. Internally, fibulae have equal spacing; there is no wider gap between the centre fibulae (Fig. 10B). Distal raphe fissures terminate with small helictoglossa (Fig. 10D).