(Skvortzow) Metzeltin, Lange-Bertalot and Nergui 2009 Category: Symmetrical biraphid
BASIONYM: Frustulia vulgaris var. asiatica Skvortzow 1928
Contributor: Carrie Graeff - February 2012
Length Range: 43-49 µm
Width Range: 8.0-9.0 µm
Striae in 10 µm: 30-32 in the center valve, 34-35 at the ends
Valves are linear-lanceolate, with very slightly constricted apices. Populations often exhibit a narrow size range. Areolae are round or oval. They form transverse striae that are radiate at the center of the valve and slightly or strongly convergent near the apices. Striae circumradiate the apices. The single row of areolae closest to either side of the raphe forms a continuous line that begins and ends at the poles and curves around the rounded central area. This feature is distinct under the light microscope, especially at the central area. Small, irregularly spaced poroids are present in the central area or near the raphe. The raphe branches and longitudinal ribs are slightly curved. The longitudinal ribs fuse with the helictoglossae to form a porte-crayon. These longitudinal ribs are incomplete at the central nodule. The central nodule is relatively flat. The external proximal and distal raphe ends form a small Y-shape, a feature observable with electron microscopy. The shape of the central area is generally ovoid, and the size of the central area may vary within a population.
These records of Frustulia asiatica are from Hawaii. To date, this species has not been documented from the continental US, however F. asiatica can be compared to populations in California. We have observed California specimens that are similar in morphology to both F. asiatica and F. vulgaris. Further work may be needed to determine if the California specimens are a separate species.
Basionym: Frustulia vulgaris var. asiatica
Author: Skvortzow 1928
Length Range: 53 µm
Width Range: 8.5 µm
Striae in 10 µm: 24
FRUSTULIA VULGARIS Thwaites var. ASIATICA var. nov. Plate 2, fig. 12.
Valve lanceolate, with obtuse rounded ends. Length, 0.0527 millimeter; breadth, 0.0102. Striae, 23 in 0.01 millimeter.
Metzeltin, D., Lange-Bertalot, H. and Soninkhishig, N. (2009). Diatoms in Mongolia. Iconographia Diatomologica (H. Lange-Bertalot, ed.), Vol. 20, A. R. G. Gantner Verlag K. G., Ruggell, 691 pp.
Skvortzow, B.W. (1928). Diatoms of Khingan, North Manchuria, China. Philippine Journal of Science 35:39-51.