(Agardh) Agardh 1830 Category: Asymmetrical biraphid
BASIONYM: Frustulia lanceolata C.A. Agardh 1827
Contributor: Loren Bahls - June 2016
Length Range: 121-232 µm
Width Range: 21.8-29.9 µm
Striae in 10 µm: 10-12 at the valve center, up to 14 near the apices
Valves are long and slender, dorsiventral and lanceolate with rounded apices. Length-to-width ratio ranges from 4.9 in smaller specimens to 7.8 in the largest specimens. The dorsal margin is moderately arched. The ventral margin is slightly concave with a gibbous center. The axial area is narrow and linear, slightly wider than the raphe. The central area is small and ovoid. The raphe is lateral, becoming filiform near the proximal and distal ends. Externally, the proximal raphe ends are strongly recurved toward the ventral side. Terminal raphe fissures are deflected dorsally at an angle of almost 90 degrees. Striae are radiate throughout, becoming more strongly radiate near the apices. Areolae number 10-14 in 10 µm. Some elongate, stigma-like areolae appear at the proximal ends of the median ventral striae, but otherwise stigmata are absent.
Note on the type: The original description of Frustulia lanceolata (Agardh 1827) did not include illustrations. Krammer (2002, p. 125) examined the type material from Carlsbad (Bohemia) and did not find any cymbelloid diatoms. Krammer designated a neotype from Westphalia, Germany. Images of the neotype specimens (Krammer 2002, plate 144, figs 1-5) are given below.
Basionym: Frustulia lanceolata
Author: C.A. Agardh 1827
Length Range: µm
Striae in 10 µm:
Agardh, C.A. (1827). Aufzählung einiger in den ostereichischen Ländern gefundenen neuen Gattungen und Arten von Algen nebst ihrer Diagnostik und beigefugten Bemerkungen. Flora oder Botanische Zeitung, Regensburg 2:625-640.
Agardh, C.A. (1830). Conspectus Criticus Diatomacearum. Part 1. Lundae. Litteris Berlingianis. pp. 1-16.
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Cymbella lanceolata is widespread in the Northern Rocky Mountains and Northwestern Great Plains, in lakes and streams where pH ranges from 7.50 to 8.54 and specific conductance ranges from 92 to 1227 µS/cm. This taxon is reported as an alkaliphil, widespread in the United States, and most common in littoral habitats associated with submerged aquatic plants and sometimes with partially decaying vegetation (Patrick and Reimer 1975).
Poplar River on the Northwestern Great Plains in Montana: home of Cymbella lanceolata
Credit/Source: Loren Bahls