(Braun ex Rabenhorst) Grunow in Van Heurck 1885 Category: Araphid
BASIONYM: Denticula thermalis var. rupestris Kützing 1849
SYNONYM(S): Gomphogramma rupestre (Kützing) Braun in Rabenhorst 1853
Contributor: Ian Bishop - January 2016
Length Range: 8-22 µm
Width Range: 4.7-8.4 µm
Striae in 10 µm: 24-28
Valves are elliptic-lanceolate, with broad, unconstricted apices. The axial area is wide and indistinct. Striae are parallel, with individual erratic striae that intrude into the axial area. Costae are primary and robust, and become inflated and relatively indistinct in axial area; 3-4 in 10 µm. A single rimoportula is present at one valve end. Girdle bands are incomplete. Septae extend approximately 1/4 of the way into the valve, and alternate orientation from one band to the next.
Basionym: Denticula thermalis var. rupestris
Author: Kützing 1849
Length Range: µm
Striae in 10 µm:
Kützing, F.T. (1849). Species Algarum. Lipsiae. F.A. Brockhaus, 922 pp.
Van Heurck, H. (1881). Synopsis des Diatomées de Belgique. Atlas. Ducaju & Cie., Anvers. pls 31-77.
Van Heurck, H. (1885). Synopsis des Diatomées de Belgique. Texte. Martin Brouwers & Co., Anvers. p. 157. (description).
Williams, D.M. (1987). Observations on the genus Tetracyclus Ralfs (Bacillariophyta) I. Valve and girdle structure of the extant species. British Phycological Journal 22: 383-399. 10.1080/00071618700650451
The specimens imaged for this page were collected from Nantahala River near Rainbow Springs, North Carolina. Similar to T. hinziae and T. glans (2/4 of the other extant Tetracyclus species known) populations in the Pacific Northwest, T. rupestris is found to co-occur with specific araphid taxa in the Tabellaria, Meridion, and Diatoma genera.