Tetracyclus
Ralfs 1843 Category: Araphid
TYPE SPECIES: Tetracyclus lacustris Ralfs
CLASS: Fragilariophyceae
ORDER: Tabellariales
FAMILY: Tabellareaceae
- frustules heavily silicified
- transapical costae massive
- striae uniseriate
Frustules of Tetracyclus are heavily silicified. The valves are elliptical to elongate, and often capitate. The valve margins may be expanded centrally. The valve face is flat, while the valve mantle is relatively high. Striae are uniseriate and continue over the costae. Valves may have up to two rimoportulae, positioned near the valve center. Cells form zig-zag colonies joined by mucilage pads.
Tetracyclus is considered a close relative of Tabellaria. Tetracyclus is common in the fossil lacustrine deposits of western North America. In present day sites, it occurs mostly in high latitude and high altitude oliotrophic lakes.
Cite This Page:
Spaulding, S., and Edlund, M. (2008). Tetracyclus. In Diatoms of the United States. Retrieved June 19, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Tetracyclus
Contributor: Sarah Spaulding | Mark Edlund - December 2008
Citations
Williams, D.M. (1985). Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Bibliotheca Diatomologica 8: 1-228.
Williams, D.M. (1987). Observations on the genus Tetracyclus Ralfs (Bacillariophyta) II. Morphology and taxonomy of some fossil species previously classified in Stylobium Ehrenberg. British Phycological Journal 24: 317-327.
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.
Williams, D.M. (1990). Cladistic analysis of some freshwater araphid diatoms (Bacillariophyta) with particular reference to Diatoma and Meridion. Plant Systematics and Evolution 171: 1615-6110.
Williams, D.M. (1990). Distrionella D.M. Williams, nov. gen., a new araphid diatom (Bacillariophyta) genus closely related to Diatoma Bory. Archiv für Protistenkunde 138: 171-177.
Williams, D.M. (1990). Examination of auxospore valves in Tetracyclus from fossil specimens and the establishment of their identity. Diatom Research 5: 198-194.
Williams, D.M. (1994). Fossil species of the diatom genus Tetracyclus (Bacillariophyta, ellipticus species group): Morphology, interrelationships and the relevance of ontogeny. Philosophical Transactions of the Royal Society of London, B, 351:1 759-1782.
Williams, D.M. and Li, J. (1990). Observations on the diatom genus Tetracyclus Ralfs (Bacillariophyta) III. Description of two new species from Chinese fossil deposits. British Phycological Journal 25: 335-338.