Psammothidium
Bukhtiyarova & Round 1996 Category: Monoraphid
TYPE SPECIES: Psammothidium marginulatum (Grunow) Bukhtiyarova and Round
Image Credit: Marina Potopova
CLASS: Bacillariophyceae
ORDER: Achnanthales
FAMILY: Achnanthaceae
- Raphe valve convex
- Rapheless valve concave
- Apicies rounded
- Striae similar on both raphe and rapheless valves
Frustules are small, elliptic, lanceolate-elliptic, or linear-elliptic in shape. Frustules are bent in girdle view so that the raphe valve is convex and the rapheless is concave, an arrangement that differs from other achnanthoid genera. The length to width ratio ranges between 1.5 and 3.0. The valve apices are broadly rounded. The arrangement of areolae is similar on the raphe and rapheless valves. Striae are radiate and closely spaced, with nearly 30 striae in 10 µm. A distinct, rectangular central area is present on the raphe valve. The central area is more expanded on the rapheless valve than the raphe valve, at least in several species. The terminal raphe fissures vary in shape and orientation from very short and almost straight, to long and strongly deflected in opposite directions.
Psammothidium contains a number of species (over 40, according to Index Nominum Algarum) including species formerly treated as Achnanthes marginulata Grun. in Cleve & Grun. and Achnanthes levanderi Hust. Species of Psammothidium are very abundant on sand grains.
Cite This Page:
Spaulding, S., and Edlund, M. (2009). Psammothidium. In Diatoms of the United States. Retrieved May 18, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Psammothidium
Contributor: Sarah Spaulding | Mark Edlund - January 2009
Reviewer: Marina Potapova
Citations
Bukhtiyarova, L. and Round, F. E. (1996). Revision of the genus Achnanthes sensu lato. Psammothidium, a new genus based on Achnanthidium marginulatum. Diatom Research 11: 1-30.
Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 pp.
Flower, R.J. and Jones, V.J. (1989). Taxonomic descriptions and occurrences of new Achnanthes taxa in acid lakes in the U.K. Diatom Research 2: 227-239.
Kingston, J.C. (2003). Araphid and Monoraphid Diatoms. In: Freshwater Algae of North America. Ecology and Classification (J.D. Wehr and R.G. Sheath, eds). Elsevier Science pp. 595-636.
Lange-Bertalot, H. and Krammer, K. (1989). Achnanthes eine Monographie der Gattung mit Definition der Gattung Cocconeis and Nachtragen zu den Naviculaceae. Bibliotheca Diatomologica 18, 393 pp. Cramer, Berlin, Stuttgart.
Monnier, O., Lange-Bertalot, H., Hoffmann, L. and Ector, L. (2007). The genera Achnanthidium Kützing and Psammothidium Bukhtiyarova et Round in the family Achnanthidiaceae (Bacillariophyceae): a reappraisal of the differential criteria. Cryptogamie, Algologie 28:1 41-158.
Potapova, M. (2012). New species and combinations in monoraphid diatoms (Family Achnanthidiaceae) from North America. Diatom Research 27(1): 29-42. doi:10.1080/0269249X.2011.644636
Round, F. E. and Bukhtiyarova, L. (1996). Four new genera based on Achnanthes (Achnanthidium) together with a re-definition of Achnanthidium. Diatom Research 11: 345-361.