Biremis circumtexta
(Meister ex Hustedt) Lange-Bertalot & Witkowski in Witkowski, Lange-Bertalot & Metzeltin 2000 Category: Symmetrical biraphid
BASIONYM: Navicula circumtexta Meister ex Hustedt in A. Schmidt et al. 1934
LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Marina Potapova - October 2011
Length Range: 26-36 µm
Width Range: 6.0-7.1 µm
Striae in 10 µm: 16-18
Description
Valves are lanceolate with slightly protracted apices. Raphe is straight with proximal ends slightly expanded and deflected to the primary side. Striae are marginal, forming a wide, lanceolate axial area. Each marginal stria consists of four areolae, which are easily observed under LM. There is also a longitudinal row of areolae adjacent to the raphe slits on the primary side of the valve. Externally, a thin conopeum extends from the valve margin and covers the areolae, except those those areolae adjacent to the axial area. The conopeum can be observed only under SEM, but under LM, its margin is visible as a longitudinal line crossing the striae. The striae are slightly radiate in the valve center, becoming parallel near the apices.
Original Description
Basionym: Navicula circumtexta
Author: Meister ex Hustedt in A. Schmidt et al. 1934
Length Range: µm
Striae in 10 µm:
Original Description
Kiang Wau, Ostasien. Navicula circumtexta Meister, nov. spec. Die mittlere, von den Längslinien eingefaβte Schalenpartie lieft höher als die Randzone.
Original Images
Cite This Page:
Potapova, M. (2011). Biremis circumtexta . In Diatoms of the United States. Retrieved May 24, 2013, from http://westerndiatoms.colorado.edu/taxa/species/biremis_circumtexta
Species: Biremis circumtexta
Contributor: Marina Potapova
Reviewer: Sarah Spaulding
Image Credit: Marina Potapova
- Valves lanceolate
- Axial area wide, lanceolate
- Striae marginal
- Areolae visible under LM
- On one side of valve, a row of areolae next to raphe
Valves are lanceolate with slightly protracted apices. The axial area is wide and lanceolate. Areolae within striae are easily observed under LM. A longitudinal row of areolae is adjacent to the raphe slits on the primary valve side. A conopeum is visible as a longitudinal line crossing the striae.
Compare
Biremis circumtexta is easily distinguished from other lanceolate naviculoid diatoms by its wide axial area and a single longitudinal row of areolae adjacent to raphe on one side of the valve.
Citations
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Schmidt, A. (-). (1874-1959). Atlas der Diatomaceen-Kunde, von Adolf Schmidt, continued by Martin Schmidt, Friedrich Fricke, Heinrich Heiden, Otto Muller, Friedrich Hustedt. Reprint 1984, Koeltz Scientific Books, Konigstein, 480 plates.
Witkowski, A., Lange-Bertalot, H. and Metzeltin, D. (2000). Diatom Flora of Marine Coasts I. Iconographia Diatomologica 7: 1-925.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 206001
Autecology Discussion
Biremis corcumtexta is usually found in inland waters of high mineral content or in coastal habitats