• Category
  • Length Range
    26-36 µm
  • Width Range
    6.0-7.1 µm
  • Striae in 10 µm



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.


Biremis corcumtexta is usually found in inland waters of high mineral content or in coastal habitats

Original Description

Kiang Wau, Ostasien. Navicula circumtexta Meister, nov. spec. Die mittlere, von den Längslinien eingefaβte Schalenpartie lieft höher als die Randzone.

  • Basionym
    Navicula circumtexta
  • Author
    F.Meister ex Hust. in A.Schmidt et al. 1934

Original Images

 Navicula circumtexta orig illus
Biremis circumtexta orig descr

Cite This Page

Potapova, M. (2011). Biremis circumtexta. In Diatoms of North America. Retrieved April 16, 2024, from https://diatoms.org/species/biremis_circumtexta


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Biremis circumtexta from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.