• Category
  • Length Range
    12-26 µm
  • Width Range
    5.3-9.1 µm
  • Striae in 10 µm
  • Synonyms
    Achnanthes biorettii Germain



Valves are elliptical. Both valves have narrow axial areas, which are often oblique to the apical axis and not parallel between the two valves. The central area is transversely elliptical or rectangular, bordered by 4-7 shortened striae of variable length. The raphe is straight or sigmoid near the apices, with slightly expanded terminal ends, but without terminal raphe fissures. The central raphe ends are simple or slightly expanded externally. Internally, the central raphe ends curve toward opposite sides. Striae are radiate through both valves and continue to the valve mantle, 23-27 in 10 µm in the middle and up to 30 in 10 µm at the apices. The external and internal openings of the areolae are circular, becoming transapically elongated toward the margins.

Original Description

Valva elliptica, apicibus largiter rotundatis (18-20 μm longa, 8-10 μm lata); striae omnes radiantes (22-25 in 10 μm) evidenter punctatae, aream longitudinalem angustam limitantes; area centralis secundum quadrilateram dilatata cum striis majoribus et minoribus alternatim; raphe evidenter obliquus secundum axem longitudinalem, pseudoraphe leviter obliquus.

  • Basionym
    Achnanthes bioreti
  • Author
    Germain 1957
  • Length Range
    18-20 µm
  • Width
    8-10 µm
  • Striae in 10µm

Original Images

Orig Illustr 1

Cite This Page

Potapova, M. (2010). Psammothidium bioretii. In Diatoms of North America. Retrieved April 21, 2024, from https://diatoms.org/species/psammothidium_bioretii


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Psammothidium bioretii 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.