• Category
  • Length Range
    5.5–11 µm
  • Width Range
    3.2-6.0 µm
  • Striae in 10 µm
  • Synonyms
    Achnanthes subatomoides (Hust.) Lange-Bert. and Archibald in Krammer and Lange-Bert.
    Achnanthidium subatomoides (Hust.) Monnier, Lange-Bert. and Ector in Monnier et al.



Valves are elliptical, 3.2-6.0 µm wide and 5.5-11 µm long. On the raphe valve, the axial area widens in the central portion of the valve, forming a "bow-tie" shaped central area. The raphe is straight, without terminal raphe fissures. Externally, the proximal raphe ends are expanded. Internally, the proximal raphe ends curve to opposite sides. On the rapheless valve, the axial area is narrow and linear, with a central expansion forming a rhomboidal or 'bow-tie" shaped central area. Striae are radiate and number 30-40 in 10 µm. Both external and internal openings of the areolae are transapically elongated. One row of areolae is positioned on the valve margin.


Freshwater, oligotraphentic species

Original Description

Kann wegen der wesentlich zarteren Struktur nicht mehr mit Taf. 403, Fig. 51-53 verbunden werden.

  • Basionym
    Navicula subatomoides
  • Author
    Hust. in Schmidt et al. 1936

Original Images

Pssubatomoid  Orig Illustr
Pssubatomoid  Orig Descr
Original text and images reproduced with permission by Koeltz Scientific.

Cite This Page

Potapova, M. (2009). Psammothidium subatomoides. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/psammothidium_subatomoides


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