• Category
  • Length Range
    11-31 µm
  • Width Range
    4.8-8.0 µm
  • Striae in 10 µm
    11-19, mostly 16-18
  • Reported As
    Diatoma hiemale (Grimes and Rushforth 1982)



Valves are isopolar, but irregular in valve outline. Larger specimens are linear-lanceolate, while specimens at the lower end of the size range are nearly oval. Apicies are broadly rounded. The central sternum is faint. Transapical costae are prominent, mostly horizontal, and number 4-6 in 10 µm. Transapical striae are irregularly spaced and distinct in LM. Internal valves are present in many specimens. The internal valves possess striae, but lack costae, and may be common in populations. Frustules typically attach to one another by the valve face and form long, ribbon-like colonies. Linking spines are present at the valve/mantle junction and are evident in girdle view.

The name Meridion lineare is considered to be invalid by the California Academy of Sciences names catalogue. The original description lacks a Latin component, or reference to one.


Meridion lineare has been collected from the benthos of several ponds and small lakes in the northern Rocky Mountains. Here pH ranges from 7.34 to 7.57 and specific conductance ranges from 16 to 55 µS/cm. This uncommon species appears to be restricted to standing water habitats in the middle latitudes of North America.

Credit: E. William Schweiger, National Park Service
Belly River Beaver Pond, Glacier National Park, Montana: home of Meridion lineare.

Original Description

Valves bilateral, isopolar with strongly rounded poles, mantle tapers from the centre of the valve down towards the poles. This shape is constant in the populations studied. Apical axis 20-65 µm, transapical axis 5-6 µm. The transapical ribs are very prominent, mainly primary and secondary ribs, irregularly placed, measuring 4 in 10 µm. Striae, virgae distinct, irregular, fairly wide relative to the vimines. Sternum, faint but distinct as a centrally dividing line. A single labiate process is present infrequently, appearing in approximately 10 valves per 50 counted. It has not been established from cleaned colonies whether the labiate process has any fixed functional position within the living colony.

  • Author
    D.M.Williams 1985
  • Length Range
    20-65 µm
  • Width
    5-6 µm
  • Striae in 10µm

Original Images

Merlineare Origimag1
Merlineare Origimag2
Merlineare Origdesc

Cite This Page

Bahls, L. (2012). Meridion lineare. In Diatoms of North America. Retrieved May 30, 2024, from https://diatoms.org/species/meridion_lineare


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