• Category
  • Length Range
    30-54 µm
  • Width Range
    8-10 µm
  • Striae in 10 µm



Valves are linear-lanceolate with margins slightly convex to nearly straight and apices bluntly produced. The axial area is straight, narrow and expanded to form an asymmetric, elliptic to nearly rectangular central area. The raphe is straight and filiform, becoming lateral at about ½ the way between the apex and central area. External proximal raphe ends are enlarged. Striae are distinctly punctate and radiate, except at the apices where they are parallel.

Co-occurs with the nominate variety in alkaline, lentic habitats.


Original Description

  • Basionym
    Mastogloia smithii var. lacustris
  • Author
    Grunow 1878


Jul 15, 2024 - Change in rank

This taxon was reported here as M. smithii var. lacustris Grunow until this date. The publication, Lee et al. 2014, documents that M. smithii var. lacustris Grunow is recognized at the rank of species as M. lacustris (Grunow) Van Heurck and it is now updated, with approval of P. Kociolek. - S. Spaulding

Cite This Page

Kociolek, P. (2011). Mastogloia lacustris. In Diatoms of North America. Retrieved July 15, 2024, from https://diatoms.org/species/mastogloia_smithii_var._lacustris


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