• Category
  • Length Range
    11-16 µm
  • Width Range
    5-7 µm
  • Striae in 10 µm



The valves are heteropolar, 11-16 µm long by 5-7 µm wide. The head-pole is broadly rounded while the foot-pole is capitate. The keel is low and is slightly wider than the mantle face. The apical axial line is visible in the LM while the costae are not. In the SEM the the costae have a density of 55 in 10 µm. Between the costae are 2-3 rows of slit-shaped areolae. The extremely abreviated fibulae, in a density of 8-10 in 10 µm, are visible in the LM and arise from 2-4 costae. The portulae have 2-4 costae entering them. The rows of areolae are interrupted between the fibulae before they enter the portulae.


Original Description

Valve oval, basel end with capitate protuberance; alae small but distinct, 8-10.10 µ; alar canals not well defined; structure very delicate, striae invisible; length 13.0-14.0 µ, width 6.2 µ.

  • Author
    M.H.Hohn and Hellerman 1963
  • Length Range
    13-14 µm
  • Width
    6.2 µm

Original Images

New Sp Card002
Description Edit

Cite This Page

English, J. (2011). Surirella stalagma. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/surirella_stalagma


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