• Category
  • Length Range
    94-168 µm
  • Width Range
    22-29 µm
  • Striae in 10 µm



Valves are lanceolate with weakly protracted (subrostrate) and broadly rounded apices. The axial area is narrow and widens gradually into the central area, which is longitudinally elongate with convex sides. The raphe is weakly lateral with proximal ends that are moderately distant, somewhat inflated and hooked to the same side. Striae are weakly radiate but convergent very near the apices. Areolae are easily distinguished in LM and number 23-24 in 10 µm. Craticula are present in some specimens.


Craticula acidoclinata is uncommon in small ponds and pools in the Northern Rockies. The Montana population pictured here was found in a small pond in a conifer forest at 2,000 m elevation along the Continental Divide near Helena. The pH of this pond measured 6.98 and specific conductance measured 46 µS/cm. These low pH and specific conductance values distinguish this species ecologically from Craticula cuspidata, which prefers more alkaline water with higher electrolyte content. Craticula acidoclinata was described from an oligo-dystrophic lake in Finland with a pH of 6.5 and a specific conductance of 17 µS/cm.

Original Description

  • Author
    Lange-Bert. and Metzeltin 1996
  • Length Range
    60-110 µm
  • Width
    16-23 µm
  • Striae in 10µm

Original Images

Craticula acidoclinata orig illus
Craticula acidoclinata orig descr

Cite This Page

Bahls, L. (2012). Craticula acidoclinata. In Diatoms of North America. Retrieved June 20, 2018, from https://diatoms.org/species/craticula_acidoclinata


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