• Category
  • Length Range
    36.1-64.3 µm
  • Width Range
    7.9-11.9 µm
  • Striae in 10 µm
    11-15 at the valve center, 16-19 near the apices on the dorsal side
  • Synonyms
    Cymbella aequalis var. florentina (Grunow) Cleve 1894
    Cymbella florentina (Grunow) Mills 1934
  • Reported As
    Cymbella subaequalis (Lange-Bertalot and Metzeltin 1996, figs. 94: 24, 25)



Valves are lanceolate and moderately dorsiventral. The dorsal margin is arched and the ventral margin is less strongly arched with a gibbous middle. Apices are rounded and not protracted. The axial area widens gradually from the apices towards the central area, together forming a narrow lanceolate space. The central area is formed by a shallow depression on the dorsal side. The raphe is lateral. Proximal raphe ends are filiform, deflected towards the ventral margin, and tipped with slightly expanded pores. Distal raphe ends are hooked towards the dorsal side. Striae are radiate throughout, more strongly radiate near the apices. Areolae in the striae number 22-24 in 10 µm at the valve center, and are closer together towards the apices where they approach 30 in 10 µm.


Cymbopleura florentina has been recorded from several lakes, ponds, and fens in the northern Rocky Mountains and northwestern Great Plains of Montana. Here pH ranges from 7.3 to 9.5 and specific conductance ranges from 140 to 1500 µS/cm. Krammer (2003) reports C. florentina from "oligotrophic lakes in the Alps and from the Balkans with a moderate electrolyte content", also from "Finnish Lapland and from smaller waters in the plains".

Big  Therriault  Lake
Credit: Loren Bahls
Big Therriault Lake, Ten Lakes Scenic Area, Kootenai National Forest, Montana: home of Cymbopleura florentina.

Original Description

  • Basionym
    Cymbella subaequalis var. florentina
  • Author
    Grunow in Van Heurck 1880

Original Images

Cymbopleura florentina orig illus

Cite This Page

Bahls, L. (2014). Cymbopleura florentina. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/cymbopleura_florentina


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