• Category
  • Length Range
    38-49 µm
  • Width Range
    10.8-11.9 µm
  • Striae in 10 µm
    10-13 at the valve center, 15-16 near the apices
  • Reported As
    Cymbella hybrida (Krammer and Lange-Bertalot 1986, p. 337, plate 145, fig. 2 [not figs 1 or 3])
    Cymbopleura hybrida var. capitata (Krammer 2003, p. 63, figs 87:5-14)
    Cymbopleura hybrida (Diatoms of the US)



Valves are linear-elliptic and slightly dorsiventral, with barely convex dorsal and ventral margins and abruptly constricted subcapitate to capitate apices. The axial area is relatively narrow, 2-3 times wider than the raphe. The central area is large and transversely oval or rectangular. The raphe is lateral, becoming filiform near the proximal ends. Proximal raphe ends have small hooks deflected towards the ventral margin. Distal raphe fissures are deflected dorsally. Striae are parallel at the valve center and radiate towards the apices. Areolae are difficult to resolve in LM and number 28-34 in 10 µm.

This taxon overlaps in size and structure with Cymbopleura hybrida var. capitata and its basionym Cymbella hybrida var. capitata and is indistinguishable from them for all practical purposes. It's affinity with Cymbopleura hybrida is weak and it should be treated as a species in its own right.


Cymbopleura elliptica is uncommon in lakes and ponds of the northern Rocky Mountains, where it prefers cold, oligotrophic, circumneutral waters (pH range: 6.80-7.77) with low to moderate levels of dissolved solids (specific conductance range: 53-250 µS/cm).

Lake  Mc Donald 6  January 2010
Credit: National Park Service webcam
Lake McDonald, Glacier National Park, Montana: home of Cymbopleura elliptica.

Original Description

Valves barely dorsiventral, broadly linear to broadly subelliptical, dorsal and ventral margins straight or barely convex, ends narrowly capitate with broad shoulders. Length 30-44 µm, breadth 8-11.5 µm, maximum length/breadth ratio 4.4. Axial area narrow, linear, almost in the median line of the valve. Central area large, more than 1/2 the valve breadth, rhomboid or something irregular, sometimes asymmetrical. Raphe slightly lateral, narrowing towards the distal and proximal ends. Proximal raphe ends distinctly expanded, the outer raphe fissure somewhat ventrally tipped (Fig. 89: 17a); terminal fissures dorsally deflected. Striae radiate throughout, indistinctly punctate. Striae in the middle portion (dorsal) 10-13/10 µm, up to 18/10 µm towards the ends, puncta 30-32/10 µm.

  • Author
    Krammer 2003
  • Length Range
    30-44 µm
  • Width
    8.0-11.5 µm
  • Striae in 10µm
    10-13 at the valve center, up to 18 at the ends

Original Images

Cymbopleura elliptica orig illus
Cymbopleura elliptica orig illus 2
Cymbopleura elliptica orig descr


May 25, 2024 - Recognition of distinct taxon

Images on this taxon page were previously included under a broad circumscription of Cymbopleura hybrida. As of this date, C. elliptica is presented as a unique biological species distinct from C. hybrida. - S. Spaulding and L. Bahls

Cite This Page

Bahls, L. (2012). Cymbopleura elliptica. In Diatoms of North America. Retrieved May 25, 2024, from https://diatoms.org/species/cymbopleura_hybrida


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