• Category
  • Length Range
    25.8-46.6 µm
  • Width Range
    7.6-11.2 µm
  • Striae in 10 µm
    9-12 in the valve center, up to 14 at the apices

Identification

Description

Valves are dorsiventral with rounded ends. The dorsal margin is strongly arched; the ventral margin is weakly concave with a tumid center, becoming nearly flat in smaller specimens. The central area is wider than the axial area and elliptic. The raphe is distinctly lateral, becoming reverse-lateral near the proximal ends and filiform near the terminal ends. Proximal raphe ends are deflected ventrally and terminate in weakly inflated pores. Distal raphe ends are deflected dorsally at a 45 degree angle. Striae are radiate, becoming more strongly radiate near the apices. Striae are distinctly punctate with areolae that number 24-28 in 10 µm. Stigmata are lacking.

Autecology

This taxon is widespread in the western US where its preferred habitats are springs and small lakes and streams. The five larger specimens shown here were collected from a small prairie stream in eastern Montana; the two smallest specimens are from a pothole lake in North Dakota and a small stream in southern California. The pH values of these waters range from 7.81 to 9.00 and specific conductance values range from 1693 to 7700 µS/cm. Unlike C. alpestris, C. hantzschiana is not restricted in distribution to glaciated regions and may also be found in more southerly, unglaciated habitats. Krammer (2002) reports that C. hantzschiana is widespread in temperate regions in oligo- to mesotrophic waters with an average electrolyte content.

Iron  Spring 2
Credit: Loren Bahls
Iron Spring, Carter County, Montana: home of Cymbella hantzschiana

Original Description

  • Basionym
    Cocconema pachycephalum
  • Author
    Rabenh. 1861
  • Length Range
    25-59 µm
  • Width
    8-12 µm
  • Striae in 10µm
    8-11(12) at valve center, 13-15 near the ends

Original Images

Cymbella hantzschiana orig illus
Cymbella hantzschiana orig illus 2
Cocconema pachycephalum orig descr

Cite This Page

Bahls, L. (2016). Cymbella hantzschiana. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/cymbella_hantzschiana

Responses

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