• Category
  • Length Range
    15-33 µm
  • Width Range
    4.5-8.5 µm
  • Striae in 10 µm
    11-14 in the center valve
  • Reported As
    Eunotia praerupta var. bigibba (Krammer and Lange-Bertalot 1991, Taf. 150, Figs 1-7)



Ventral margin is moderately concave to almost straight (smaller valves). Dorsal margin is convex and biundulate in medium-sized to larger valves and weakly biundulate to straight in smaller valves (not shown above). The double undulations on the dorsal margins are often quite variable in height and shape from consistently rounded to more pointed. The apices are obliquely capitate and dorsally reflexed in medium-sized to larger valves and truncate in smaller valves. Helictoglossae positioned somewhat distant from the apices. The distal raphe ends are curve on to the valve face and are clearly visible in the LM. Striae are radiate. One apical rimoportula is present just dorsal to the center of the apex (visible in SEM). Also under SEM, the internal openings of the areolae are aligned in a narrow groove.

Eunotia subherkiniensis has consistently been recorded under incorrect names in North America, primarily as E. bigibba Kützing sensu Grunow. The illustrations of E. bigibba (E. praerupta var. bigibba) in Krammer & Lange-Bertalot (1991, Taf. 150: Figs 1 – 7) are in error and the correct type of E. bigibba is described in Kützing 1849 and a lectotype is designated and illustrated in Lange-Bertalot et al. 2011 (Pl. 83, fig. 1).


Found in streams, wet walls and waterfalls, often epiphytic on bryophytes.

Original Description

Valves with moderately concave to almost straight (smallest specimens) ventral margins. Dorsal margins from strongly to slightly bigibbous, inflations of smallest specimens merge to a single one. Ends more or less protracted obliquely capitate and dorsally reflexed, in smallest specimens only simply truncate. Length 10-30 μm, breadth 5-8 μm. Short terminal raphe fissures usually in somewhat distant position from the poles (as in E. bigibba, but unlike E. papiliofalsa). Striae 12-15/10μm, only little denser spaced at the ends than in the middle of the valves. Areolae not to resolve in LM, SEM ca. 40 / 10 μm (see Figs 95: 10, 11; 96: 1-6).

  • Author
    Lange-Bert. 2011
  • Length Range
    10-30 µm
  • Width
    5-8 µm
  • Striae in 10µm

Original Images

Eunotia subherkiniensis orig illus
Eunotia Subherkiniensis  Orig Descr

Cite This Page

Furey, P. (2012). Eunotia subherkiniensis. In Diatoms of North America. Retrieved April 16, 2024, from https://diatoms.org/species/eunotia_subherkiniensis


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