Diatoms of North AmericaDiatoms of North America

Pinnularia grunowii

Krammer 2000

Pinnularia grunowii guide
  • Category
    Symmetric Biraphid
  • Length Range
    38.2-46.4 µm
  • Width Range
    8.1-9.3 µm
  • Striae in 10 µm
    11-12

Identification

Pinnularia grunowii LM7 Pinnularia grunowii LM6 Pinnularia grunowii LM4 Pinnularia grunowii LM5 Pinnularia grunowii LM1 Pinnularia grunowii LM2 Pinnularia grunowii LM3
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Description

Valves are linear and triundulate. The central inflation is more narrow, or equal in width, to the distal inflations. The apices are subrostrate to subcapitate and broadly rounded. The raphe is straight, with proximal ends deflected to one side. The terminal raphe fissures are question-mark in shape. The xxial area is narrow and straight. The central area is usually an asymmetric bowtie-shaped fascia. In some specimens, however, the fascia is absent and the central area is rhombic to elliptic. Striae are radiate in the center and convergent at the apices.

Autecology

Specimens shown on this page are from a small tundra pool near Point Barrow, Alaska (Patrick and Freese 1961).

According to Krammer (2000), this taxon is cosmopolitan in distribution and common in the holarctic. It is found in low conductivity waters with pH of 8 or above. It is both epilithic and epiphytic.

Original Description

Synonyms: Pinnularia interrupta sensu Hustedt 1930, fig. 573b; Pinnularia mesolepta (Ehrenberg) W. Smith, morphotype 2 sensu Krammer 1992, p. 119, figs 44: 1-8, 10-12.

Type locality: Reichenbach, Frankenwald, Bavaria, sample Schimanski 137, slide 45 IOK.

Valves linear, margins moderately triundulate, the central inflation equal the breadth or narrower than the other two, ends capitate, somewhat attenuated but broad and obtusely rounded, sharply offset from the valve body; length 27-55 µm, breadth 6.5-9 µm, length-to-breadth ratio 3.7-5.4. Raphe branches commonly straight, filiform, proximal ends deflected laterally, central pores very small, terminal fissures ?-shaped. Axial area narrow, linear, from the rhombic central area clearly differentiated, combined with a small or moderately broad fascia. Striae radiate in the middle becoming strongly convergent towards the ends, 11-14/10 µm.

Well distinguished by size from P. biceps, by the outline from P. angusta and P. pluvianiformis and by the arrangement of the striae. As to P. mesolepta see the discussion under this name.

  • Author
    Krammer 2000
  • Length Range
    27-55 µm
  • Width
    6.5-9 µm
  • Striae in 10µm
    11-14

Original Images

Pinnularia grunowii orig illus
Pinnularia grunowii orig illus 2
Pinnularia grunowii orig illus 3
Pinnularia grunowii orig desc

Citations & Links

Citations

Links

Cite This Page

Leppik, S., Potapova, M. (2025). Pinnularia grunowii. In Diatoms of North America. Retrieved May 17, 2025, from https://diatoms.org/species/339942/pinnularia-grunowii

Responses

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