• Category
  • Length Range
    21-46 µm
  • Width Range
    11-18 µm
  • Striae in 10 µm
  • Synonyms
    Nitzschia granulata f. granulata Grunow in Cleve and Möller,1879
  • Reported As
    Nitzschia granulata (Witkowski et al. 2000, pg. 383)
    Nitzschia granulata (Krammer and Lange-Bertalot 1988, pg. 45)



Valves are isopolar, with an eccentric raphe, positioned within a canal. Valves are elliptic to elliptic-lanceolate, with rounded to slightly cuneate apices. Fibulae are spaced evenly. Transapical striae are aligned with fibulae. Striae are coarsely punctate and irregularly spaced. The valve face oramentation is variable, with some specimens displaying a longitudinal hyaline area. The valve margin distal to the raphe may possess a small or large marginal ridge (visible with light microscopy). The raphe itself is not visible, but its presence is inferred by the presence of the fibulae. The fibulae never extend across the entire transapical valve.

Mann (1990) transferred Nitzschia granulata Grunow to Tryblionella granulata (Grunow) Mann in Round, Crawford and Mann. The descriptions in these references are similar, and are accepted as the same taxon. Witkowski et al. (2000, p.383) and Krammer at al. (1988, p.45) report this species as Nitzschia granulata Grunow in Cleve and Möller.


This taxon is a cosmopolitan species, commonly found in the coastal littoral zone and particularly abundant in mudflats. It is epipelic, growing on the surface of sediments in estuaries and coastal marshes.

Original Description

  • Basionym
    Nitzschia granulata f. granulata
  • Author
    Grunow in Cleve & Möller 1879

Cite This Page

Smith, K., Ropp, A., Atchia, I. (2020). Tryblionella granulata. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/tryblionella_granulata


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