• Category
  • Length Range
    32-41 µm
  • Width Range
    8.0-9.1 µm
  • Striae in 10 µm
  • Synonyms
    Navicula viridula var. rostellata (Kütz.) Cleve



Valves are linear to linear-lanceolate with slightly convex (more typically) to straight margins and subrostrate apices. The axial area is narrow and straight. The central area is elliptic and slightly asymmetric. The raphe is straight, with external proximal raphe ends that are slightly dilated and bent toward the primary side of the valve. The central nodule is asymmetrically expanded on the internal valve surface to the primary side. Terminal raphe fissures are hooked to the secondary valve side. Striae are bent and radiate around the center. The striae are more distant from one another near the center of the valve, 12-14 in 10 µm. The striae become parallel, then convergent at the apices. The areolae are usually visible under LM and number around 30 in 10 μm.

Note that the original material of Navicula rostellata has not been investigated. As Patrick (Patrick and Reimer 1966) pointed out, the identity of this taxon is not clear as the original illustration shows a linear valve outline and long, narrow apices. Patrick and Reimer (1966) illustrated a specimen from Bengal with linear valve outline and low stria density (9-10 striae in 10 µm) as N. viridula var. rostellata. The concept we present in this page follows Lange-Bertalot (2001).


This taxon tends to be common in low gradient rivers, where it is tolerant of riparian disturbance, embedded stream benthos, turbid waters, and human disturbance.

Original Description

N. minuta, striata, oblonga, lateribus parallelis, apicibus rostratis elongates acutis. Long. 1/90-1/60’’’.

  • Author
    Kütz. 1844
  • Length Range
    25-38 µm

Original Images

Narost  Or Ill
Na Rost  Or Descr

Cite This Page

Potapova, M., Kociolek, P. (2011). Navicula rostellata. In Diatoms of North America. Retrieved June 20, 2024, from https://diatoms.org/species/navicula_rostellata


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