• Category
  • Length Range
    14.6-25.7 µm
  • Width Range
    5.1-6.6 µm
  • Striae in 10 µm
  • Synonyms
    Navicula vitrea (Østrup) Hust.
    Navicula festiva Krasske



Valves are lanceolate with rounded, protracted, rostrate ends. Striae are radiate throughout, measuring 26-30 in 10 µm. A large, lanceolate conopeum covers between 1/2 and 3/4 of the valve face. Longitudinal lines exist in the conopeum, near its margins. These lines, as determined by SEM, are valve-long breaks in the canopeum. This structure also has small, transverse striations on either side of the raphe. The axial area is narrow and the raphe is filiform, with relatively separated proximal ends. Distal raphe ends deflect unilaterally. Areolae not visible in LM.


Original Description

F. vitrea m. Fig. 30 660/1. L. 0,02-0,024 mm., B. 0,0055 mm. Valve nearly linear; apices truncate. Central pores comparatively distant. Striae exceedingly delicate, just visible on applying Zeiss' Apochromate 2 mm.; they appear to be at right angles to the raphe. I think I have seen two longitudinal lines close to and parallel with the margin, but I am not quite sure of it. The reason why I have placed this small hyaline form under Frustulia is mostly on account of the appearance of its central nodule. It may perhaps be related to Navicula El Kab O.M. (Bacil. a. d. Natronthalern El Kab tab. XII, fig. 22) which the author places under the Navicula cuspidata group. Here and there. More conspicuous in a gathering labelled: »Covering bare spots on peaty ground«. South side of Trangisvaagfjord (Syderö)1.

  • Basionym
    Frustulia vitrea
  • Author
    Østrup 1901
  • Length Range
    20-24 µm
  • Width
    5.5 µm

Original Images

Fallacia Vitrea Orig Desc Plate And Text

EMAP Assessment

EMAP Distribution

Navicula Festiva  Krasske 40
Map 40

Response Plots

Navicula Festiva  Krasske

Cite This Page

Bishop, I. (2016). Fallacia vitrea. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/fallacia_vitrea


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