• Category
  • Length Range
    46-50 µm
  • Width Range
    8-9 µm
  • Striae in 10 µm



Valves are linear-lanceolate. Axial area is narrow. Central area is strongly asymmetric, wedge-shaped and bordered by irregularly shortened striae at the primary side and semi-lunate in shape on the secondary side. Raphe is almost straight, but slightly shifted toward primary side near the central valve. Proximal raphe ends are slightly expanded and sharply deflected towards the primary side. Terminal raphe fissures are deflected toward the primary side and bifurcate at the valve apices. Striae are radiate in the central part of the valve and parallel near apices. Striae are 9-10 in 10 µm. Areolae are lineolate and number approximately 24-26 in 10 µm.


This taxon was described from Geronimo Creek, Guadalupe County, Texas. The species was found growing in water of high conductance (926 µS/cm), low total phosphorus (below the detection limit of 33 µg/L), and very high nitrogen concentrations (NO2 + NO3 as N of 12 mg/L).

It was also reported from the USGS southeast regional survey (Bishop et al. 2017).

Original Description

Valves linear-lanceolate, 46-50 µm long, 8-9 µm wide. Raphe almost straight, but near the center slightly bent towards primary side of the valve. Central raphe endings slightly expanded and sharply bent towards primary side. Terminal fissures deflected towards primary side and bifurcate over valve apices. Striae radiate at the middle part of the valve, but parallel near apices, 9-10 in 10 µm. Areolae apically elongate, about 24-26 in 10 µm. Axial area narrow. Central area asymmetrical, bordered by irregularly shortened striae at the primary side, and semi-lunate at the secondary side.

  • Author
    Potapova in Potapova and Charles 2004
  • Length Range
    46-50 µm
  • Width
    8-9 µm
  • Striae in 10µm

Original Images

Nageronim  Or Ill
Nageronim  Or Descr

Cite This Page

Potapova, M. (2011). Navicula geronimensis. In Diatoms of North America. Retrieved April 14, 2024, from https://diatoms.org/species/navicula_geronimensis


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