Diatoms of North AmericaDiatoms of North America

Navicula libonensis

Schoeman 1969

Navicula Libonensis Guide
  • Category
    Symmetric Biraphid
  • Length Range
    27-35 µm
  • Width Range
    5.9-7.0 µm
  • Striae in 10 µm
    12-13

Identification

Gs138229 Nalib3 Navicula libonensis LM3 Gs138229 Nalib1 Gs138229 Nalib2 Navicula libonensis LM2 Navicula libonensis LM1
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Navicula libonensis SEM1 Navicula libonensis SEM2

Description

Valves are lanceolate with rounded or very slightly drawn-out ends. The axial area is narrow and linear. The central area is transversely elliptical or irregular-rectangular, often slightly asymmetrical. The proximal raphe ends are straight, slightly expanded. Terminal raphe fissures are hooked towards the secondary side. The lineolate striae are radiate, becoming convergent at the valve apices, 12-13 in 10 µm. The areolae are easily observed under LM, 28-32 in 10 µm.

Note that this concept of Navicula libonenesis follows Lange-Bertalot (2001), but the type material of this species have not been photographed. Therefore it is not clear at present whether North American, European, and South African populations represent the same species.

Autecology

In the EPA Western EMAP survey, this taxon was found in low gradient rivers, particularly in the Northern Great Plains. It was found in waters of high pH (often above 8), conductance, alkalinity, and phosphorus. It favored rivers with embedded substrates and was tolerant of turbid waters and human disturbance.

Original Description

The valves are lanceolate with regularly rounded ends which are not produced, 24-32 μ long and 5-7 μ wide. The raphe is straight and filiform bending sharply near the poles towards the same side of the valvar margin; the terminal fissures were observed in only a few cases and appeared to run alongside the valvar margin, thus bending towards the valvar poles; the central poles are small but definite, fairly close together, The axial area is narrow and linear with definite polar areas, and widens into a central area due to the regular or irregular shortening of the central striae. The transapical striae are radial becoming parallel or convergent near the poles, 11-14 in 10 μ (13-14 in 10 μ near the poles of the valve), clearly lineolate. Lineolae form longitudinal striae, 28-30 in 10 μ.

  • Author
    Schoeman 1970
  • Length Range
    24-32 µm
  • Width
    5-7 µm
  • Striae in 10µm
    11-14

Original Images

Nalibonens Or Ill1
Nalibonens Or Il2
Nalibonens Or Descr

Cite This Page

Potapova, M. (2011). Navicula libonensis. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/navicula_libonensis

Responses

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