• Category
  • Length Range
    7.9-10.9 µm
  • Width Range
    3.7-4.3 µm
  • Striae in 10 µm



Valves are elliptic to linear-elliptic. The raphe is straight and filiform. The proximal raphe ends are slightly expanded and straight, or nearly so. The distal raphe ends are deflected to the same side. The axial area is very narrow and lanceolate. The central area is variable in size and shape. The areolae are coarse and distinct, forming radiate striae. A row of areolae is positioned next to the axial area. The remaining areolae are separated by a longitudinal hyaline line. The striae are composed of interrupted areolae.

A similar taxon was recognized earlier by Hustedt, but Navicula farta Hustedt in Schmidt et al. 1934 (Pl. 397, Fig. 7-9) considered to be invalid.

Navicula farta has been reported in a number of surveys in the United States. These reports should be reexamined as an incorrect application of a name, and potential alignment with Eolimna metafarta.


This taxon was found in the Southeast Regional Survey (Bishop et al. 2017) in samples from Virginia. It is reported rarely in North America.

Original Description

Eolimna metafarta Kulikovskiy & Lange-Bertalot. sp. nov. (Figs 1-54, 59-68)

Synonym:? Navicula farta Hustedt in Schmidt et al. (1934; figs 397:7-9), nom. inval. Hustedt 1966: 644, fig. 1646) nom. inval. (but see Simonsen 1987: 166-167)

GENERAL DESCRIPTION: LM observations (Figs 1-54), valves elliptical to linear-elliptical; ends broadly rounded. Length 8-33 µm, breadth 4.5-10.5 µm. Raphe filiform, straight or slightly curved with inconspicuous, barely deflected central ends and bent terminal fissures. Axial area variable in width, narrow and almost linear in smaller cell cycle stages but wider and more or less lanceolate in later stages. Central area variable in size, shape and symmetry; some specimens unilaterally extend almost to valve margin. Lateral area developed in larger and medium-sized specimens. Transapical striae radiate throughout, moderately so in proximal parts, becoming on either side more accentuated than others from which they are separated by the more more or less distinct lateral area. The remaining areolae are - somewhat irregularly - more densely spaced, ca. 15 in 10 µm.

SEM observations, external valve view (Figs 59-64), the raphe lies in an elevated sternum flanked by depressions that comprise the adaxial series of areola foramina. The raphe slit is not expanded, or only weakly expanded toward the proximal ends; terminal fissures both bent unilaterally, but to the opposite side of the slightly deflected proximal parts or the raphe. The relief-like appearance of the entire valve face concerns likewise the lateral area being elevated between adaxial depressions and the marginal parts of the valve. Sternum and lateral areae are composed of approximately circular uniseriate formina lying in depressions between elevated virgae. Isolated areolae are generally absent on the mantle, but in some cases few ones are distributed at the ends.

  • Author
    Kulikovskiy and Lange-Bert. 2015
  • Length Range
    8-33 µm
  • Width
    4.5-10.5 µm
  • Striae in 10µm

Original Images

Eolimna metafarta orig desc
Eolimna metafarta orig desc

Cite This Page

Bishop, I. (2019). Eolimna metafarta. In Diatoms of North America. Retrieved June 04, 2020, from https://diatoms.org/species/eolimna_metafarta


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