Diatoms of North AmericaDiatoms of North America

Encyonema minutum var. pseudogracilis

(Cholnoky) Czarn. 1994

Encyonema Minutum Pseudogracilis Guide
  • Category
    Asymmetric Biraphid
  • Length Range
    42-60 µm
  • Width Range
    12.3-13.0 µm
  • Striae in 10 µm
    7-9 at mid-valve; up to 11 at the dorsal apex and 13 at the ventral apex
  • Synonyms
    Cymbella minuta var. pseudogracilis (Cholnoky) Reimer 1975
    Encyonema neomesianum Krammer 1997

Identification

Encyonema minutum var pseudogracilis LM6 Encyonema minutum var pseudogracilis LM3 Encyonema minutum var pseudogracilis LM2 Encyonema minutum var pseudogracilis LM4 Encyonema minimum var pseudogracilis LM7 Encyonema minutum var pseudogracilis LM5 Encyonema minutum var pseudogracilis LM1
View image metadata
Encyonema minutum var. pseudogracilis SEM1

Description

Valves are dorsiventral, with a broadly rounded dorsal margin and a linear ventral margin that expands at the center. Valve apices are rounded to slightly apiculate. Dorsal striae are radiate throughout, and ventral striae are radiate to convergent. Dorsal striae are regularly spaced, while ventral striae vary in density and length across the apical axis. Areolae are coarse and easily visible in LM, measuring 21-24 in 10 µm. A single stigmoid occurs in line with the central dorsal stria. The axial area is narrow near the apices, and gradually widens toward mid-valve. Terminal nodules are clearly visible. The raphe is for the most part lateral, becoming filiform at ends, and its proximal ends are unilaterally deflected toward the dorsal margin.

Autecology

Encyonema minutum var. pseudogracilis has been reported across three continents (Africa, South America, and North America). The species was described from South Africa (Cholnoky 1958) and noted its occurence in weakly acidic freshwater habitats. It has been reported across the eastern United States (Patrick and Reimer 1975). The populations examined for this taxon page were collected in the southeast, from Georgia to North Carolina.

Original Description

  • Basionym
    Cymbella turgida var. pseudogracilis
  • Author
    Cholnoky 1958
  • Length Range
    40-50 µm
  • Width
    9-10 µm
  • Striae in 10µm
    9-11 (mid-dorsal)

Original Images

Cyclotella minuta var. pseudogracilis orig desc
Cymbella turgida var. pseudogracilis orig illus

Cite This Page

Bishop, I. (2017). Encyonema minutum var. pseudogracilis. In Diatoms of North America. Retrieved November 23, 2024, from https://diatoms.org/species/encyonema_minutum_var._pseudogracilis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Encyonema minutum var. pseudogracilis 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.