• Category
  • Length Range
    37.6-58.2 µm
  • Width Range
    13.7-18.2 µm
  • Striae in 10 µm



Valves are widely lanceolate, with acutely rounded apices. The raphe is undulate and complex. The proximal raphe ends are expanded. The axial area is relatively narrow and slightly lanceolate. The central area is a small irregular stauros, delimited by 5-7 unevenly shortened striae on each side. Striae are radiate throughout, becoming most strongly radiate at the apices. Striae are uniseriate in the central region, with nearly square areolae arranged in distinguishable pairs, 22-24 areolae in 10 µm. Striae become biseriate, with more densely spaced areolae, 25-28 areolae in 10 µm, at the valve margin.


Aneumastus caroliniana was described from South Carolina, but has been reported from the Great Lakes (Stoermer et al. 1999). Specimens shown here were collected from two reference-quality streams in West Virginia. This species tends to be uncommon and low in abundance.

Original Description

Navicula caroliniana

Valva lanceolata, apicibus leniter attenuatis, semirostratis, rotundis. Area axiali angusta. Raphae undulato. Area centrali transversa, inaequali in forma. Striis radi-antibus per valvam; inaequali in longitudine circa aream centralem; interdum vicissim longioribus et brevioribus. Striis fractis constiuere lineas inaequales et longitudinales. Striae, 11-12 in 10 μ. Longitudo, 44-45 μ (specimen typicum, 45 μ).Latitudu, 15-16 μ (specimen typicum, 15 μ).

Valve lanceolate with slightly attenuate, semi-rostrate, rounded ends. Axial area narrow. Raphe undulate. Central area transverse, irregular in shape. Striae radiate throughout the valve; irregular in length about central area; may be alternately long and short; broken to form irregular longi-tudinal lines. On the margins of the valve, the striae sometimes give the appearance of being composed of two rows of puncta. Striae, 11-12 in 10 μ. Length 44-45 μ (type, 45 μ). Breadth 15-16 μ (type, 15 μ).

This specimen belongs in the same group as N. tuscula. It is similar to N. constantini Skv. in both the structure of the striae and the raphe, which is undulate.

Specimen illustrated.--A-G.C. 44496 Type locality.--South Carolina, Aiken County, Savannah River at Mile 175 from the mouth of the river, October, 1953. Distribution.--Known only from the type locality.

  • Basionym
    Navicula caroliniana
  • Author
    Patrick 1959
  • Length Range
    44-45 µm
  • Width
    15-16 µm
  • Striae in 10µm

Original Images

Aneumastus carolinianus orig illus
Aneumastus carolinianus orig descr

Cite This Page

Polaskey, M. (2017). Aneumastus carolinianus. In Diatoms of North America. Retrieved June 13, 2024, from https://diatoms.org/species/aneumastus_carolinianus


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