Valves have a distinct circular center and a marginal ring of striae. The central area is approximately 1/3-1/2 of the valve face. The central area is tangentially undulate, with the degree of undulation ranging from slight to distinct. The central area is smooth, but may have verrucae or grooves on the valve surface. The marginal striae are broadest at valve/mantle interface and taper near the central area. A circular shadow line, appearing as a faint ring, crosses the striae. Under SEM, the striae are seen to be composed of 2-3 areolae near the center valve and 4-5 areolae toward the margin. Internally, the shadow line can be seen to be the image of the inner border of the internal alveolae openings. These openings are quite small in this taxon, so that striae are mostly occluded. Numerous marginal fultoportulae are evident. The fultoportulae are short, with 2 satellite pores. A single rimoportula is present on the valve mantle, with the internal opening oriented parallel to the margin.
This taxon is of broad occurrence in the plankton of lakes and large rivers and is known to prefer alkaline waters.
Lowe, R., Manoylov, K. (2011). Cyclotella distinguenda. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/cyclotella_distinguenda
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cyclotella distinguenda 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.
