Valves are lanceolate and dorsiventral with bluntly rounded apices in the largest specimens and narrowly rounded apices in smaller specimens. The dorsal margin is moderately arched; the ventral margin is slightly convex, appearing somewhat tumid in the middle. The axial area is a bit wider than the raphe and bowed, located just ventral of the valve mid line. The central area is a slightly wider continuation of the axial area, otherwise undistinguished. The raphe is lateral, becoming reverse-lateral near the proximal ends. Proximal raphe ends are deflected ventrally and terminate in weakly inflated pores. Terminal raphe fissures are deflected dorsally at about 45 degrees. Striae are parallel to weakly radiate near the valve center, becoming strongly radiate near the apices. Areolae are rather coarse and number 18-22 in 10 µm. A single isolated stigma (sometimes 2) is located at the proximal end of the median ventral stria.
The specimens illustrated here were collected from a spring in the Bitterroot Mountains of western Montana. The water quality of this spring is unknown. In European waters, it grows on epiphytic and epilithic habitats in oligotrophic waters with low to average electrolyte content (Krammer 2002). In temporary Mediterranean streams, this taxon was reported exclusively from reference quality sites, as defined by land use (Delgado et al. 2012).
Bahls, L. (2016). Cymbella vulgata. In Diatoms of North America. Retrieved October 30, 2024, from https://diatoms.org/species/cymbella_vulgata
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbella vulgata 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.