Valves are lanceolate with short, subrostrate, and broadly rounded apices. The axial area is about three times wider than the raphe. The central area is a stauros, somewhat wider toward valve margins and occasionally containing short marginal striae. External raphe fissures are lateral. Proximal raphe endings are somewhat inflated and curved to the secondary side. Terminal raphe fissures are hooked, the hooks opening towards the secondary side. Striae are radiate throughout, more so near the apices. Areolae are distinct and number 15-18 in 10 µm.
Stauroneis heinii is widely distributed in ponds, small lakes, and wetlands at lower elevations in the Northern Rockies. Available water quality data suggest that this taxon has a relatively broad ecological amplitude, with pH ranging from 5.5 to 8.5 (mean = 6.5) and specific conductance ranging from 8 to 257 µS/cm (mean = 74 µS/cm). Hein (1990) reported this taxon (as S. phoenicenteron) from Adak Island, Alaska.
Valvae stricte lanceolatae apicibus minime curte protractis et late rotundatis, 125-200 µm, 22-29 µm latae. Fissurae raphis conspicue laterales sitae inter se extremis centralibus distincte reverse-lateralibus poris centralibus unilateraliter declinatis. Area axialis satis lata ad mediam versus sensim dilatata. Area centralis fasciam formans fere anguste rectangulatam sive ad margines paulo dilatatam. Striae transapicales modice radiantes in media parte magis in partibus distalibus, 15-18 in 10 µm. Puncta striarum 16-18 in 10 µm.
Bahls, L. (2011). Stauroneis heinii. In Diatoms of North America. Retrieved October 13, 2024, from https://diatoms.org/species/stauroneis_heinii
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Stauroneis heinii 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.