Valves are broadly linear with parallel margins and obtusely rounded to cuneate apices. The raphe is straight and positioned between the two longitudinal canals. The raphe sternum fills a straight and narrow axial area, which is confluent with a somewhat wider elliptic central area. Proximal raphe ends are unilaterally deflected and terminate at the first row of areolae. Distal raphe fissures are bifurcate and the two branches separate at a wide angle. Striae are weakly curved near the valve center, otherwise straight, and radiate throughout, becoming almost parallel near the apices. Central striae are more distantly spaced that in the rest of the valve. Areolae in the central striae appear larger and more distinct than areolae in more distal striae. External areola openings are simple and round to lineolate. Lineolate openings may be oriented apically, transapically or diagonally depending on their location. Internally, proximal raphe ends are simple and terminate at a central rectelevatum. Distal raphe ends terminate in helictoglossae.
Muelleria tetonensis was described from a sample of benthic algae collected near the shore of a small alpine tarn in the northern part of Grand Teton National Park, Wyoming (photos below). Also found in this sample were Muelleria gibbula and Muelleria spauldingiae.
Valves are linear-elliptic with parallel margins and obtusely rounded to cuneate apices. Valve length 27.2-52.6 μm; valve width 8.6-11.7 μm. The raphe is straight and filiform between two thickened longitudinal ribs, which occupy a narrow axial area. Proximal raphe ends are bent to the same side within a small elliptic central area. Striae are straight and radiate throughout. Areolae in the central striae appear larger and more distinct than areolae in more distal striae. Striae number 16-20 in 10 μm at valve center, 20-24 in 10 μm at the apices.
Bahls, L. (2015). Muelleria tetonensis. In Diatoms of North America. Retrieved September 07, 2024, from https://diatoms.org/species/muelleria_tetonensis
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Muelleria tetonensis 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.