Frustules are cuneate, in both valve and girdle view. Valves are heteropolar in the headpole and heterovalvar in the raphe system. The headpole shape is variable and may be rounded, subcapitate, rostrate, or truncate-spatulate. The footpole is narrow and rounded. Short spines are present along the valve margin. A narrow sternum runs the length of the valve. The raphe system differs on each valve. One valve has two raphe branches, extending along the sternum from each pole approximately one third of the valve length. The other valve has a rudimentary raphe evident at the poles, or the raphe may be absent. The proximal raphe ends curve slightly to one side.
Striae are parallel, transverse, irregularly spaced, becoming radial or irregular at the poles. Rimoportulae are present, one at the headpole and one at the footpole.
In contrast to populations on the east coast of the US, the Waldo Lake, Oregon, populations shown here have a highly variable shape of the headpole. Over the size range of the populations, headpole shape shows no relation to valve width or to valve length (see size series image in AUTECOLOGY section). The size series supports a single, variable species rather than multiple taxa.
Of the four species of Peronia, only P. fibula has been verified in North America. Patrick & Reimer (1966) erroneously assigned Meridion intermedium to Peronia intermedium, which would have made this the second species of Peronia. However, M. intermedium, a synonym of M. circulare, lacks a raphe system.
The specimens shown here were collected from the margin of Waldo Lake, Oregon, in September 2015 and July 2016. The samples consisted of rock scrapings, clumps of cyanobacterial mat, and leaves of a submerged liverwort (Division Bryophyta, Class Hepaticae). Cells were found on the liverwort but no stalks from the cells were noticed. Several Eunotia species appeared in the sample, including E. bactriana, E. faba, E. gibbosa, E. monodon, E. parallela, and E. serra. Elsewhere in the United States, P. fibula has been found in fresh, shallow water in Delaware, South Carolina, Florida, South Dakota, and Nebraska (Patrick and Reimer 1966). This species has also been found in Europe (Williams and Reid 2008).
Waldo Lake lies in a glaciated basin on the Cascade Crest in Oregon at 1650 m (5413 feet). It occupies 84% of its drainage basin and receives most of its water from snow melt. Sytsma et al. (2004) found this lake to be acidic and very oligotrophic. Field measurements of pH from 1998 through 2003 averaged 5.9. Specific conductance in 2002 and 2003 averaged 2.9 μS/cm. Between 1996 and 2003 the average alkalinity was 2.34 mg CaCO3/L. From 1986 to 1998, total phosphorus averaged 2.9 µg/L. In 2000, dissolved nitrogen was at or slightly above the detection limit of 1 µg/L. Silica averaged 0.24 mg/L from 1996 to 2003.
Bahls, L., Kimmich, R. (2017). Peronia fibula. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/51785/peronia_fibula
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Peronia fibula 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.
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