Valves are lanceolate-elliptic, with a slight concavity in the valve face. Apices are produced and subrostrate. The central area is variable in size, but often large and oval to rectangular. Between the axial area and margin, each stria is sigmoid. Near the central area, the striae are shorter (central area larger). For most of the valve, the striae are radiate. Near the apices, the striae are convergent. The raphe is linear. Proximal raphe ends are expanded and unilaterally deflected. Distal raphe ends are unilaterally hooked.
Pinnunavis elegans is likely a species complex and will require more work to resolve uncertainty associated with size range and morphological variation.
Note that Pinnuavis elegans is a misspelling of Pinnunavis elegans and these orthographic variants are considered the same taxon (Moe and Silva 2011).
Specimens illustrated here were collected from a sediment core taken at a site along western Montague Island, Prince William Sound, Alaska at a depth of 349-350 cm. The age of the sediment at this depth was dated, using radiocarbon, ~2,600 years BP. Pinnunavis elegans was found co-occurring with freshwater-brackish species that prefer high acidity.
This taxon is reported to favor acidic and relatively dry (<40%) soils with high chloride (up to 700 mg/l) and phosphate (up to 7 mg/l) concentrations (Van de Vijver et al. 2002)
Other ecological records include Kerguelen (Bourrelly and Manguin 1954) and Campbell Island (Hickmann and Vitt 1973).
15. Navicula elegans, n. sp. V. elliptical acuminate ; striae distinct, 24 in .001”, waved, radiate, absent around the central nodule. Length .0020” to .0032”. v.v.
Marine or brackish water. Poole Bay, June 1849, W. Sm. Cockerham Marsh, Lancashire, Mr. Johnson.
Plate XVI. 137.
DePaolis, J. (2023). Pinnunavis elegans. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/pinnunavis-elegans
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Pinnunavis elegans 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.