Valves are linear-lanceolate with convex sides and short, capitate apices. Apices are about one-half the width of the valve. Valve length-to-width ratio ranges from 4.0 to 4.7. The axial area is narrow and nearly linear. The central area is small and elliptical and bordered by alternately long and short striae. The raphe is filiform with a slight "kink" (SEM) about halfway to the apices. Proximal raphe ends are straight and slightly expanded. Distal raphe ends are strongly curved towards the secondary side, where Voigt discontinuities are evident in SEM. In LM, striae are easy to distinguish only in the central area. Striae are radiate, becoming convergent near the apices. Striae are composed of irregular series of dots and dashes which form jagged and faint longitudinal lines. The striae stop short of the valve mantle, where a hyaline line completely encircles the valve along the margins (SEM).
Navicula subtilissima was described by Cleve from material collected in Lake Imandra, Russian Lapland, at approximately 68 degrees north latitude. Fallu et al. (2000) reported this taxon from lakes in northern Québec and Labrador. In the United States, Stoermer et al. (1999) reported Kobayasiella subtilissima (as Kobayasia subtilissima) from the Great Lakes. We have six records for this species in the Montana Diatom Collection, from California, Idaho, Montana, and Wyoming. One of these records is for Drosera Pond on the Indian Meadows Research Natural Area, Helena National Forest, Montana, where it occurs in association with K.micropunctata, K. okadae, and K. parasubtilissima. Here the pH measures 8.46 and specific conductance measures 19 µS/cm.
Bahls, L. (2012). Kobayasiella subtilissima. In Diatoms of North America. Retrieved December 03, 2024, from https://diatoms.org/species/kobayasiella_subtilissima
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Kobayasiella subtilissima 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.
