Diatoms of North AmericaDiatoms of North America

Pinnularia divergentissima var. subrostrata

A.Cleve 1898

Pinnularia divergentissima subrostrata guide
  • Category
    Symmetric Biraphid
  • Length Range
    28-38 µm
  • Width Range
    5.5-6.1 µm
  • Striae in 10 µm
    12-14
  • Synonyms
    Navicula divergentissima var. subrostrata (A.Cleve) Peragallo
    Pinnularia subrostrata var. subrostrata (A.Cleve) A.Cleve

Identification

Pinnularia divergentissima subrostrata LM6 Pinnularia divergentissima subrostrata LM1 Pinnularia divergentissima subrostrata LM5 Pinnularia divergentissima subrostrata LM3 Pinnularia divergentissima subrostrata LM4 Pinnularia divergentissima subrostrata LM2 Pinnularia divergentissima subrostrata LM7
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Pinnularia Divergentissima Subrostrata SEM PF23a 001

Description

Valves are linear, with slightly convex margins and broadly capitate ends. The axial area is narrow and linear. The central area is a broad fascia reaching the valve margin. The raphe is filiform. Proximal raphe ends are teardrop-shaped and deflected to the primary valve side. Striae are strongly radiate near the valve center, becoming convergent about halfway to the apices. The change in striae direction is abrupt, so that two groups of striae form an acute angle where they meet.

This taxon has been confused with several other taxa. Krammer and Lange-Bertalot (1986) included P. perinterrupta Krammer (figs 185: 11-13) in their treatment of P. subrostrata (A. Cleve) A. Cleve (= P. divergentissima var. subrostrata).

Antoniades et al. (2008) mentioned that this taxon was initially identified as P. perinterrupta in their dataset, however, their images of P. perinterrupta (figs 63:2-3) show P. lacunicola (= P. krammeri).

Autecology

Images of specimens on this page are from the Alaskan high arctic, collected by L. Freese (Patrick and Freese 1961).

This taxon is reported  from arctic and subarctic regions of Europe and North America (Krammer 2000, Antoniades 2008)

Original Description

Ends of the valve rostrate-capitate

  • Author
    A.Cleve 1895

Original Images

Pinnularia divergentissima subrostrata orig illus
Pinnularia divergentissima subrostrata orig desc

Cite This Page

Leppik, S., Potapova, M. (2024). Pinnularia divergentissima var. subrostrata. In Diatoms of North America. Retrieved April 22, 2025, from https://diatoms.org/species/329255/pinnularia-divergentissima-var-subrostrata

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Pinnularia divergentissima var. subrostrata 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.