Diatoms of North AmericaDiatoms of North America

Pinnularia rexlowei

Potapova, Kersey and Aycock 2023

Pinnularia rexlowei guide
  • Category
    Symmetric Biraphid
  • Length Range
    135–188 µm
  • Width Range
    18–23 µm
  • Striae in 10 µm
    7-8

Identification

Pinnularia rexlowei LM1 Pinnularia rexlowei LM5 Pinnularia rexlowei LM2 Pinnularia rexlowei LM3 Pinnularia rexlowei LM4 Pinnularia rexlowei LM6
View image metadata Type
Pinnularia rexlowei SEM2 Pinnularia rexlowei SEM1

Description

Valves are linear, slightly inflated in the middle, with capitate-cuneate apices, and a length-to-width ratio of 7.6–8.4. The axial area is linear and 1/4–1/3 of the valve width. The central area is roughly elliptical, asymmetrical, wider on the primary valve side, and often barely expanded on the secondary valve side. Striae (alveoli) are weakly radiate at the valve center and parallel to weakly convergent at the apices.

Internal openings of the alveoli are approximately 1/4–1/3 of the alveolus length throughout most of the valve, but longer at the expanded part of valve apices. Under LM their borders form two longitudinal lines: one transects the striae approximately half-way, and the other is 1–3 μm from the valve margin, but often not visible under LM.

The raphe appears lateral or complex in LM, with a sinuous outer fissure, rounded central pores, and question mark-shaped terminal raphe fissures. Short conical spines, straight or slightly bent in the direction of valve apices are present. Spines are located at the valve face–mantle junction, on both sides of the valve, arranged in a slightly wavy row, usually one, but occasionally two per virga or missing on some virgae, absent from valve apices.

Autecology

Pinnularia rexlowei was found in lacustrine deposits and sediment cores of a few New England lakes. The only waterbody where it was encountered in surface sediments was a shallow pond with soft (conductivity 74 μS /cm), slightly acidic (pH 6.2) water and low nutrient concentrations (TP 7 μm/L, TN 369 μm/L).

Original Description

Valves 18–23 μm wide, 135–188 μm long, linear, slightly inflated in the middle, with capitate-cuneate apices (Figs 58–65, 88–90). Valve length-to-width ratio 7.6–8.4. Axial area linear, 1/4–1/3 the valve width. Central area roughly elliptical, asymmetrical, wider on the primary valve side, often barely expanded on the secondary valve side. Striae (alveoli) weakly radiate at the valve centre and parallel to weakly convergent at the apices, 7–8 in 10 μm. Inner openings of the alveoli approximately 1/4–1/3 of the alveolus length throughout most of the valve, but longer at the expanded part of valve apices (Fig. 102). Under LM their borders form two longitudinal lines: one transects the striae approximately half-way, and the other is 1–3 μm from the valve margin, often not visible under LM (Figs 88–90). The raphe appears lateral or complex in LM, with a sinuous outer fissure, rounded central pores and question mark-shaped terminal raphe fissures (Figs 98, 99). Short conical spines, straight or slightly bent in the direction of valve apices are present (Fig. 99). Spines are located at the valve face–mantle junction, on both sides of the valve, arranged in a slightly wavy row, usually one, but occasionally two per virga or missing on some virgae, absent from valve apices.

  • Basionym
    Pinnularia rexlowei
  • Author
    Potapova, Kersey and Aycock 2023
  • Length Range
    135–188 µm
  • Width
    18–23 µm
  • Striae in 10µm
    7-8

Original Images

Prex Orig Ill

Cite This Page

Potapova, M. (2023). Pinnularia rexlowei. In Diatoms of North America. Retrieved April 27, 2024, from https://diatoms.org/species/pinnularia-rexlowei

Responses

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