Diatoms of North AmericaDiatoms of North America

Cavinula pseudoscutiformis

(Hust.) D.G.Mann and Stickle in Round, R.M.Crawford and D.G.Mann 1990

Cavinula Pseudoscutiformis Guide
  • Category
    Symmetric Biraphid
  • Length Range
    5.5-10.0 µm
  • Width Range
    4.9-9.3 µm
  • Striae in 10 µm
    16-24 in the center valve

Identification

Cavinula pseudoscutiformis LM2 Cavinula pseudoscutiformis LM1 Cavinula pseudoscutiformis LM4 Cavinula pseudoscutiformis LM5 Cavinula pseudoscutiformis LM3
View image metadata
Cavinula pseudoscutiformis SEM2 Cavinula pseudoscutiformis SEM1

Description

Valves are nearly round. Areolae are approximately 36 in 10 μm. The axial area is narrow and linear and extends onto the valve margins at the apices; the central area is small and nearly indistinguishable from the axial area. The raphe is filiform with slightly expanded central raphe ends. The striae are punctate and strongly radiate. Striae are incomplete in the central valve, that is, several are short and do not extend from the central area to the valve margin. The stria density increases towards the apices. The external openings of the areolae are round. Internally, the areolae are elongated. Internally, the raphe slit is narrow at proximal and terminal ends. The helictoglossae are reduced.

Autecology

This taxon displays a circumboreal distribution (Foged 1981, Camburn and Charles 2000, Fallu et al. 2000, Bahls 2023, Barinova et al. 2023). In North America, this taxon has been reported with light micrographs from Alaska (Foged 1981), the northeastern US (Camburn and Charles 2000), Québec and Labrador (Fallu et al. 2000), the Central Canadian Arctic (Rühland et al. 2003), the Great Lakes (Reavie 2022), Rocky Mountains, Cascades, and Olympic ranges (Bahls 2023).

In the Great Lakes National Parks (Edlund et al. 2009, 2011, 2012, 2013), this taxon is rare (<1% relative abundance) in Voyageurs (Ryan, Cruiser, Ek, Mukooda, Brown) and the St. Croix National Scenic Riverway (Lake St. Croix).

This taxon prefers circumneutral waters (Patrick and Reimer 1966, Foged 1981, Bahls 2023, Barinova et al. 2023) with low nutrients and conductivity (Foged 1981, Bahls 2023, Barinova et al. 2023). Patrick and Reimer (1966) reported this taxon to occasionally occur in waters of high mineral content. This taxon is reported to prefer cool waters (Patrick and Reimer 1966, Bahls 2023).

Many research groups have used this taxon as an indicator organism and published regional environmental optima and tolerances including:

Sovereign (1958): pH – 6.5 to 9.0 for populations from the Pacific Northwest.

Camburn and Charles (2000): pH – 6.65 +/- 0.43, Acid Neutralizing Capacity – 62 +/- 46 µeq/L, Total Aluminum – 43 +/- 70 µg/L, Dissolved Organic Carbon (DOC) – 95 +/-128 µmol/L, Total Phosphorus (TP) – 7.94 +/- 2.93 µg/L for populations from lakes in the Northeastern US.

Fallu et al. (2000): DOC – 5.29 +/- 1.43 mg/L for populations from Québec. Color – 19 +/- 2.7 Pt units, Alkalinity – 61 +/- 2.7 µeq/L for populations from Labrador.

Lim et al. (2001): TN 0.745 +/- 0.139 mg/L for populations from Bathurst Island in the Canadian Arctic.

Rühland et al. (2003): Dissolved Inorganic Carbon – 1.1, Total Nitrogen (TN) – 0.314 mg/L, DOC – 7.0 mg/L, Depth – 4.0 m, SiO2 – 0.3 mg/L for populations from the Central Canadian Arctic.

Bahls (2023): Conductivity – 58 µS/cm, pH – 7.3, Temperature – 15.9 °C, TN – 0.250 mg/L, TP – 21 µg/L for populations from mountains in the Western US.

Barinova et al. (2023): pH – 6.2-8.4 for populations from the coast of Tiksi Bay in the Russian Arctic.

Original Description

Schalen breit-elliptisch, fast kreisförmig, mit breit gerundeten Polen, 9-15 µ lang, 7-13 breit. Axialarea eng, um den Mittelknoten wenig erweitert. Zentralporen der Raphe entfernt gestellt. Transapikalstreifen durchweg radial, zart, etwa 24 in 10 µ, in der Mitte von ungleicher Länge, zart punktiert.

  • Basionym
    Navicula pseudoscutiformis
  • Author
    Hust. in Pascher 1930
  • Length Range
    9-15 µm
  • Width
    7-13 µm
  • Striae in 10µm
    24

Original Images

Img 0417
Img 0418

Citations & Links

Citations

Links

  • Index Nominum Algarum
    Original, Transfer
  • North American Diatom Ecological Database
    NADED ID: 195003

Updates

Dec 02, 2024 - Addition of Autecology

From 2011 until 2024 the autecological information on this taxon page was limited. As of this update, information on ecology, biogeography, and environmental optima have been added. - Lane Allen & Mark Edlund

Cite This Page

Otu, M., Spaulding, S., Allen, L., Edlund, M. (2011). Cavinula pseudoscutiformis. In Diatoms of North America. Retrieved December 03, 2024, from https://diatoms.org/species/cavinula_pseudoscutiformis

Responses

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