Diatoms of North AmericaDiatoms of North America

Cocconeis neodiminuta

Krammer 1990

Cocconeis neodiminuta guide
  • Category
    Monoraphid
  • Length Range
    7-18 µm
  • Width Range
    5-9 µm
  • Striae in 10 µm
    Raphe valve 24-32, rapheless valve 11-14

Identification

Cocconeis Neodiminuta Lm04 Cocconeis Neodiminuta Lm06 Cocconeis Neodiminuta Lm02 Cocconeis Neodiminuta Lm03 Cocconeis Neodiminuta Lm05 Cocconeis Neodiminuta Lm01
View image metadata
Cocconeis neodiminuta SEM4 Cocconeis neodiminuta SEM3 Cocconeis Neodiminuta Sem01 Cocconeis Neodiminuta Sem02

Description

Valves are elliptic. The raphe valve has a narrow axial area and small, circular central area. The raphe is straight and filiform. Striae are 24-32 in 10 µm, radiate and interrupted by a hyaline smooth submarginal ring. The areolae are distinguished under LM, 25-32 in 10 µm.

The rapheless valve has a relatively wide lanceolate axial area. Striae are slightly radiate in the center of the valve, becoming radiate toward the ends. Each stria is composed of two to five (typically three) large, transversely rectangular areolae. Often, the central striae are separated by wider virga on one side of the valve. Externally, small punctae, which do not penetrate the valve are observed between areolae in the axial area (SEM).

Autecology

This taxon has been reported with light micrographs from lakes in the Northeastern US (Camburn and Charles 2000), Rocky Mountains, Great Plains, Cascades, Sierras, and coastal streams (Bahls 2021). This taxon has been recorded in streams and rivers of northern California.

In the Great Lakes National Parks (Edlund et al. 2009, 2011, 2012, 2013), this taxon is common (5-25% abundance) in sediment core material from St Croix Riverway, and Pictured Rocks (Beaver Lake) and uncommon (1-5% abundance) to rare (0.1-1% abundance) at Pictured Rocks (Grand Sable Lake), Voyageurs (Mukooda Lake), and Isle Royale (Richie Lake).

This taxon is reported to prefer streams with cold alkaline water of low conductivity and nutrient content (Bahls 2021).

Several research groups consider this taxon an indicator organism and published regional environmental optima and tolerances including:

Bahls (2021): Conductivity - 199 µS/cm, pH - 7.9, Temperature - 11.3°C, Total Nitrogen - 0.16 mg/L, Total Phosphorus - 19 µg/L for populations from Northwestern North America.

Original Description

Valvi parvulis, late-ellipticis, 8-18 µm longis, 6-9 µm latis. RLV striis valide punctatis, 12-15/10 µm, area valvae angusta vel angusto-lanceolata; RV striis tenuis, 24-32/µm, puncta 25-32/10 µm, area valvae angusta, raphe tenuisima.

  • Author
    Krammer 1990
  • Length Range
    8-18 µm
  • Width
    6-9 µm
  • Striae in 10µm
    12-15

Original Images

Cocconeis neodiminuta orig desc

Citations & Links

Citations

Links

  • Index Nominum Algarum
    Original
  • The Academy of Natural Sciences, Drexel University
    Link

Updates

Feb 05, 2026 - Addition of Autecology

From 2021 until 2026, 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 and Mark Edlund

Cite This Page

Bishop, I., Edlund, M., Allen, L. (2021). Cocconeis neodiminuta. In Diatoms of North America. Retrieved March 24, 2026, from https://diatoms.org/species/61705/cocconeis-neodiminuta

Responses

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