• Category
  • Diameter
    8.4-19.5 µm
  • Reported As
    Chaetoceros elmorei (Boyer 1914)



Cells form filamentous colonies, with neighboring valves linked by twisted setae that extend from the pole of each valve. Valves and setae are lightly silicified. Valves are elliptic. Dissociated frustules result in neighboring valves remaining connected valve face to valve face. The valve face of the intercalary cells are slightly convex. The terminal frustules of colonies have concave valve faces. The valve face lacks distinct ornamentation. A central process, however, (a rimoportula?) may aid in filament formation. The setae of the terminal valve are bent strongly away from the colony.

Internally formed resting spores (endogenous spores) are heavily silicified. Resting spores have a convex primary valve, and secondary valve with a prominent raised annulus.

Typical diatom sample preparation, such as hydrogen peroxide and nitric acid treatments, often dissolves the organic material that supports the lightly silicified valves and filaments.

The taxonomy of North American Chaeotoceros, particularly C. mueller and C. elmorei, has received attention (Johansen and Rushforth 1985, Rushforth and Johansen 1986, Johansen and Boyer 1995). Rushforth. Here we follow the conclusions reached by Johansen et al. (1990) who proposed synonymy of C. muelleri and C. elmorei based on culture studies. In culture, C. muelleri (single cells) and C. elmorei (chains) formed from the same clones. Chaetoceros muelleri is the older valid name, and has nomenclatural priority.


Chaetoceros muelleri is a colonial planktonic species most often found in endorheic saline environments, such as Devil's Lake, North Dakota (Boyer 1914 as Chaetoceros elmorei). Anderson (1958, as C. elmorei) found C. muelleri plankton abundance peaked in mid-summer in saline lakes of Washington state. Bailey (1922, as C. elmorei) reports this taxon from saline lakes in Saskatchewan. Wang et al. (2014) reported Chaetoceros muelleri in saline ponds in California. In a study of inland saline lakes on the Northern Great Plains, C. muelleri was most associated with sulphate-based salinity (Saros and Fritz 2002, as C. elmorei). A single endogenous resting spore is produced by each cell presumably as a dormancy response to inimical conditions; spores are widely used as an indicator of salinity in paleoclimate projects (Fritz et al. 1991).

Chelmorei   Ill2006 56 266 9 0  Colony
Credit: Image from ILL 2006-56
Chelmorei  Usgsbiodata
Credit: USGS/Biodata
The distribution of Chaetoceros elmorei in streams of the contiguous 48 United States. Accessed on 7 June 2017.

Original Description

  • Author
    Lemmerm. 1898
  • Length Range
    9-10 µm
  • Width
    7 µm

Original Images

Lemmerman 1898  Chaet Muelleri Fig
Screen  Shot 2017 07 03 At 4 21 09  Pm

Citations & Links



  • Index Nominum Algarum
  • CAS
  • North American Diatom Ecological Database
    NADED ID: 15002

Cite This Page

Burge, D, and Edlund, M. (2017). Chaetoceros muelleri. In Diatoms of North America. Retrieved August 19, 2018, from https://diatoms.org/species/chaetoceros_muelleri


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