• Category
  • Length Range
    46.5-90.8 µm
  • Width Range
    4.3-7.6 µm
  • Striae in 10 µm
  • Synonyms
    Fragilaria pulchella (Ralfs ex Kütz.) Lange-Bert.
    Synedra pulchella (Ralfs ex Kütz.) Kütz.



Valves are elongate and linear to lanceolate, with capitate to rounded poles. Valves have a central area with a distinct fascia. The fascia may have ghost striae; these are indentations within the valve that do not open to the surface. The axial area is linear. The striae are parallel and clearly punctate. Each stria at the middle of the valve has about 5-6 areolae, striae at apices have 2-4 areolae. There is one rimoportula at each apex that is diagonal to the sternum, though this feature can be difficult to distinguish on light microscope on some specimens.

Larger specimens may be slightly sigmoid at the poles, and the shortest valves may have one pole slightly curved. Some valves can be slightly convex in girdle view. In some valves, the striae can diverge and become nonparallel. The sternum can be sigmoidal to irregular in shorter specimens. The variations in morphology may be indicative of multiple forms through Ctenophora pulchella life cycle, environmental conditions at the sampling site, and/or multiple varieties present within the sample.


Ctenophora pulchella was observed in brackish waters along coastal regions, as well as freshwater habitats with higher mineral content. The specimens imaged here are from a composite benthic sample from a heavily modified urban stream, Collins Channel from Orange County, California. Water pH at the site was 8.08, dissolved oxygen content was 5.73 mg/mL, conductivity was of 2946 µS/sm, and salinity was 1.54 ppt. Cells attach to macrophytes and other surfaces via a mucilage pad at one end and form tuft-shaped colonies.

Original Description

  • Basionym
    Synedra pulchella
  • Author
    Ralfs ex Kütz. 1844

Original Images

Jkjctenophora Pulchella Original
Synedra Pulchella Original

EMAP Assessment

EMAP Distribution

Ctenophora Pulchella   Ralfs Ex  Kùtzing   Williams Et  Round 20
Map 20

Response Plots

Ctenophora Pulchella

Cite This Page

Jones, J. (2013). Ctenophora pulchella. In Diatoms of North America. Retrieved July 18, 2018, from https://diatoms.org/species/ctenophora_pulchella


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