• Category
  • Length Range
    20-49.5 µm
  • Width Range
    4.7-7.4 µm
  • Striae in 10 µm
    17-24 dorsal, 19-27 ventral
  • Synonyms
    Delicata delicatula Krammer
    Cymbella delicatula Kütz.



Valves are lanceolate and dorsiventral. Apices are acutely rounded, sometimes apiculate and may be bent dorsally. The axial area is relatively wide and continuous with a somewhat wider but undifferentiated central area. The raphe is lateral, becoming filiform at the distal ends, which are deflected dorsally. Proximal raphe ends are reverse-lateral and deflected ventrally. Striae are radiate throughout and more widely-spaced near the valve center. Areolae cannot be resolved with a light microscope.


This taxon is widely distributed in lakes and mountain streams in western Montana and elsewhere in the western United States. It is most often found in the phytobenthos of alkaline waters of moderate conductivity.

Delicata Delicatula Map Cropped
Credit: Montana Diatom Database
Distribution of Delicatophycus delicatula in the northwestern United States.
Delicata Delicatula Ecology
Credit: Montana Diatom Database
Abundance-weighted mean values for selected variables associated with collections of Delicatophycus delicatula.

Original Description

Cymbella Delicatula Origdesc
  • Basionym
    Cymbella delicatula
  • Author
    Kütz. 1849

Original Images

Cymbella Delicatula Origdesc


Apr 19, 2024 - Correction of species epithet

From August 22, 2023 to April 18, 2024, this taxon appeared as Delicatophycus delicatula. The species epithet is now corrected to D. delicatulus. - S. Spaulding

Aug 22, 2023 - Transfer from Delicatula to Delicatophycus

From November 2018 until August 2023, the taxon on this page appeared as Delicata delicatula Krammer 2003. Following Wynne (2019) the name Delicatophycus delicatula M.J.Wynne 2019 is a replacement name. - S. Spaulding

Cite This Page

Bahls, L. (2017). Delicatophycus delicatulus. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/delicatophyus_delicatulus


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