• Category
  • Length Range
    158.2-262 µm
  • Width Range
    5 µm
  • Striae in 10 µm
    10-11
  • Synonyms
    Ulnaria delicatissima (W.Sm.) Aboal 2003
    Fragilaria delicatissima (W.Sm.) Lange-Bert. 1980
    Synedra acus f. delicatissima (W.Sm.) Krieger 1927

Identification

Description

Valves linear, gradually tapering to short protracted apices. Valves are sometimes weakly curved. Apices are rostrate and ends are rounded, 2.9-3.0 µm wide.

Stria are interrupted by a narrow, linear sternum. Striae are opposite in the valve center and apices, often alternate in the valve away from center and apices. Lineolate areolae are barely visible in LM, occurring 29-31 in 10 µm. Striae extend over the valve/mantle interface and terminate halfway down the valve mantle. Mantle height is approximately 2.5-3.0 µm. The sternum broadens to an elliptic central area that often has ghost striae and is bordered by shortened striae. Each valve has two rimoportulae, one at each apex.

Narrow Ulnaria and Fragilaria species are difficult to identify. In addition, the taxonomic history of U. delicatissima has been complicated by the presence of two different species of Ulnaria on the W. Smith 1853 type slide (Tuji and Houki 2004). Patrick (Patrick and Reimer 1966) published a lectotype, based on a line drawing. However, the identity of U. delicatissima remained unclear until Tuji and Houki (2004) published images from the W. Smith (1853) type slide.

Autecology

Ulnaria delicatissima has been reported across a wide geographic range in the United States, usually occurring in the plankton, although not reaching high abundance (Patrick and Reimer 1966).

Uldelicatissima  Lower48
Credit: USGS BioData
Distribution of Ulnaria delicatissima in rivers of the continental U.S. based on the National Water Quality Assessment program. Retrieved 24 May 2017.
Uldelicatissima  Hawaii
Credit: USGS BioData
Distribution of Ulnaria delicatissima in rivers of Hawaii based on the National Water Quality Assessment program. Retrieved 24 May 2017.
Uldelicatissima  Alaska
Credit: USGS BioData
Distribution of Ulnaria delicatissima in rivers of Alaska based on the National Water Quality Assessment program. Retrieved 24 May 2017.

Original Description

V. elongated. Very narrow, and gradually tapering to somewhat acute extremities. Striae 27 in .001". Length .0048" to .0092". v.s.

Fresh water. Lough Neigh, Dr. Dickie, 1850.

Plate XII. 94.

  • Basionym
    Synedra delicatissima
  • Author
    W.Sm. 1853

Original Images

Smith 1853  Ulnaria Delicatissima Type
Sydelicatissima  Original Image

Cite This Page

Burge, D., Edlund, M. (2017). Ulnaria delicatissima. In Diatoms of North America. Retrieved December 13, 2019, from https://diatoms.org/species/ulnaria_delicatissima

Responses

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