• Category
  • Length Range
    29.4-33.2 µm
  • Width Range
    12.5-15.7 µm
  • Striae in 10 µm
    17 in the center, 20 near the ends
  • Reported As
    Cosmioneis pusilla (Witkowski et al. 2000 Pl. 107, figs 1,2,12,13)
    Cosmioneis pusilla (Krammer and Lange-Bertalot 1997 Pl. 57, fig. 8)

Identification

Description

Valves are citriform, with broadly rounded margins. The ends are short, narrow and rostrate. The axial area is narrow, expanding to rounded central area. The proximal raphe ends are slightly expanded. The distal raphe ends are curved in the same direction. Internally, the raphe ends are anchor-shaped. Striae are punctate and radiate, curving from the margin toward the center of the valve. Striae are 17 in 10 μm in the center, becoming finer at the ends (20 in 10 µm). Areolae number 16 in 10 µm and are round toward the valve ends, becoming transversely elongated near the center.

Autecology

Populations of C. citriformis from Hawai’i are found in fresh water, primarily waterfall spray zones and wet walls.

Original Description

Valves are citriform with broadly rounded margins curving to short narrow rostrate ends. Valves are 26.5-34 μm long and 12.2-15.7 μm wide. The axial area is narrow expanding to rounded central area. The proximal raphe ends are slightly expanded on the valve surface in pyriform depressions. The distal raphe ends are curved in the same direction. Internally, raphe ends are anchor-shaped. Striae are punctate, and radiate, curving from the margin toward the center of the valve. Striae are 17 in 10 μm in the center becoming finer at the ends (20/10µm). Puncta number 16/10µm and are round toward valve ends becoming transversely elongated near center.

  • Author
    A.R.Sherwood and R.L.Lowe in R.L.Lowe and A.R.Sherwood 2010
  • Length Range
    26.5-34 µm
  • Width
    12.2-15.7 µm
  • Striae in 10µm
    17 in center, 20 near the ends

Cite This Page

Lowe, R. (2011). Cosmioneis citriformis. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/cosmioneis_citriformis

Responses

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