• Category
  • Length Range
    23-57 (inital cells up to 60) µm
  • Width Range
    8-13 µm
  • Striae in 10 µm
    8-11 in the valve center



Valves are moderately dorsi-ventral, with rounded or slightly protracted, blunt apices. The dorsal margin is strongly arched, whereas the ventral margin is flat or slightly convex. The central area is small, elliptical. Two (rarely one or three) stigmata are present at the end of the middle striae. The proximal raphe ends have central pores that curve to the ventral margin. The raphe is lateral, becoming filiform near the distal end. Striae are radiate. The areolae are apically elongated, they number 17-20 in 10 μm.


Original Description

Cymbella subturgidula nov. spec. [Figs 44: 19-21]

Type locality: Korea, Ulchin County, Kyungsang Pukdo, Kwangchun River, slide 1046c IOK.

Valves distinctly dorsiventral, broadly lanceolate, dorsal margin strongly arched, ventral margin moderately convex. Ends not to barely protracted and bluntly rounded. Length 36-37 μm, breadth 10-11 μm, maximal length/breadth ratio 3.7. Axial area narrow, linear or slightly curved. Central area very small, roundish. Raphe somewhat ventrally displaced, distinctly lateral, becoming filiform near the distal and slightly reverse-lateral towards the proximal ends. Proximal raphe ends have distinct central pores, terminal fissures dorsally deflected. Striae radiate in the middle portion, becoming more radiate near the ends, distinctly punctate-lineolate. Two isolated stigmata just at the ends from the middle striae on the ventral side or very slightly separated from these. Striae in the middle portion 10-11/10 μm (dorsal and ventral), becoming up to 15/10 μm towards the ends, puncta about 24 /10 μm.

Differential diagnosis: Distinguished from the other taxa in particular from C. metzeltinii by more finely punctate striae, the smaller central area, the commonly two stigmata and the larger length/breadth ratio.

  • Author
    Krammer 2002

Original Images

Cymbella subturgidula orig illus
Cymbella Subturgidula  Descr

Cite This Page

Potapova, M. (2011). Cymbella subturgidula. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/cymbella_subturgidula


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