• Category
  • Length Range
    26.5-64.9 (initial valve) µm
  • Width Range
    8.8-13.0 (initial valve) µm
  • Striae in 10 µm
    9-13 dorsal, 12-14 ventral

Identification

Description

Valves are dorsiventral and rhombic-lanceolate with acutely rounded apices. The dorsal margin is strongly arched; the ventral margin is weakly convex with a tumid center. The axial is relatively wide. The central area is a somewhat wider than the axial area. The raphe is distinctly lateral. The raphe is weakly lateral, with ventrally deflected proximal raphe ends. The proximal raphe teminates with slightly inflated pores. Distal raphe fissures are deflected dorsally. Striae are radiate, becoming more strongly radiate near the valve apices. Areolae are distinct in LM and number 22-26 in 10 µm. A stigma is absent.

Note that using the optics of the time, Østrup (1910) perceived a single isolated stigma on the ventral side of the central nodule, hence the name stigmaphora or “stigma-bearing”. Using modern optics, Krammer (2002) was not able confirm the presence of a stigma on the type specimens, nor has a stigma been found in any of the other populations that have been examined.

Autecology

The images of Cymbella stigmaphora on this web page are from a mountain stream and a mountain lake in northwestern Montana. The lake, Lower Saint Mary Lake on the Blackfeet Indian Reservation, has a pH of 8.00 and conductivity of 143 µS/cm. Besides the type locality in Denmark, Krammer (2002) reports this species from mesotrophic lakes in the lower Alps.

Original Description

  • Author
    Østrup 1910
  • Length Range
    56 µm
  • Width
    14 µm
  • Striae in 10µm
    7-8

Original Images

Cymbella stigmaphora orig illus
Cymbella stigmaphora orig desc

Cite This Page

Bahls, L. (2016). Cymbella stigmaphora. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/cymbella_stigmaphora

Responses

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