Cymbella perfossilis | Species - Diatoms of North America

Category

Asymmetric Biraphid
Length Range

70-138 µm
Width Range

17.4-26.3 µm
Striae in 10 µm

8-11 at the valve center, up to 12 near the apices

Contributor

Loren Bahls - Jun 2016
Reviewer

Diane Winter - Jan 2017

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Identification

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Description

Valves are dorsiventral with a strongly arched dorsal margin. The ventral margin is weakly concave, with a slightly tumid center. Apices are broadly rounded, somewhat protracted in the smallest valves. The axial area is narrow. The central area is large and irregularly rounded. From 4-8 stigmata form a straight line on the ventral side of the central area, placed at some distance from the ends of the median ventral striae. In some specimens, there is an additional isolated stigma on the dorsal side of the central area. The raphe is lateral. Proximal raphe ends are hook-shaped and are deflected ventrally. Terminal raphe fissures are deflected dorsally at about 45 degrees. Striae are radiate throughout, more strongly radiate near the apices. Areolae are easily resolved in LM and number 16-20 in 10 µm.

Autecology

Cymbella perfossilis is a "living fossil". This species was described from fossil material collected near Terrebonne, Oregon, on the eastern slopes of the Cascade Mountains. Extant populations were recently found nearby in three Cascade Mountain streams. In one of these streams (Snow Creek, photo below), pH measured 7.63 and specific conductance measured 27 µS/cm.

Size Range, µm3

10001-100000
Motility

Slightly motile
Attachment

Vertical
Habitat

Benthic
Colony

Solitary
Waterbody

Inland
Learn more about this

Credit: Kirsten Gallo, Siuslaw National Forest

Snow Creek, Deschutes County, Oregon.

Original Description

Author

Krammer 2002
Length Range

48-121 µm
Width

20-26 µm
Striae in 10µm

7-11 at the valve center, up to 12 at the apices

Original Images

Citations & Links

Citations

Krammer, K. (2002) The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584

Cite This Page

Bahls, L. (2016). Cymbella perfossilis. In Diatoms of North America. Retrieved December 30, 2024, from https://diatoms.org/species/51464/cymbella_perfossilis

Responses

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