Halamphora thumensis | Species - Diatoms of North America

Category

Asymmetric Biraphid
Length Range

9-13 µm
Width Range

3.8-4.2 µm
Striae in 10 µm

22-25

Synonyms

Amphora thumensis (Mayer) Krieger 1929
Cymbella thumensis (Mayer) Hust. 1945

Contributor

Joshua Stepanek - Mar 2011
Reviewer

Sam Rushforth - Aug 2013

Identification

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Description

Valves are broadly semi-elliptical to semi-circular, with a smoothly arched dorsal margins and convex ventral margins. Valve ends are protracted and capitate. The raphe is located near the ventral margin, straight, with proximal ends straight to slightly dorsally deflected. The axial area is narrow at the poles, widening to form a lanceolate central area. A dorsal fascia is absent. A ventral fascia is present, extending to the ventral margin. Dorsal striae are composed of a single row of areolae, parallel near the central area becoming radiate towards the poles. Ventral striae are radiate near the central area, becoming slightly convergent near the poles.

The systematic position of Halamphora thumensis was under some debate. See Kingston et al. (1980), Krammer (1980) and Levkov (2009) for a thorough discussion.

Autecology

Reported in small abundances in oligotrophic lakes

Size Range, µm3

11-100
Motility

Moderately motile
Attachment

Prostrate
Habitat

Benthic
Colony

Solitary
Waterbody

Inland
Distribution

California coastal rivers 2017 Northeast lake sediments Great Lakes inventory
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Original Description

Basionym

Amphora coffeaeformis var. thumensis
Author

Mayer 1919

Original Images

Citations & Links

Citations

Cite This Page

Stepanek, J. (2011). Halamphora thumensis. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/46134/halamphora_thumensis

Responses

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