Rossithidium petersenii

(Hustedt) Aboal in Aboal, Alvarez-Cobelas, Cambra and Ector 2003      Category: Monoraphid
BASIONYM: Achnanthes petersenii Hustedt 1937

Rossithidium nodosum

 

Rossithidium pusillum
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Marina Potapova - May 2010
Length Range: 13-18.5 µm
Width Range: 3.5-4.5 µm
Striae in 10 µm: 32-36

Description

Valves are linear or linear-elliptical with rounded ends. The raphe valve has a narrow axial area and a large rectangular or transversely elliptical central area that almost reaches the valve margins. The raphe is straight, filiform, and lacks terminal fissures. Internally, the central raphe endings are curved to opposite sides. The rapheless valve has a narrowly rhomboid axial area and no distinct central area. Striae are uniseriate and slightly radiate. Each stria in the middle part of the valve contains 5-7 areolae. The valve mantle bears one row of areolae.

Original Description

Basionym: Achnanthes petersenii
Author: Hustedt 1937
Length Range: 12-17 µm
Width Range: 3.5-4 µm
Striae in 10 µm: 36 in the middle, about 40 at the poles

Original Description

Zellen mit schwach verkieselten Membranen, sehr hyalin. Schalen linear-elliptish, gegen die breit gerundeten Enden etwas verschmälert, 12-17 µ lang, 3,5-4 µ breit. Raphenschale mit gerader, fadenförmiger Raphe, Axialarea sehr eng, Zentralarea eine breite, bisanden Schalenrand reichende Querbinde. Transpikalstreifen im mittleren Teil etwa 36 in 10 µ, gegen die Pole enger werdend, bis etwa 40 in 10 µ, durchweg leicht radia. Raphenlose Schale mit schmal linearer, zuweilen in der Mitte etwas erweiterer Pseudoraphe, Transapikalstreifen etwas gröber, im mittleren Teil etwa 30 in 10 µ, gegen Enden ebenfalls enger werdend, durchweg radial. Fig. 10-14.

Original Images

Cite This Page:
Potapova, M. (2010). Rossithidium petersenii. In Diatoms of the United States. Retrieved May 25, 2013, from http://westerndiatoms.colorado.edu/taxa/species/rossithidium_petersenii

Species: Rossithidium petersenii

Contributor: Marina Potapova

Reviewer: Sam Rushforth

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Image Credit: Marina Potapova

  1. Valve linear to linear-elliptical
  2. Raphe straight
  3. Striae unseriate
  4. Raphe valve with a large rectangular or transverse elliptical central area
  5. Rapheless valve with a narrowly rhomboid axial area

Valves are linear or linear-elliptical with rounded ends, 3.5-4.5 µm wide, 13-18.5 µm long. Raphe valve has a large transverse elliptical central area that almost reaches the valve margins. Terminal raphe fissures are absent. Rapheless valve has a narrowly rhomboid axial area and no distinct central area. Striae are uniseriate, slightly radiate, and number 32-36 in 10 µm.

Compare

Rossithidium petersenii differs from R. pusillum by having larger valves, a higher stria density, and a large rectangular or elliptical central area on the raphe valve and a narrowly rhomboid axial area on the rapheless valve. Rossithidium petersenii can be confused with frequently co-occurring Achnanthidium kranzii, that also has a large central area on the raphe valve, but can be distinguished from A. kranzii by wider and more linear valves, the narrowly rhomboid axial area on the rapheless valve, and the absence of terminal raphe fissures.

Achnanthidium kranzii

Rossithidium pusillum

Citations

Aboal, M., Alvarez-Cobelas, M., Cambra, J. and Ector, L. (2003). Floristic list of non marine diatoms (Bacillariophyceae) of Iberian Peninsula, Balearic Islands, and Canary Islands. Updated taxonomy and bibliography. In: A. Witkowski (ed.), Diatom Monographs. A.R.G. Gantner Verlag K.G., 4: 639 pp.

Hustedt, F. (1937). Sußwasserdiatomeen von Island, Spitzbergen und den Färöer-Inseln. Botanisches Archiv 38:152-207.

Links & ID's

Index Nominum Algarum (INA)

Original INA
Transfer INA

California Academy of Sciences (CAS)

Rossithidium petersenii CAS

North American Diatom Ecological Database (NADED)

NADED ID: 18900

Autecology Discussion

Habits

Size Range

11-100 µm3 (ie Achnanthidium)
101-1000 µm3 (ie Amphora veneta)

Motility

slightly motile (e.g. Cocconeis)

Attachment

prostrate (e.g. mucilage pad)

Habitat

benthic

Colony

solitary

EMAP Assessment

Sampling for the Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Rossithidium petersenii

Distribution

The distribution map represents the relative abundance of this Rossithidium petersenii in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Rossithidium petersenii was not recorded, or with a red circle indicating the relative abundance of Rossithidium petersenii.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

Rossithidium petersenii

Responses

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

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.