Achnanthes coarctata

(Brébisson ex W. Smith) Grunow in Cleve and Grunow 1880      Category: Monoraphid
BASIONYM: Achnanthidium coarctatum Brébisson ex W. Smith 1855

 

Achnanthes felinophila
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LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Rex Lowe | Sarah Spaulding - December 2011
Length Range: 32-70 µm
Width Range: 9.4-15 µm
Striae in 10 µm: 11 on the raphe valve, 9-10 on the rapheless valve

Description

Frustules are heterovalvar. The valve margins are biundulate. The valve apices are rostrate, to only slightly expanded. The raphe valve face is concave about the transapical axis. On the raphe valve, the axial area is centered on the apical axis and may be gently curved. The central area is a distinct transverse fascia, that may be asymmetric. The proximal raphe ends are straight and slightly expanded. The striae are distinct, uniseriate and punctate. The striae are nearly parallel near the central valve becoming radiate near the ends. The rapheless valve is convex about the transapical axis and lacks a fascia. The narrow sternum is eccentric and positioned on the margin, except at the widest points of the valve. The striae are distinct, uniseriate and punctate. The striae are nearly parallel near the central part of the valve becoming radiate and curved near the ends.

As a result of the concave and convex valve faces, the frustule of A. coarctata is recurved in girdle view, where the raphe valve valve fascia is on concave side of the frustule.

Original Description

Basionym: Achnanthidium coarctatum
Author: Brébisson ex W. Smith 1855
Length Range: µm
Striae in 10 µm:

Original Description

Achnanthidium coarctatum, Bréb.

Valve linear-elliptical, constricted at the centre, attenuate, and constricted towards the rounded extremities. Striæ moniligorm, 24 in ·001”. Length of frustule ·0013” to ·0018”. v.v. Bréb in Kütz. Sp. Alg. p. 54 ad specim. authen. quæ dedit am. De Brébisson.

Fresh water. Cave near Royat ; Grassmere, Westmoreland, Aug. 1853, W. Sm.

Original Images

Cite This Page:
Lowe, R., and Spaulding, S. (2011). Achnanthes coarctata. In Diatoms of the United States. Retrieved May 21, 2013, from http://westerndiatoms.colorado.edu/taxa/species/achnanthes_coarctata

Species: Achnanthes coarctata

Contributor: Rex Lowe | Sarah Spaulding

Reviewer: Marina Potapova

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Image Credit: Sarah Spaulding

  1. Valve margin biundulate
  2. Raphe valve with central fascia
  3. Areolae distinct
  4. Rapheless valve with eccentric axial area

Valves have biundulate margins, with a central constriction. The raphe valve face has a broad, central fascia. The fascia maybe asymmetric. The rapheless valve has a narrow, eccentric axial area. Striae are uniseriate and distinctly punctate.

Compare

Achnanthes coarctata has a central constriction, while A. inflata has a central inflation of the valve margin.

Achnanthes inflata

Citations

Boyle, J.A., Pickett-Heaps, J.D. and D.B. Czarnecki. (1984). Valve morphogenesis in the pennate diatom Achnanthes coarctata. Journal of Phycology 20(4): 563-573.

Cleve, P.T. and Grunow, A. (1880). Beiträge zur Kenntniss der Arctischen Diatomeen. Kongliga Svenska-Vetenskaps Akademiens Handlingar, Vol: 17, Issue: 2, 121 pp., 7 pls.

Geitler, L. (1980). Zellteilung und Bildung von Innenschalen bei Hantzschia amphioxys und Achnanthes coarctata. Plant Systematics and Evolution 136:275-286.

Links & ID's

Index Nominum Algarum (INA)

Original INA
Transfer INA

California Academy of Sciences (CAS)

Achnanthes coarctata CAS

North American Diatom Ecological Database (NADED)

NADED ID: 2041

Autecology Discussion

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

weakly motile (e.g. Actinella)

Attachment

vertical (e.g. stalks)

Habitat

moist habitats (moist soils, wet walls)

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

Achnanthes coarctata

Distribution

The distribution map represents the relative abundance of this Achnanthes coarctata 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 Achnanthes coarctata was not recorded, or with a red circle indicating the relative abundance of Achnanthes coarctata.

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

Achnanthes coarctata

Responses

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