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Achnanthes subhudsonis var. kraeuselii

(Cholnoky) Cholnoky 1956      Category: Monoraphid
BASIONYM: Achnanthes kraeuselii Cholnoky 1954

REPORTED AS: Achnanthes subhudsonis (Hustedt 1921, p. 144; fig. 9-12 ) | Achnanthidium subhudsonis (Kobayasi et al. 2006, p. 13, 129 ) 

Achnanthes rostellata


Achnanthes tumescens

LM scalebar = 10 µm = 80 pixels.


Contributor: Sarah Spaulding | Marina Potapova - December 2014
Length Range: 9-14 µm
Width Range: 2.9-4.0 µm
Striae in 10 µm: 20


Valves are narrow and lanceolate. The raphe valve has a lanceolate axial area becoming narrow at the apices. The raphe is expanded near the valve center and the external proximal raphe ends have expanded pores. Internally, the proximal raphe ends are slighly deflected to the opposite side from the terminal fissures. The terminal raphe fissures are deflected to the same side and extend over the valve mantle. Striae are radiate and more broadly spaced at the central valve than near the ends. The rapheless valve is flexed about the apical axis. The rapheless valve also has a more narrow lanceolate axial area than the raphe valve. The axial area of the rapheless valve is asymmetrically bent near the apices in many specimens. Striae are slightly radiate on the rapheless valve. The striae are composed of poroid areolae. The external and internal openings of the areolae are circular, or nearly so.

Note that Hustedt (1921) described the species, A. subhudsonis from tropical regions. This taxon is reported as having a higher stria density and parallel striae (as compared to radiate striae)(Simonsen 1987) than the specimens illustrated here. Cholnoky (1954) described A. kraeuselli and later included it as a variety, A. subhudsonis var. kraeuselii, the name we adopt here. We expect that future work with resolve the differences, if there are differences, between the nominate and other varieties. We also expect that this taxon will soon be included in a new genus; it is clearly not aligned with either Achnanthes as it was originally described (Cholnoky 1954), or Achnanthidium as it was later transferred (Kobayashi et al. 2006).

Original Description

Basionym: Achnanthes kraeuselii
Author: Cholnoky 1954
Length Range: 12-25 µm
Width Range: 4-6 µm
Striae in 10 µm: 16-18

Original Description

Original Images

Cite This Page:
Spaulding, S., and Potapova, M. (2014). Achnanthes subhudsonis. In Diatoms of the United States. Retrieved May 20, 2018, from

Species: Achnanthes subhudsonis

Contributor: Sarah Spaulding | Marina Potapova

Reviewer: Pat Kociolek


Cholnoky, B.J. (1954). Diatomeen und einige andere Algen aus dem “de Hoek”. Reservat in Nord-Transvaal. Botaniska Notiser 3: 269-296.

Cholnoky, B.J. (1956). Neue und seltene Diatomeen aus Afrika. II. Diatomeen aus dem Tugela-Gebiete in Natal. Österreichische Botanische Zeitschrift 103: 53-97.

Hofmann, G., Werum, M. and Lange-Bertalot, H. (2011). Diatomeen im Süßwasser-Benthos von Mitteleuropa. Koeltz Scientific Books, Königstein, 908 pp.

Hustedt, F. (1921). Bacillariales. In: (B. Schröder, ed.) Zellpflanzen Ostafrikas, gesammelt auf der Akademischen Studienfahrt 1910. Hedwigia 63: 117-173.

Kobayasi, H., Idei, M., Mayama, S., Nagumo, T. and Osada, K. (2006). H. Kobayasi’s Atlas of Japanese Diatoms based on electron microscopy. Volume 1. Uchida Rokakuko Publishing Co., Tokyo. 59 + 533 pp., 180 pls.

Simonsen, R. (1987). Atlas and Catalogue of the Diatom Types of Friedrich Hustedt. J. Cramer, Berlin & Stuttgart 1: 525 pp.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Achnanthes subhudsonis var. kraeuselii CAS

North American Diatom Ecological Database (NADED)

NADED ID: 2132

Autecology Discussion

Achnanthes subhudsonis var. kraeuselii was described from moss and aerophilic habitats in South Africa (Cholnoky 1954). This tropical species is considered to be an invasive species to Europe (Hofmann et al. 2011). It is not clear if it is also a new arrival to North America.

EMAP Assessment

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). Over 1200 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 subhudsonis var. kraeuselii

EMAP Response Plots

Achnanthes subhudsonis var. kraeuselii

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.