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Nupela lapidosa

(Krasske) Lange-Bert. 1999      Category: Symmetrical biraphid
BASIONYM: Achnanthes lapidosa Krasske 1929

REPORTED AS: Achnanthes  subrostrata var. appalachiana (Potapova 2011, pg. 76, Figs 28-39 ) 

Nupela impexiformis


Nupela neglecta

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - August 2010
Length Range: 10-28 µm
Width Range: 3.6-6.6 µm
Striae in 10 µm: 20-24


Valves are lanceolate to linear-lanceolate with slightly drawn-out ends. Raphe is absent on one valve. The rapheless valve has narrowly rhomboid axial area, which sometimes widens in the middle portion of the valve to form asymmetrical central area. The axial area of the rapheless valve has siliceous thickenings and depressions. The raphe valve has narrowly lanceolate axial area and circular or elliptical, often asymmetrically expanded central area. The raphe has a slightly curved external and straight internal slit. The proximal raphe ends are slightly expanded externally. Internally, the proximal raphe ends are bifurcated and turned sharply backwards. Striae are radiate through both valves, 20-24 in 10 μm. The external openings of the areolae are covered by the kidney-shaped hymens.

Note that examination of the holotype of Achnanthes subrostrata var. appalachiana Camburn and Lowe show diatoms that correspond to N. lapidosa (Potapova 2011). Consequently, A. subrostrata var. appalachiana is considered to be conspecific with N. lapidosa.

Original Description

Basionym: Achnanthes lapidosa
Author: Krasske 1929
Length Range: 20-24 µm
Width Range: 6-7 µm
Striae in 10 µm: 16 in 10 μm in upper valve, 18 in 10 μm in lower valve, 20 in 10 μm towards the ends

Original Description

Lanzettlich, Enden leicht vorgezogen. Die Langsarea beider Schalen erweitert sich lanzettlich nach der Mitte, um hier eine rundliche Zentralarea zu bilden, die auf der Oberschale, bei manchen Exemplaren auch auf der Unterschale einseitig durch das Fehlen der Mittelstreifen bis an den Rand erweitert ist. Streifen strahlend, 16 in 10 μ auf der Oberschale, 18 in 10 μ auf der Unterschale; auf dieser nach den Enden enger werdend, hier 20 in 10 μ. Lang 20-24 μ, breit 6-7 μ.

Original Images

Cite This Page:
Potapova, M. (2010). Nupela lapidosa. In Diatoms of the United States. Retrieved May 26, 2018, from

Species: Nupela lapidosa

Contributor: Marina Potapova

Reviewer: Sarah Spaulding


Krasske, G. (1929). Beiträge zur Kenntnis der Diatomeenflora Sachsens. Botanisches Archiv 27(3/4): 348-380.

Lange-Bertalot, H. (1999). Neue Kombinationen von taxa aus Achnanthes Bory (sensu lato). Iconographia Diatomologica 6: 276-289.

Potapova, M. (2011). New species and combinations in the genus Nupela from the USA. Diatom Research. 10.1080/0269249X.2011.575111

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

Nupela lapidosa CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

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

Nupela lapidosa

EMAP Response Plots

Nupela lapidosa

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.