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Humidophila schmassmanni

(Hust.) Buczkó and Wojtal 2015      Category: Symmetrical biraphid
BASIONYM: Navicula schmassmanni Hust. 1943

Humidophila pantropica


Humidophila undulata

LM scalebar = 10 µm = 80 pixels.


Contributor: Megan Otu | Sarah Spaulding - March 2011
Length Range: 7-8 µm
Width Range: 2.4-4.0 µm
Striae in 10 µm: 30-43


Valves are linear elliptical with convex margins and capitate, rostrate or blunt apices. Specimens within a population may be irregular (asymmetrical) and are often variable in the shape of the apices. In general, the axial area is narrow near the apices, becoming more broad near the central area. The central area is lanceolate, with a thickened and distinct central nodule. The raphe is filiform and straight, with slightly expanded external proximal raphe ends. Internally, the helictoglossae are small and indistinct. The striae are parallel to slightly radiate in the central valve. The striae are variable in the center valve; some stria may be shorter or curved in the center of the valve. Striae are composed of a single, elongate areola on the valve face. A smaller areola is positioned on the valve mantle. Internally, the proximal raphe has short, deflected ends.

Original Description

Basionym: Navicula schmassmanni
Author: Hust. 1943
Length Range: 6-10 µm
Width Range: 2.5-3 µm
Striae in 10 µm: 24-30 in the center valve, 36-40 at the ends

Original Description

Navicula Schmassmanni Hust., in A.S. Atl., T. 400, F. 48 bis 52. Im Davoser Gebiet ziemlich verbreitet: Kleiner Flüelasee, Schwarzsee und in dessen Abfluss, oberer und unterer Grialetschsee. Wurde 1934 (l.c.) als neue Art aus diesem Material veröffentlicht:

Schalen im Umriss linear-elliptisch mit stark konvexen Rändern und breiten, kopfig abgeschnürten Enden, 6-10 µ lang, 2,5-3 µ breit. Raphe gerade, mit zeimlich entfernt gestellten Zentralporen. Axialarea und Zentralarea einen schmal lanzettlichen Raum einnehmend, ohne besonders abgesetzte Zentralarea. Transapikalstreifen durchweg leicht radial, im mittleren Teil der Schale 24-30 in 10 µ, gegen die Enden allmählich enger werdend, vor der Polen 36-40 in 10 µ. (Abb. 36, 37)

Original Images

Cite This Page:
Otu, M., and Spaulding, S. (2011). Humidophila schmassmanni. In Diatoms of the United States. Retrieved May 24, 2018, from

Species: Humidophila schmassmanni

Contributor: Megan Otu | Sarah Spaulding

Reviewer: Pat Kociolek


Buczkó, K., Wojtal, A.Z., Beszteri, B. and Magyari, E.K. (2015). Morphology and distribution of Navicula schmassmannii Hustedt and its transfer to genus Humidophila. Studia Bot. Hung. 46(1): 25-41. 10.17110/StudBot.2015.46.1.25

Hustedt, F. (1943). Die Diatomeenflora einiger Hochgebirgsseen der Landschaft Davos in den schweizer Alpen. Internationale Revue der gesamten Hydrobiologie und Hydrographie 43:124-197, 225-280.

Šporka, F., Štefkov, E., Bitušík, P., Thompson, A.R., Agustí-Panareda, A., Appleby, P.G., Grytnes, J.A., Kamenik, C., Krno, I., Lami, A., Rose, N. and Shilland, N.E. (2002). The paleolimnological analysis of sediments from high mountain lake Nizné Terianske pleso in the High Tatras (Slovakia). Journal of Paleolimnology 28: 95-109. 10.1023/A:1020376003123

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Humidophila schmassmanni 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

Humidophila schmassmanni

EMAP Response Plots

Humidophila schmassmanni

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.


December 8, 2016 - Transfer from Navicula to Humidophila

From March 2011 until December 2016, this taxon appeared on Diatoms of the United States as Navicula schmassmanni Hustedt 1943. Based on (Buczkó et al. 2015), this taxon updated to Humidophila schmassmanni (Hustedt) Buczkó et Wojtal 2015. - S. Spaulding