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A Diatom - Stauroneis finlandia
General Description
Morphological Category – Symmetric biraphid
Valves lanceolate with gradually attenuated subrostrate apices. A prominent pseudoseptum is present at each apex.
Axial Area broad, about three times the width of the raphe, becoming somewhat wider near the central area.
Central Area a nearly rectangular stauros, only slightly wider at the valve margins.
Raphe fissures lateral, becoming reverse lateral and strongly curved near the large, proximal pores. Distal raphe fissures hooked towards the secondary side.
Striae radiate throughout.
Areolae coarse, 12-15 in 10 µm.
Size RangeLength 109-221 µm.
Width 24-34 µm.
Striae in 10 µm: 13-15.
Useful Link:
Diatom Glossary [Diatoms of North America website]
Diagnostic Characteristics
Stauroneis finlandia may be distinguished from
S. ursamaioris by its narrower, more attenuated apices and more widely spaced striae.
Stauroneis americana has broadly rounded apices and straight, weakly expanded proximal raphe ends.
Stauroneis kishinena lacks the subrostrate apices of
S. finlandia and has more widely spaced striae.
Stauroneis javanica, a fossil species from the Southern Hemisphere, has more weakly curved proximal raphe ends and narrower valves with unprotracted apices.
Range Comments
Northern Rocky Mountains.
Type Locality
Johns Fen, Glacier National Park, Montana.
Number of Observations in Montana Diatom Collection Database (Bahls 1968-2019): 6;
Montana: 6
Habitat
Mountain lakes and fens.
Ecology
Cold, circumneutral waters with low nutrients and conductivity (Bahls 2021).
Water Chemistry
Abundance-weighted mean values: pH = 7.0; conductivity = 34 µS/cm; water temperature = 6.3 degrees C.
Reproductive Characteristics
Diatoms typically reproduce by cell division (mitosis) and occasionally by meiosis—sexual reproduction in which female and male gametes combine to form a specialized zygote called an auxospore. Repeated divisions result in cells of a population becoming progressively smaller and smaller. When cells reach a critically small size, sexual reproduction is initiated, resulting in an auxospore and initial cells that are the largest attainable for the species, after which cell division and size reduction resume (Amato 2010).
Stewardship Responsibility
Threats or Limiting Factors
Stauroneis finlandia is a cold-water stenothermal diatom that has been rated as being of high risk of extinction due to climate change and regional warming (Bahls 2018).
References
- Literature Cited AboveLegend:
View Online Publication
Amato, A. 2010. Diatom reproductive biology: living in a crystal cage. The International Journal of Plant Reproductive Biology 2(1): 1-10.- Bahls, L. 2018. Potential loss of cold-water stenothermal diatoms (Bacillariophyta) from their southern refugia in the western United States. Diatom Research 32: 483-494.
- Bahls, Loren. 1968-Present. Montana Diatom Collection Database. Missoula, Montana.
- Bahls, Loren. 2021. Diatoms of Montana and Western North America: Catalog and Atlas of Species in the Montana Diatom Collection Volume 1. The Academy of Natural Sciences of Philadelphia Special Publication 24. 508pp.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Bahls, Loren. 2010. Stauroneis in the Northern Rockies: 50 species of Stauroneis sensu stricto from western Montana, northern Idaho, northeastern Washington and southwestern Alberta, including 16 species described as new. Northwest Diatoms, Volume 4. The Montana Diatom Collection, Helena, 172 pp.
- Hustedt, F. 1959. Die Kieselalgen Deutschlands, Osterreichs und der Schweiz, 2. Teil. In: Kryptogamen-Flora von Deutschlands, Osterreichs und der Schweiz, (Dr. L. Rabenhorst, ed.), Band VII(2). Reprint 1977, Otto Koeltz Science Publishers, Koenigstein, 845 pp.
- Krammer, K. and H. Lange-Bertalot. 1986. Bacillariophyceae. 1. Teil: Naviculaceae In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Süsswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.
- Lange-Bertalot, H. and Genkal, S.I. 1999. Diatoms from Siberia I. Islands in the Arctic Ocean (Yugorsky-Shar Strait). Iconographia Diatomologica 6:1-292.
- Molder, K. and R. Tynni. 1973. Uber Finnlands rezente und subfossile Diatomeen. VII. Bulletin of the Geological Society of Finland 45:159-179.
- Van de Vijver, B., Beyens, L. and Lange-Bertalot, H. 2004. The genus Stauroneis in Arctic and Antarctic Regions. Bibliotheca Diatomologica 50, 312 pp.
- Web Search Engines for Articles on "A Diatom"
