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A Diatom - Stauroneis pikuni
Native Species
Global Rank:
GNR
State Rank:
SNR
(see State Rank Reason below)
Agency Status
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Stauroneis pikuni is a regional endemic found only in Montana, USA, and Alberta, Canada (Bahls 2021).
General Description
Morphological Category – Symmetric biraphid
Valves lanceolate to rhombic-lanceolate with narrow capitate apices.
Raphe branches moderately lateral, becoming filiform at the distal and proximal ends. Proximal raphe ends straight and not expanded.
Axial Area narrow and linear, barely wider than the raphe, expands slightly at the central area.
Central Area a rectangular stauros.
Striae radiate throughout.
Areolae round to transapically oblong, irregularly spaced, 20-24 in 10 µm.
Size RangeLength 53-64 µm.
Width 9.0-12.0 µm.
Striae in 10 µm 24-28.
Useful Link:
Diatom Glossary [Diatoms of North America website]
Diagnostic Characteristics
Stauroneis pikuni lacks the hyaline areas in the striae adjacent to the central area that are characteristic of
Stauroneis gracilior. It is also larger than
S. gracilior and has somewhat finer (more closely spaced) striae and areolae.
Stauroneis pikuni has larger and more gracile valves than
S. Kootenai.
Stauroneis neohyalina has linear-lanceolate valves and much finer striae and areolae.
Stauroneis schroederi has linear-lanceolate valves with very narrow rostrate to subcapitate apices.
Range Comments
Stauroneis pikuni is only known from Montana and Alberta (Bahls 2021).
Type Locality
Two Medicine Campground Pond, Glacier National Park.
Specimen housed at the University of Montana Herbarium (MONTU).
Global distribution
Rocky Mountains, East Greenland.
Number of Observations in Montana Diatom Collection Database (Bahls 1968-2019): 12;
Montana: 10
Habitat
Lakes, and in Montana ponds (Bahls 2021).
Ecology
Cold, circumneutral waters with low nutrients and conductivity (Bahls 2021). In waters where Stauroneis pikuni occurs, pH ranges from 6.6 to 7.3 and specific conductance ranges from 8 to 71 µS/cm. Van de Vijver et al. (2004) reported this taxon (as
Stauroneis gracilior "Zackenberg") from the Zackenberg area of East Greenland.
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
Climate change and regional warming.
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, 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. 2023. Diatoms of Montana and western North America: Catalog and atlas of species in the Montana diatom collection Volume 2. The Academy of Natural Sciences of Philadelphia Special Publication 27. 600pp.
- Web Search Engines for Articles on "A Diatom"
