Stauroneis acuta
W.Sm. 1853 Category: Symmetrical biraphid
LM scalebar = 10 µm = 20 pixels.
Observations
Contributor: Loren Bahls - November 2011
Length Range: 121-175 µm
Width Range: 21-29 µm
Striae in 10 µm: 12-15
Description
Valves are rhombic-lanceolate and somewhat gibbous at the center, with acutely rounded apices. Pseudosepta are very prominent at the apices. The axial area is narrow near the valve apices, becoming much wider toward the central area. The central area is a wide stauros, expanding in deltoid fashion toward the valve margins. External raphe fissures are lateral, becoming filiform at the distal and proximal ends. Proximal raphe ends are weakly expanded and nearly straight. Striae are strongly radiate throughout and continue onto the valve mantle. Areolae are coarse, 12-15 in 10 µm. Cells are commonly found adherent face-to-face in short colonies. Elements of the cingulum and pseudosepta are evident in girdle view.
Original Description
Basionym:
Author: W.Sm. 1853
Length Range: µm
Striae in 10 µm:
Original Description
Original Images
Cite This Page:
Bahls, L. (2011). Stauroneis acuta. In Diatoms of the United States. Retrieved April 18, 2018, from http://westerndiatoms.colorado.edu/taxa/species/stauroneis_acuta
Species: Stauroneis acuta
Contributor: Loren Bahls
Reviewer: Sarah Spaulding
Image Credit: Loren Bahls
- Valves large, rhombic-lanceolate with a gibbous central region
- Pseudosepta present
- Proximal raphe ends straight, weakly expanded
- Stauros bow-tie shaped
- Striae strongly radiate
Stauroneis acuta has large rhombic-lanceolate valves with a gibbous central region, acutely rounded apices with pseudosepta, straight and weakly expanded proximal raphe ends, strongly radiate striae, and a large stauros shaped like a bow tie.
Compare
The rhombic-lanceolate valves, acutely rounded apices, and straight, weakly expanded proximal raphe ends make S. acuta distinctly different from most other large Stauroneis species with pseudosepta. Stauroneis terryi attains a much larger size and has a wider raphe and axial area.
Stauroneis terryi
D.B.Ward
Citations
Bahls, L. (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.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Smith, W. (1853). Synopsis of British Diatomaceae. John Van Voorst, London 1853. 89 pp., pls 1-31.
Van de Vijver, B., Beyens, L. and Lange-Bertalot, H. (2004). The genus Stauroneis in Arctic and Antarctic Regions. Bibliotheca Diatomologica 50, 312 pp.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
NCBI Genbank Taxonomy
North American Diatom Ecological Database (NADED)
NADED ID: 62036
Autecology Discussion
Stauroneis acuta is one of two Stauroneis species in the Northern Rockies with frustules commonly found adherent face-to-face in coloneis. The other colony-forming species is Stauroneis kishinena. Stauroneis acuta is widely distributed in small lakes in both the northern and southern hemispheres (Patrick & Reimer 1966, Van de Vijver et al. 2004) and appears to prefer slightly alkaline waters with low to moderate levels of dissolved solids. It is rarely found in large numbers.
Images
Lonesome Lake, Waterton Lakes National Park, Alberta, Canada: home of Stauroneis acuta.
Credit/Source: Barb Johnston, Parks Canada