W. Smith 1853 Category: Symmetrical biraphid
BASIONYM: Stauroneis acuta W. Smith 1853
Contributor: Loren Bahls - November 2011
Length Range: 121-175 µm
Width Range: 21-29 µm
Striae in 10 µm: 12-15
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.
Basionym: Stauroneis acuta
Author: W. Smith 1853
Length Range: µm
Striae in 10 µm:
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.
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.
Lonesome Lake, Waterton Lakes National Park, Alberta, Canada: home of Stauroneis acuta.
Credit/Source: Barb Johnston, Parks Canada