Van de Vijver and Lange-Bertalot 2004 Category: Symmetrical biraphid
BASIONYM: Stauroneis supergracilis Van de Vijver and Lange-Bertalot 2004
REPORTED AS: Stauroneis phoenicenteron f. gracilis (Patrick and Reimer 1966) | Stauroneis phoenicenteron f. gracilis (Camburn and Charles 2000) | Stauroneis regina (Bahls 2010)
Contributor: Loren Bahls - May 2012
Length Range: 124-213 µm
Width Range: 21-33 µm
Striae in 10 µm: 15-16
Valves are narrowly lanceolate with subtly protracted apices. The axial area is linear and two to three times wider than the raphe. The stauros is rectangular, often widening slightly near the valve margins. Short striae are absent from the stauros. The raphe is lateral with curved and inflated proximal ends. Terminal raphe fissures are hooked toward the secondary side. Striae are radiate throughout. Areolae are relatively coarse and number 14-18 in 10 µm.
Basionym: Stauroneis supergracilis
Author: Van de Vijver and Lange-Bertalot 2004
Length Range: 120-140 µm
Width Range: 20-22 µm
Striae in 10 µm: 16-17
Differential diagnosis compared to Stauroneis gracilis Ehrenberg: Valves relatively narrow-lanceolate with hardly protracted, simply bluntly rounded ends, valves gradually attenuating towards the ends (and not linear- or elliptic-lanceolate with protracted, subrostrate ends). Length 120-140 µm, breadth 20-22 µm (and not 75-120 µm and 15-20 µm). Raphe distinctly lateral with central external endings significantly curved with moderately deflected pores towards the secondary side of the valve (as in St. gracilis). Axial area almost linear and moderately broad, hardly widened near the central area. Central area forming a somewhat irregular fascia as to breadth, moderately widened towards the margins. Striae strongly radiate throughout, 16-17 in 10 µm. Puncta in the striae not very densely spaced, 17-18 (and not 18-21) in 10 µm. In the central area, sometimes (a few) irregularly shortened striae are present.
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.
Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 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.
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 supergracilis is widely distributed in lakes, ponds, and wetlands in the Northern Rockies. The pH of these waters ranges from 5.5 to 8.6 (mean pH = 6.7) and specific conductance ranges from 7 to 168 µS/cm (mean SC = 63 µS/cm). Van de Vijver et al. (2004) report this species from the sub-Antarctic, where it was found in a large shallow pool with slightly acid pH (6.6) and low specific conductance (<100 µS/cm).
Bloody Dick Pond No. 2, Beaverhead County, Montana: home of Stauroneis supergracilis.
Credit/Source: Loren Bahls