(Grunow ex Schmidt) Mann and Stickle in Round et al. 1990 Category: Symmetrical biraphid
BASIONYM: Navicula scutiformis Grunow ex Schmidt 1881
Contributor: Loren Bahls - October 2012
Length Range: 18-36 µm
Width Range: 12.3-17.7 µm
Striae in 10 µm: 24-26 at the valve center, 28-32 near the apices
Valves are elliptic with broadly rounded apices. The axial area widens gradually toward the valve center to a large, orbicular central area. The raphe is filiform with distinctly expanded proximal ends. Distal raphe fissures are small. Striae are radiate throughout and more broadly spaced near the valve center. Areolae nearest the central area are larger and transapically elongate. Areolae number 16-20 in 10 µm near the valve center, 20-24 in 10 µm near the apices.
Basionym: Navicula scutiformis
Author: Grunow ex Schmidt 1881
Length Range: µm
Striae in 10 µm:
Image provided by Schmidt (1881) without description.
Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 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.
Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
Schmidt, A. (-). (1874-1959). Atlas der Diatomaceen-Kunde, von Adolf Schmidt, continued by Martin Schmidt, Friedrich Fricke, Heinrich Heiden, Otto Muller, Friedrich Hustedt. Reprint 1984, Koeltz Scientific Books, Konigstein, 480 plates.
Cavinula scutiformis has been recorded from two lakes in northwestern Montana near the border with British Columbia. In one of these lakes (Upper Wolverine Lake, below), pH measured 8.83, specific conductance was 107 µS/cm, and temperature was 12.5 degrees C. Krammer and Lange-Bertalot (1986) report this species from electrolyte-poor waters in northern regions of Europe, Asia, and the Americas. Patrick and Reimer (1966) report C. scutiformis from the Middle Atlantic states and South Carolina. The type locality is Stavanger, Norway.
Upper Wolverine Lake, Ten Lakes Scenic Area, Kootenai National Forest, Lincoln County, Montana: home of Cavinula scutiformis.
Credit/Source: Loren Bahls