(Fontell) Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Cymbella incerta var. linearis Fontell 1917
REPORTED AS: Cymbella angustata var. linearis (Ross 1947, p. 216)
Contributor: Loren Bahls - January 2014
Length Range: 41.8-55.5 µm
Width Range: 6.5-8.9 µm
Striae in 10 µm: 15-17 at the valve center, 20-24 at the ends on the dorsal side
Valves are linear and barely slightly dorsiventral, with nearly flat, parallel sides. The ventral side may be weakly concave. Apices are subrostrate to cuneate. The axial area is narrow but and widens slightly near the central area. The central area is rounded, about half as wide as the valve, and formed by shallow depressions on the dorsal and ventral sides. The raphe is lateral, becoming filiform near the ends. Proximal raphe ends are unexpanded and deflected ventrally. Distal raphe ends are hooked towards the dorsal side. Striae are radiate throughout and more widely spaced around the central area. Areolae in the striae are difficult to resolve in LM and number 28-34 in 10 µm.
Basionym: Cymbella incerta var. linearis
Author: Fontell 1917
Length Range: µm
Striae in 10 µm:
Fontell, C.W. (1917). Süsswasserdiatomeen Ober-Jämtland in Schweden. Arkiv för Botanik 14(21): 1-68.
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Ross, R. (1947). Fresh water Diatomeae (Bacillariophyta). In: Botany of the Canadian Eastern Arctic II. (N.V. Polunin, ed.). National Museum of Canada Bulletin 97:178-233, 3 pl.
This taxon was originally described from material collected in Sweden. The specimens shown here were collected from an oxbow of the Swan River in northwest Montana and from Lower Pond No. 1 at the Mexican Cut Nature Preserve in Colorado. The pH of the pond at Mexican Cut measured 6.88 and specific conductance measured 28 µS/cm.
Mexican Cut Nature Preserve, Gunnison County, Colorado. One of the many ponds at Mexican Cut supports a population of Cymbopleura incertiformis var. linearis.
Credit/Source: The Nature Conservancy