(Ehrenberg) Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Navicula inaequalis Ehrenberg 1838
SYNONYM(S): Cymbella inaequalis (Ehrenberg) Rabenhorst
REPORTED AS: Cymbella inaequalis (Patrick and Reimer 1975, p. 36, plate 5, fig. 3)
Valves are rhomboid-lanceolate and moderately dorsiventral, with strongly arched dorsal and ventral margins. Apices are bluntly rounded and subrostrate to rostrate. The axial area follows close to the valve midline. The axial area is sub-linear, narrowest near the apices and widening gradually toward the valve middle where it merges with a somewhat wider elliptical central area. The central area is about one-quarter the width of the valve. The raphe is lateral and narrows near the proximal and distal ends. Proximal raphe ends are straight and terminated in expanded pores. Distal raphe fissures are curved, concave toward the dorsal margin. Striae are coarsely punctate and radiate, becoming parallel only very near the apices. Striae tend to be curved toward the valve center. Areolae number 14-22 in 10 µm.
Basionym: Navicula inaequalis
Author: Ehrenberg 1838
Length Range: µm
Striae in 10 µm:
Ehrenberg, C.G. (1838). Die Infusionsthierchen als vollkommene Organismen. Ein Blick in das tiefere organische Leben de Natur. erlag von Leopold Voss, Leipzig. pp. 1-xvii, 1-548, pls. 1-64.
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Cymbopleura inaequalis is widely distributed in lakes, ponds, and slow-moving streams across the United States, where it prefers somewhat alkaline waters of moderate conductivity (Patrick and Reimer 1975, Montana Diatom Database). This species has a wider ecological amplitude than most species of Cymbopleura. Because of its large size, this taxon is often overlooked during proportional counts along predetermined transects. It is probably much more widely distributed than records suggest.
Lake McDonald, Glacier National Park, Montana: home of Cymbopleura inaequalis.
Credit/Source: National Park Service Webcam Photo