Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Cymbopleura metzeltinii Krammer 2003
REPORTED AS: Cymbella incerta (Lange-Bertalot & Mezeltin 1996, plate 61, figs 9-11; plate 95, fig. 15) | Cymbella incerta (?var.) (Lange-Bertalot and Metzeltin 1996, plate 95, figs 16, 17)
Contributor: Loren Bahls - August 2012
Length Range: 30-61 µm
Width Range: 7.6-10.3 µm
Striae in 10 µm: 15-17 at the valve center, 18-21 at the ends
Valves are rhomboid-lanceolate and barely dorsiventral, with both margins tapering to subtly protracted apices. The axial area follows nearly the median line of the valve and widens gradually from the apices to the valve center. The axial area is moderately wide and merges smoothly with a small rounded central area. The raphe is lateral and becomes filiform at the proximal and distal ends. The proximal raphe ends are ventrally displaced and terminate with small hooks on the ventral side. Distal raphe ends are shaped like question marks and deflected dorsally. Striae are indistinctly punctate and slightly radiate at the valve center to strongly radiate near the apices. Areolae number 28-34 in 10 µm.
Basionym: Cymbopleura metzeltinii
Author: Krammer 2003
Length Range: 32-67 µm
Width Range: 8.0-10.7 µm
Striae in 10 µm: 15-16 at the valve center, up to 19 towards the ends
Valves barely dorsiventral, rhomboid-lanceolate, dorsal and ventral margins tapering continuously to slightly rostrate to apiculate protracted ends. Length 32-67 µm, breadth 8-10.7 µm, maximum length/breadth ratio up to 7. Axial area narrow to moderately wide, almost in the median line of the valve, in larger specimens becoming narrower towards the ends. Central area in the smallest specimens nearly absent, in medium-sized specimens a small, distinctly roundish to elliptical depression on both sides, in post initial cells large (Fig. 115:8). Raphe in the nominate variety distinctly lateral, in var. julma narrowly lateral, narrowing towards the proximal and distal ends, in the middle ventrally displaced. Proximal raphe ends slightly expanded and somewhat ventrally tipped; terminal fissures ?-shaped and dorsally deflected. Striae slightly radiate throughout, indistinctly punctate. Striae in the middle portion (dorsal) 15-16/10 µm, up to 19/10 µm towards the ends, puncta 27-32/10 µm.
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.
NADED ID: 47250
Cymbopleura metzeltinii has been recorded in eight ponds and small lakes in Glacier National Park, Montana. Here pH ranges from 6.73 to 7.78 and specific conductance ranges from 22 to 71 µS/cm. It has also been recorded from Nada Lake, a small lake in Chelan County, Washington (photo below). This species was described from a lake (Mittersee) in the Austrian Tyrol and also reported from a lake in Finland (Julma Ölkky).
Cut Bank Pond, Glacier National Park, Montana: home of Cymbopleura metzeltinii.
Credit/Source: Loren Bahls
Nada Lake, Chelan County, Washington: home of Cymbopleura metzeltinii.
Credit/Source: Ryan Davis