Lange-Bertalot and Krammer in Lange-Bertalot and Genkal 1999 Category: Asymmetrical biraphid
BASIONYM: Cymbopleura heinii Lange-Bertalot and Krammer in Lange-Bertalot and Genkal 1999
REPORTED AS: Cymbella acutiuscula (Hein 1990, p. 31, plate 8, fig. 1)
Contributor: Loren Bahls - August 2012
Length Range: 100-207 µm
Width Range: 27-39 µm
Striae in 10 µm: 8-10 at the valve center, 14-16 at the apices
Valves are broadly elliptic-lanceolate and slightly to moderately dorsiventral in large and small specimens, respectively. The arched dorsal and ventral margins taper to broadly rostrate apices. The axial area is wide and expands gradually along the valve midline from the apices toward a somewhat wider, rounded central area. The axial and central area are sometimes ornamented with faint spots that are about the same size as areolae, but irregularly arranged. The raphe is distinctly lateral and becomes reverse-lateral near the proximal and distal ends. Proximal raphe ends with small ventrally deflected “crochet hooks” (Figs 5 and 6 above), but in most specimens the ends appear to be simply expanded. Distal raphe fissures are comma-shaped and deflected dorsally. Striae are radiate throughout and distinctly punctate. Areolae are coarse and number 16-18 in 10 µm.
Basionym: Cymbopleura heinii
Author: Lange-Bertalot and Krammer in Lange-Bertalot and Genkal 1999
Length Range: 115-137 µm
Width Range: 30-32 µm
Striae in 10 µm: 8-9 at the valve center, 12-13 near the ends
Valves slightly dorsiventral, broadly elliptical-lanceolate, dorsal and ventral margins arched, tapering abruptly to moderately wide rostrate ends. Length 115-137 µm, breadth 30-32 µm, maximum length/breadth ratio 3.6. Axial area moderately wide, almost in the median line of the valve, broadening gradually towards valve centre to form a not distinctly set off elliptical central area, 1/3 the valve breadth, asymmetrical and more well developed dorsally. Raphe distinctly lateral, narrowing towards the distal ends, appearing strongly reverse-lateral near the proximal ends. Proximal raphe ends crochet-hooked and ventrally tipped, terminal fissures comma-shaped and dorsally deflected. Striae radiate throughout, distinctly punctate. Striae in the middle portion (dorsal) 8-9/10 µm, 12-13/10 µm towards the ends, puncta 15-17/10 µm.
Hein, M. (1990). Flora of Adak Island, Alaska: Bacillariophyceae (Diatoms). Bibliotheca Diatomologica (H. Lange-Bertalot, ed.), Band 21, J. Cramer, Berlin, 133 pp.+ 53 plates.
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 Genkal, S.I. (1999). Diatoms from Siberia I. Islands in the Arctic Ocean (Yugorsky-Shar Strait). Iconographia Diatomologica 6: 1-292.
Cymbopleura heinii has been recorded from 13 lakes, ponds and fens in the northern Rocky Mountains of western Montana. The population described here is from Johns Fen in Glacier National Park, where it is abundant. Here pH measured 6.02 and specific conductance measured 58 µS/cm. Hein (1990) reported this species (as Cymbella acutiuscula) from Adak Island, Alaska.
Red Eagle Pond, Glacier National Park, Montana: home of Cymbopleura heinii.
Credit/Source: E. William Schweiger, National Park Service