Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Cymbopleura apiculata Krammer 2003
REPORTED AS: Cymbella cuspidata (Patrick and Reimer 1975, plate 6, fig. 2)
Contributor: Loren Bahls - August 2012
Length Range: 70-86 µm
Width Range: 24-28 µm
Striae in 10 µm: 8-10 (dorsal) and 9-11 (ventral) at the valve center; 13-15 (dorsal) and 14-16 (ventral) at the apices
Valves are broadly elliptic and slightly dorsiventral, with strongly arched dorsal and ventral margins. The ventral margin tapers toward short and somewhat ventrally deflected apiculate apices. The length to width ratio is 2.9-3.3. The narrow axial area widens gradually from the apices toward a large, rounded and asymmetric central area. The raphe is lateral and narrows toward the distal and proximal ends. Proximal raphe ends are deflected ventrally and shaped like a crochet hook or a crosier. Terminal raphe fissures are deflected dorsally. Striae are radiate throughout and more closely spaced towards the apices. Areolae are easily resolved in LM and number 18-24 in 10 µm.
Basionym: Cymbopleura apiculata
Author: Krammer 2003
Length Range: 45-113 µm
Width Range: 22-27 µm
Striae in 10 µm: 8-10 at valve center (dorsal); 12-15 towards the apices
Valves not or only very slightly dorsiventral, broadly subelliptical to elliptical-lanceolate, dorsal and ventral margins strongly arched, tapering abruptly to apiculate-cuspidate ends. Length 45-113 µm, breadth 22-27 µm, maximum length/breadth ratio 3.5. Axial area moderately narrow, almost in the median line of the valve. Central area distinctly set off, about 1/3 the valve breadth, roundish or slightly elliptical, sometimes asymmetrical. Raphe lateral, narrowing towards the distal and proximal ends. Proximal raphe ends slightly ventrally tipped (Fig. 7:8) or crochet-hooked (Fig. 11:1); terminal fissures dorsally deflected (Fig. 7:9). Striae radiate throughout, distinctly punctate (Fig. 7:8, 10). Striae in the middle portion (dorsal) 8-10/10 µm, 12-15/10 µm towards the ends, puncta 18-23/10 µm.
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Cymbopleura apiculata has been recorded infrequently in small ponds and fens in the Northern Rockies, where it is associated with organic substrates and abundant aquatic vegetation. In one of these habitats (Cut Bank Pond, Glacier National Park), pH measured 7.77 and specific conductance measured 53 µS/cm. In another (Skinner Pond #1, Beaverhead County, Montana), pH measured 7.82 and specific conductance measured 49 µS/cm.
Akokala Fen, Glacier National Park, Montana: home of Cymbopleura apiculata.
Credit/Source: E. William Schweiger, National Park Service.
Sofa Mountain Wetland A, Waterton Lakes National Park, Alberta: home of Cymbopleura apiculata.
Credit/Source: Barb Johnston, Parks Canada.