Krammer 2002 Category: Asymmetrical biraphid
REPORTED AS: Cymbella cistula (Patrick and Reimer 1966)
Contributor: Carrie White - June 2011
Length Range: 32-85 µm
Width Range: 11-22 µm
Striae in 10 µm: 7-10 at valve center, 10-13 near ends
Valves strongly dorsiventral. The dorsal margin is convex and the ventral margin is linear to slightly curved and tumid at mid-valve. The valve ends are rounded, but not protracted or capitate. Striae are slightly radiate, distinctly punctate, with 16-22 areolae in 10 µm. The axial area is narrow, expanding slightly into a small round central area at mid valve. The raphe is centrally located within the axial area. The raphe is reverse lateral; the proximal raphe ends are bent ventrally and slightly expanded. Stigmata are present present on the ventral side of the central area. The number of stigmata is commonly 3-5, but occasionally only 2 stigmata are present. In some specimens, 1-2 stigmata or stigmata-like structures may be present on the dorsal side of the central area, particularly in initial cells.
Cymbella cistula was separated into three new taxa by Krammer (2002, p. 89-91). Krammer investigated 66 populations of C. cistula and morphologically similar diatoms and separated them into three taxa that could be readily distinguished from one another by number of stigmata, areola density, and overall valve outline: C. subcistula, C. neocistula, and C. dorsenotata.
Author: Krammer 2002
Length Range: 34-110 µm
Width Range: 12-19 µm
Striae in 10 µm: 7-9 in the center of valve, becoming 12 at the ends, punctae 17-20(22)
Valves doriventrales, cymbiformes, margine dorsali magis convexa, margine ventrali leviter concave vel plus minusve recta cum levi inflation in medio, apicibus non protractis et late rotundatis, 34-110 µm longae, 12-19 µm latae. Area axialis angusta, area centralis orbicularis, circiter ½-1/4 latitudinis valvae. Raphe modice lateralis, ad aream centralem modice reverso-lateralis ad apices sensim filiformis. Latere ventrali cum 3-5 stigmata. Striae transapicales modice radiatae, distincte punctatae, 7-9 in 10 µm, ad apices 12 in µm, punctae 17-20 (22) in 10 µm. A C. cymbiformis satis differ. Typus: Germania occidentalis, Eifel, lacus Holzmaar, 4.4.1977, praep. 255 IOK
Fukushima, H., Ko-bayashi T. and Ohtsuka, H. (1989). Morphological variation on Cymbella cistula (Ehr.) Kirchner. Japanese Journal of Water Treatment Biology 25: 31-38.
Hufford, T.L. and Collins, G.B. (1972). Some morphological variations in the diatom Cymbella cistula. Journal of Phycology 8: 192-195.
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
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.