Cymbella
Agardh 1830 Category: Asymmetrical biraphid
TYPE SPECIES: Cymbella cymbiformis Agardh
CLASS: Bacillariophyceae
ORDER: Cymbellales
FAMILY: Cymbellaceae
- Valves slightly to strongly asymmetric to the apical axis
- Valves symmetric to the transapical axis
- Distal raphe ends deflected dorsally
- Stigmata, if present, located on the ventral side
The valves of Cymbella are slightly to strongly dorsiventral, or asymmetric to the apical axis. Valves are symmetric to the transapical axis. The terminal raphe fissures are deflected to the dorsal side, an important diagnostic feature. Apical pore fields are present at both poles. Striae are uniseriate. One or more stigmata may be present. If a stigma or stigmata are present, they are located on the ventral side of the central area. Internally, the stigmata are convoluted internal occlusions. Also internally, the proximal raphe may be continuous across central area. Cymbella cells grow predominately in benthic habitats, and often produce mucilaginous stalks that are secreted through the apical porefield.
Historically, Cymbella has been a large, heterogenous group and is not considered to be a natural, or monophyletic group of species. Recently, a number of genera have been split from Cymbella, including Cymbopleura, Delicata and Encyonopsis.
Cite This Page:
Spaulding, S., and Edlund, M. (2008). Cymbella. In Diatoms of the United States. Retrieved June 20, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Cymbella
Contributor: Sarah Spaulding | Mark Edlund - December 2008
Citations
Kermarrec, L., Ector, L., Bouchez, A., Rimet, F. and Hoffmann, L. (2011). A preliminary phylogenetic analysis of the Cymbellales based on 18S rDNA gene sequencing. Diatom Research 26(3). 10.1080/0269249X.2011.633255
Krammer, K. (1982). Valve morphology and taxonomy in the genus Cymbella C.A. Agardh. Morphology of Diatom Valves 11: 1-299.
Krammer, K. (1997). Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema part., Encyonopsis and Cymbellopsis. Bibliotheca Diatomologica 37:1-469.
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
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. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.