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Diatoms of the United States is now known as Diatoms of North America.
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Rapheless valve

Raphe ledge



The valve of a monoraphid pennate diatom lacking a raphe.

Alternative Term

pseudoraphe valve

The term pseudoraphe is used in much of the literature, including in Patrick and Reimer (1966).


The abbreviation for pseudoraphe valve, PRV, is used by Kingston in Wehr and Sheath (2003).

central sternum

The pseudoraphe is called the "central sternum" by some authors.


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.

Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

Wehr, J. and Sheath, R.G. (2003). Freshwater Algae of North America: Ecology and Classification. Academic Press, 917 pp.