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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Cosmarium phaseolus

b> Range & Status

This potential Red List desmid is an Endangered IUCN (1994), Nationally Rare species, and has been recorded at Lower Bostraze bog, near St. Just in West Penwith (SW392321). This area consists of a series of pools formed by old extraction pits filling with water from the surrounding moorland and has been identified as the most important desmid site on the south-west peninsula of Britain. This site, and many others, were sampled by John Ralfs, one of the most influential desmid specialists of his time in the middle part of the 19th century. More recently, in 1983 and 1993, it has been re-surveyed by David Williamson. The Lower Bostraze site is nominated as a European/Internationally Important Plant Area (IPA) for desmids (Brodie et al ., 2007). It has been chosen due to its species richness (100

species recorded), its long history of study and for the fact that it is a threatened priority habitat. Lower Bostraze has been designated as a County Wildlife Site (CWS).


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.