Cornish Biodiversity Network  -  Supporting Wildlife Recording

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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.

Dytiscus dimidiatus - A great diving beetle

Range & Status

Primarily a species of fens and grazing levels, though there are outlying records from

Cornwall and Durham. A national distribution map is provided in Foster (1985).

Regional Distribution

Two single records: from a grassy pool on Red Moor in 1972 (Foster, 1973) and found by S.P. Jones at Brea, near Redruth in 1982.

Habitat & Ecology

Occurs in ponds, ditches and open fen, usually where there is plenty of submerged and emergent vegetation.


Habitat loss, for example, through drainage and intensification of agriculture, or lowering of water tables via abstraction schemes.

00 Conservation

Red Moor is a Cornwall Wildlife Trust reserve.


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.