Phylum: Miozoa Family: Peridiniaceae
Peridinium cinctum (O.F. Müller) Ehrenberg
A widespread and common species found in the plankton of pools, lochs and ditches
References:
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition) The Freshwater Algal Flora of the British Isles