Turbellarian taxonomic database

Abstract / Notes

Ninety localities in Anglesey and Caernarvonshire, including 46 streams and 44 ponds and lakes, were examined
for triclads; only 9 were negative. Nine of the 10 British spp. were recorded. The rare Planaria torva was
the only absentee. Polycelis nigra is the most widespread sp. occurring in streams, ponds and lakes of a wide
variety. P .felina is confined to swift streams in the area and there is evidence that under certain
conditions it cannot tolerate low mineral and/or calcium content of the water. On Anglesey it occurs most
commonly on the n.-e. coast where water flow is suitable. Crenobia alpina is rare on Anglesey and not common
on the mainland. Phagocata vitta has not been found on Anglesey, but on the mainland it is a very
characteristic sp. of streams with seepage water on high ground. The following spp. occur in lowland ponds
and lakes Polycelis tenuis, P. hepta, Dugesia lugubris and Dendrocoelum lacteum, Bdellocephala punctata, an
uncommon sp. and the largest British fresh-water triclad, was found in Llyn Mymbyr.

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