The distribution of Sphaeriidae in rivers and streams of central southern England

Collections of Sphaeriidae from 124 sites on rivers and streams in central southern England yielded two Sphaerium and eleven Pisidium species. P. casertanum and P. personatum were recorded most frequently from the intermittent headwaters, while S. lacustre, S. corneum, P. henslowanum and P. hibernicum showed a preference for sites with a channel width exceeding 25 m. An analysis of association between species indicated two groupings. One group (P. amnicum – P. henslowanum – S. lacustre – P. hibernicum) had a linear structure; the other (P. subtruncatum – P. personatum – P. milium – P. nitidum – P. pulchellum) had more between-species associations.