@article {1707, title = {Predation on snails by three species of triclad and its bearing on the distribution of Planaria torva in Britain}, journal = {Journal of Zoology}, volume = {189}, year = {1979}, month = {1979}, pages = {459 - 484}, publisher = {Blackwell Publishing Ltd}, abstract = {

Dugesia polychroa, D. lugubris and Planaria torva preyed upon snails of differing morphologies and while the Dugesia spp. fed approximately in proportion to snail abundance, PL torva was more selective on Potamopyrgus jenkinsi. The incidence of feeding on four snail taxa by the Dugesia spp. was significantly correlated and differed strikingly from that of PI. torva where feeding was related to its annual life cycle. Large peaks of feeding coincided in the Dugesia spp. for the four snail types; this was attributed to snail vulnerability being increased by environmental disturbance. Comparison of feeding by Dugesia spp. in the presence and absence of PI. torva indicated that severe competition was occurring for food with PI. torva having a food refuge in P. jenkinsi. The distribution of PI. torva in Britain is largely confined to productive habitats in the Glasgow-Edinburgh and East Anglia regions. It is concluded that historical rather than ecological events have played the major part in its distribution to date. The strong association of PL torva with port areas and the canal system suggests that it is a recent introduction via the timber trade with Fennoscania.

}, isbn = {1469-7998}, url = {http://dx.doi.org/10.1111/j.1469-7998.1979.tb03974.x}, author = {Reynoldson, T. B. and Piearce, Bronwen} } @article {JZO:JZO99, title = {The taxonomy, habitat and distribution of the freshwater triclad Planaria torva (Platyhelminthes: Turbellaria) in Britain}, journal = {Journal of Zoology}, volume = {157}, number = {1}, year = {1969}, pages = {99{\textendash}123}, publisher = {Blackwell Publishing Ltd}, abstract = {

Planaria torva was described originally by O. F. M\üller in 1774 under the generic name Fasciola. The synonyms arising since have been critically evaluated and the many varied morphological descriptions of this species are reviewed. The identity of this species in Britain has been confirmed by detailed examination of external and internal anatomy and it is shown that Planaria torfrida, described from Britain by Perkins (1928), is a synonym of Planaria torva. Dugesia lugubris (Schmidt, 1862) is the species most likely to be confused with Planaria torva and convenient methods of separating these species are described. The validity of all available British records has been examined and new localities described. Planaria torva occurs in England, Scotland and Ireland but has a markedly discontinuous distribution. There are real concentrations of habitats in the Edinburgh and Glasgow areas where the species also forms a larger proportion of the triclad population than usual. The species is markedly eurytopic and occurs in a wide range of lotic and lentic habitats, although most of them are calcium rich by British standards. It is not yet possible to offer a sound explanation for these facts because the ecology of Planaria torva is insufficiently known.

}, issn = {1469-7998}, doi = {10.1111/j.1469-7998.1969.tb01691.x}, url = {http://dx.doi.org/10.1111/j.1469-7998.1969.tb01691.x}, author = {Ball, Ian R. and Reynoldson, T. B. and Warwick, T.} }