01758nas a2200157 4500008004100000020001400041245012400055210006900179260003500248300001400283490000800297520119400305100002301499700002101522856005701543 1979 eng d a1469-799800aPredation on snails by three species of triclad and its bearing on the distribution of Planaria torva in Britain0 aPredation on snails by three species of triclad and its bearing  bBlackwell Publishing Ltdc1979 a459 - 4840 v1893 a

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.

1 aReynoldson, T., B.1 aPiearce, Bronwen uhttp://dx.doi.org/10.1111/j.1469-7998.1979.tb03974.x02189nas a2200157 4500008004100000020001400041245010300055210007000158260003500228300001400263490000600277520164900283100002301932700001901955856005701974 1976 eng d a1365-242700aThe food of Planaria torva (Müller) (Turbellaria-Tricladida), a laboratory and field study0 afood of iPlanaria torvai Müller TurbellariaTricladida a laborato bBlackwell Publishing Ltdc1976 a383 - 3930 v63 a

The food of Planaria torva was examined in the laboratory by exposing a range of potential prey to the triclad and observing prey mortality. Under these conditions P. torva fed mainly upon tubificid oligochaetes and gastropods. The former activity was regarded as untypical of the field situation and due to limitations of the laboratory habitat. The food of P. torva was determined in the field by taking monthly samples from October 1967 to May 1969 of a population living in Linlithgow Loch, West Lothian, Scotland. A serological technique was used to examine the gut contents of the field triclads. For reasons explained in the text, the prey organisms tested for serologically were gastropods, oligochaetes (Tubificidae), Asellus and chironomid larvae. Planaria torva fed most extensively on Gastropoda, Asellus was the second main food while Tubificidae and Chironomidae were taken only seasonally and in small numbers. The limited extent of feeding on tubificids supports the laboratory data. Small P. torva gave proportionately fewer positive reactions to the prey antisera than large individuals. This was explained by the fact that small individuals occurred most frequently in the warmer months and took smaller meals; both of these features shorten the detection period of food in the gut and therefore give fewer reactions. The diet of small and large P. torva was similar in the field and showed considerable overlap with that of Dugesia polychroa. The food of Polycelis tenuis, Dendrocoelum lacteum and Dugesia polychroa in Linlithgow Loch was described on an annual basis and the results confirmed earlier observations.

1 aReynoldson, T., B.1 aSEFTON, A., D. uhttp://dx.doi.org/10.1111/j.1365-2427.1976.tb01623.x01875nas a2200169 4500008004100000022001400041245013300055210006900188260002900257300001300286490000800299520128400307100001801591700002301609700001601632856005701648 1969 eng d a1469-799800aThe taxonomy, habitat and distribution of the freshwater triclad Planaria torva (Platyhelminthes: Turbellaria) in Britain0 ataxonomy habitat and distribution of the freshwater triclad iPla bBlackwell Publishing Ltd a99–1230 v1573 a

Planaria torva was described originally by O. F. Müller 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.

1 aBall, Ian, R.1 aReynoldson, T., B.1 aWarwick, T. uhttp://dx.doi.org/10.1111/j.1469-7998.1969.tb01691.x