B. Boag et al., LIMITATIONS TO THE DISTRIBUTION AND SPREAD OF TERRESTRIAL FLATWORMS WITH SPECIAL REFERENCE TO THE NEW-ZEALAND FLATWORM (ARTIOPOSTHIA-TRIANGULATA), Pedobiologia, 42(5-6), 1998, pp. 495-503
Factors affecting the spread and establishment of aquatic and terrestr
ial planarians are reviewed. The three main factors identified as limi
ting the spread of terrestrial planarians were temperature, moisture (
relative humidity) and availability of a suitable source of food. Temp
erature was considered unimportant and unlikely to restrict the distri
bution of the New Zealand flatworm (Artioposthia triangulata) in the B
ritish Isles and some other parts of north western Europe. The importa
nce of having sufficiently high relative humidity to allow movement an
d hunting may limit the distribution of A. triangulata, as might the r
estricted distribution of food resources (earthworms) due to acidic so
ils. Once established, intraspecific competition for food probably res
tricts flatworm population site. There was little evidence to suggest
that predation, parasites or diseases were likely to be important in c
ontrolling numbers of A. triangulata.