Fróðskaparrit - 01.01.1991, Side 62

66
A NOTE ON THE OCCURENCE OF LAND PLANARIANS
and Reynoldson, 1981) as well as Denmark
(Mather and Christensen, 1991), Western
Norway and the south coast of Iceland (Lin-
droth, Andersson, Bódvarsson and Richter,
1973, p. 146).
The other species of land planarian, Ar-
tioposthia triangulata, a new species in the
Faroe Islands, originates from New Zealand
and was first discovered in 1963 in two
gardens in the vicinity of Belfast (Willis and
Edwards, 1977; Ball and Reynoldson, 1981).
It has expanded its distribution area and was
later found in the northern part of Scotland
in 1977 (Wakelin and Vickerman, 1979;
Blackshaw and Stewart, 1991), and also in a
greenhouse in Reykjavík, Iceland in 1990 (E.
Ólafsson, pers. comm.), but it is not known
to occur in Denmark or Norway.
Discussion
It would seem that the dispersal of land
planarians is made possible by an-
thropochorous transport via import of
plants containing soil from their native lo-
calities. This also seems to have been the case
for two other turbellarian species, Kontikia
andersoni Jones, from the Indo-pacific
region (Jones, 1981a) and Geoplana san-
guinea, native to Australia (Jones, 1981b).
Kontikia andersoni turned up in 1976 in
Northern Ireland, and Geoplana sanguinea
(Moseley) in 1980 on the Isle of Scilly. Ships
arrive in the Faroe Islands every week, with
all kinds of goods for Faroese households,
including plants. These boats load most of
their cargo in Denmark, but also visit
Western Norway and Scotland on passage,
and there are also connections with Iceland.
For many years potatoes have been bought in
Scotland and Denmark, transported on the
regular cargo ships, and then planted in the
Faroes. Since 1976 there has also been regu-
lar summer passenger ship traffic between
the Faroe Islands and Shetland/Scotland. In
the summer several Faroese travel to the
Northern part of Scotland as tourists, and it
is not prohibited to buy plants to take home,
thus also providing the possibility of import-
ing invertebrates or their egg capsules in the
surrounding soil.
In Denmark, Rhynchodemus terrestris is a
common species, so the import route is im-
possible to discover for this species. The situ-
ation is otherwise with Artioposthia trian-
gulata which has never been recorded in
Denmark (Mather and Christensen, 1991).
The most likely immigration route for this
species, then, is from Scotland in connection
with either the import of potatoes for plant-
ing or the purchase of potted plants.