ÚrtakFýra sløg av gráum undir steini eru staðfest í Føroyum:Trichoniscus pusillus Brandt, 1833, Ligia oceanica(Linnaeus, 1767), Oniscus asellus Linnaeus, 1758 ogPorcellio scaber Latreille, 1804. Í hesari kanning varðeinki nýtt slag funnið. Á 48 støðum vórðu grá undirsteini staðfest fyri fyrstu ferð, so saman við eldrikanningum eru tey nú staðfest á 59 støðum tilsamans.Hesi støð eru sett á kort. Orðskift verður um útbreiðsl-una.
AbstractAsurvey ofwoodlice has been conducted. Species foundwere: Trichoniscus pusillus Brandt, 1833, Ligiaoceanica,Oniscus asellusLinnaeus, 1758 andPorcellioscaber Latreille, 1804, and no new species were found.We were able to document the presence of woodlice in48 new locations, bringing the total to 59. Thedistribution found is discussed.
IntroductionThe Faroe Islands are located in the north-eastern Atlantic Ocean and comprise 18 is-lands. They have been free of ice since theWeichselian glaciation 9500 years ago, sincewhen an immigration of plants and animals
has occurred.During the last 1100 years, dis-persal by man to and within the Faroe Is-lands, has been in effect (Enckell, 1985). Itis quite possible that man has been the vec-tor which has transported some species ofwoodlice to and within the Faroes, e.g. inthe ballast of ships with agricultural tools.It is well known that exotic terrestrial in-vertebrates are accidentally introduced to theFaroes each year (e.g. Jensen and Sivertsen,2004; 2005; Bengtson et al., 2004). We donot know of any recently introduced wood-lice.Scharff (1904) published the first tworecords of woodlice from the Faroe Islandsfollowed by Lohmander (1929) and Steph-ensen (1929) who worked a large materialof terrestrial isopods andmarine crustaceans(Isopoda and Tanaidacea) collected on theFaroes.Ligia oceanica is a large species, about30mm long. It is an amphibian and occurs
Fróðskaparrit 54. bók 2006: 172-176
Distribution of Woodlice (Isopoda:Oniscoidea) in the Faroe Islands
Útbreiðsla av gráum undir steini(Isopoda: Oniscoidea) í Føroyum
Janus Hansen1 and Jens-Kjeld Jensen21 Hammershaimbsvegur 16, FO-360 Sandavágur, Faroe Islands. Email: janush@ngs.fo2 Í Geilini 37, FO-270 Nólsoy, Faroe Islands. Email: jkjensen@post.olivant.fo

ÚTBREIÐSLA AV GRÁUM UNDIR STEINI (ISOPODA: ONISCOIDEA)Í FØROYUM
mainly on rocky beaches under stones androcks. When disturbed it can either disap-pear down between the rocks, or drop intothe water. Oniscus asellus and Porcellioscaber are both about 10-15mm long. Bothare rather common in deciduous woods and“hagi” (i.e. outfield); P. scaber also occursin houses and e.g. birds’nests. Trichoniscuspusillus is the smallest species in the islands,about 3-5mm long. It occurs in the samehabitats as the other two terrestrial species.The three firstmentioned species have a nor-mal reproduction, but T. pusillus can alsobe parthenogenetic, implying that its ca-pacity for dispersal after immigration ishigher than for the others.None of the isopods are pests; they aremainly nocturnal and not usually seen dur-ing daytime.Woodlice are predominantly herbivorous(Hopkin, 1991).According to Poulsen et al. (1998)wood-lice are either called ‘grótlús’or ‘grátt undir
steini’in Faroese, but they are frequently re-ferred to by different names.On the islandof Skúvoy they are referred to as ‘veggjalús’(which is actually the bedbug, Cimex lectu-larius) (pers.comm. Birgir Thomsen, Jóan-nis Mikkelsen). Complicating matter fur-ther, bristletails (Thysanura) are referred toas ‘veggjalús’ in the village of Hvannasund(pers. comm. Hans Jørgen Nysted).
Material and MethodsJ-K. J. has systematically collectedwoodlicesince 2001, over a five year period, and hasbeen in contact with numerous people,which have assisted with collecting on allthe islands, with the exception of LítlaDímun.All collected specimen are preserved in70% ethanol (a few are slide mounted ac-cording to the method employed by Palma(1978). The collected woodlice were iden-tified by J-K. J. using a stereo loupe and thekey by Hopkin (1991).
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Figure 1. Oniscus asellus

DISTRIBUTION OFWOODLICE (ISOPODA: ONISCOIDEA)IN THE FAROE ISLANDS174
Figure 2. The sites where four species of woodlice were found in the Faroes. Dots and circles representpositive finds.
Porcellio scaber Oniscus asellus
Ligia oceanicaTrichoniscus pusillus

ÚTBREIÐSLA AV GRÁUM UNDIR STEINI (ISOPODA: ONISCOIDEA)Í FØROYUM
Three of the four found speciesL. ocean-ica, O. asellus and P. scaber can be identi-fied in the field,which iswhy only 485 spec-imen were collected of these species.All species new to an area have beenidentified by collected specimen. Figure 2shows inwhich Jocations species have beenfound in this study. It also includes those ofLohmander (1929) and Stephensen (1929)and Bengtson pers.comm.Voucher specimens representing all therecords, have been deposited in the collec-tions of theMuseumofNaturalHistory,Tór-shavn, Faroe Islands.During 1978 and 1979 extensive field-work was conducted on the Faroes (Bengt-son, 1979) resulting in check-lists of severalgroups of invertebrates, part of this mate-rial has not been published until now.
ResultsThe distribution of the species differ (Fig.2). In the areas where it is found, P. scaberseems to be themost abundant, i.e. it is foundin most locations. But it is absent from thecentral-north part of the Faroes, with the ex-ception of one record from the village of Eiðiprior to 1929. It has been found in three lo-cations in the northeastern area, and in fourlocations in the northwestern area. O. asel-lus shows a similar distribution, with onlyone recorded location north of 62º 05’(priorto 1929.Not many individuals have been foundof T. pusillus. They seem to be evenly dis-tributed, throughout the Faroes, but notmuch else can be deduced about the distri-bution. L. oceanica too seems to be evenly
distributed, but has been found in more lo-cations than T. pusillus.
DiscussionNo new species have been added to the listsof Lohmander (1929) and Stephensen(1929). The numbers of species from neigh-bouring areas are 37 in Britain and Ireland(Hopkin, 1991), 4 in the Shetlands, 5 in theOrkneys, 9 in the Hebrides (Harding andSutton, 1985) and 7 in Iceland (Erling Ólaf-sson in litt.).Woodlice are most commonly found inresidential areas in the Faroe Islands. T.pusillus, having been found in 18, 19 and22 locations, respectively, than P. scaber,which has been found in 41 locations.The fact that we have been unable to findP. scaber in Kalsoy, Kunoy, Borðoy, Viðoy,could be due to oversight, but communica-tion with local people confirm our negativeresults, and that woodlice are at least asscarce as in Fugloy and Svínoy.P. scaberwas reported seen in the villageof Húsar in the island of Kalsoy (Joan Isak-sen pers. comm.) around 2003, but a thor-ough search in 2005 turned out negative.Wehave no explanation as to why woodliceseemingly are more scarce to the north ofthe Faroes.
AcknowledgementsWe are grateful to: Óla Jákup and Sunnuvaúr Dímun, Bjarni Garðshorn, BenjaminIsaksen, Joan Isaksen,Áslakkur Johannesen,Rodmund á Kelduni, Jóannis Mikkelsen,Marita Gulklett, Hans Jørgen Nysted, Ann-leyg Patursson, Marjun Arge Simonsen,Hans Eli Sivertsen, Alf Sørensen†, Karstin
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DISTRIBUTION OFWOODLICE (ISOPODA: ONISCOIDEA)IN THE FAROE ISLANDS
Vang,AtliVilhelm, ErlingÓlafsson, Icelandand Dorete Bloch for loan of equipment,P.H. Enckell for added information, andSven-Axel Bengtson for valuable data.
ReferencesBengtson, S.A. and Hauge, E. 1979. Terrestrial Inverte-brates of the Faroe Islands: I. Spiders (Araneae):Check-list, distribution, and habitats. Fauna Norv. B26: 59-83.Bengtson, S-A. Enckell, P.H., Bloch, D. and Hauge, E.2004. Spiders (Araneae) in the Faroe Islands: an an-notated checklist and an update on inter-island dis-tributions. Fróðskaparrit. 52:54-72.Enckell, P.H. 1985. ISLANDLIFE:Agency ofman upondispersal, distribution, and genetic variation inFaroese populations of terrestrial invertebrates. PhDThesis. Dept. ofAnim. Ecol. LundUniversity. 1-112.Harding, P.T. and Sutton, S.L. 1985.Woodlice in Britainand Ireland: Distribution and Habitat. Natural envi-ronment research council. Lavenham Press. 1-151.Hopkin, S. 1991. A Key to the Woodlice of Britain andIreland. Field Studies 7 no. 4: 599-650., 16 pp. col.Plates. Field Studies CouncilJensen, J-K. and Sivertsen H.E. 2004. Nye og sjældnefund af sommerfugle på Færøerne. Lepidoptera bindVIII, nr. 7:225-233.Jensen, J-K. and Sivertsen, H.E., 2005. Nye og sjældnefund af sommerfugle på Færøerne 2004.Lepidoptera8: 309-316.Lohmander,H. 1929. Isopoda terrestria. In: Jensen,Ad.S.,Lundbeck, W., Mortensen, Th. and Spärck, R. (eds).1928-1937. The Zoology of the Faroes II(I) 25: 1-7.Palma, R.L. 1978. Slide-mounting of lice: a detailed de-scription of the Canada balsam technique. New Zea-land Entomologist 6(4): 432-436.Poulsen, J.H.W., Simonsen, M., Jacobsen, J. í L., Jo-hansen,A. and Hansen, Z.S. 1998.Føroysk Orðabók,Føroya Fróðskaparfelag. 1-1483,Scharff, R.F. 1904. Isopoda. In: Annandale, T.N. (ed.):Contributions to the terrestrial Zoology of the Faroes.Proc. Roy Phys. Soc. Edinburgh 15. 1901-1904: 154-155.Stephensen,K. 1929.Marine crustacea isopoda and tanai-dacea. In: Jensen, Ad.S., Lundbeck, W., Mortensen,Th. and Spärck, R. (eds). 1928-1937. The Zoology ofthe Faroes II(I) 25: 1-23.
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