Medical and Veterinary Entomology(1998)12, 215–216

S H O R T C O M M U N I C AT I O N

Ixodes frontalis on the Baltic island of Gotland,Sweden

L A R S L U N D Q V I S T,1 J E R E M Y S . G R AY2 and PA U L D . H I L LYA R D 3

1National Museum of Natural History,2 Department of Environmental Resource Management, Faculty of Agriculture, University

College of Dublin, Republic of Ireland, and3 Department of Entomology, Natural History Museum, London, U.K.

Key words. Geographic distribution, birds, new record.

Ticks (Acari: Ixodidae) collected while ringing birds on theisland of Gotland were supplied to us. Among the materialthere were two individuals of a species not previously reportedfrom Sweden,Ixodes frontalisPanzer. The birds had beencollected at Faludden’s lighthouse,µ 7.5 km SE of the churchof Oja, south Gotland (N 57°009, E 18°249). Gotland is anisland situated in the centre of the Baltic. One tick was a partlyengorged female attached to the neck of a willow warbler(Phylloscopus trochilus) caught on 5 May 1993, and the othera partially fed nymph, on the neck of a redstart (Phoenicurusphoenicurus) caught on 11 May 1993.

The main distribution ofIxodes frontalis [called I. pariLeach by Arthur (1963)] is south and central Europe, includingRussia, but it is found as far east as the Philippines. Thespecies is a typical bird parasite, mainly found on passerines,but also on owls and falcons. Several bird parasites aredistributed widely by their hosts, e.g.Hyalomma marginatumKoch (Jaensonet al., 1994). This species has its maindistribution around the Mediterranean, but has occasionallybeen collected in Sweden on newly arrived migratory birds.The information available so far is not sufficient to statewhetherI. frontalis is an established species on the island ofGotland. An alternative interpretation is that the ticks werecarried from say the Baltic countries, where the speciesis known.

There are now eightIxodesspecies found on birds in Sweden(Jaensonet al., 1994; Talleklint, 1996). Of these, one individualof Ixodes (Ixodes) persulcatusSchulze, was collected on anisland in the Gulf of Bothnia, St. Fja¨deragg µ 40 km E Umeå(northern part of Sweden). This species is, however, not a typicalbird parasite.Ixodes (Ceratixodes) urieand I. (Scaphixodes)unicavatusare only found on birds nesting on bird-rocks andI. (Scaphixodes) caledonicuson other rock-nesting species,e.g. peregrine (the two species ofScaphixodesare known fromSweden only from single specimens collected in the early

Correspondence: Lars Lundqvist, Lund University, Departmentof Systematic Zoology, Helgonava¨gen 3, S-223 62 Lund, Sweden.E-mail: Lars.Lundqvist@zool.lu.se

© 1998 Blackwell Science Ltd 215

part of the twentieth century (Jaensonet al., 1994). Ixodes(Pholeoixodes) lividusis specific on sand martins. Theremaining three species can be found fairly commonly onpasserines and other birds. The three species can be separatedusing the following key:

Females:1. Long postero-internal spur on coxa I (Fig. 1b,c), sclerotized

parts dark brown to black ...................................................2– Coxa I rounded, without spur (Fig. 1a), sclerotized parts

light brown..............................I. (Pholeoixodes) arboricola2. Auriculae (bud-like extensions ventrally on each side of

basis capitulum), inserted posteriorly to the palps (Fig. 1b)...................................................I. (Trichotoixodes) frontalis

– No such extension on basis capitulum (Fig. 1c) ....................................................................................I. (Ixodes) ricinus

Nymphs:1. Long postero-internal spur on coxa I, small postero-external

spurs on all coxae (Fig. 3b,c), sclerotized parts dark brownto black ................................................................................2

– No spurs on coxae (Fig. 3a), sclerotized parts light brown............................................................................I. arboricola

2. Basis capitulum dorsally approximately as broad as long,i.e. the distance between posterior edge of the shield andthe insertion of the hypostome is as long as the distanceacross the shield. Clear extensions at the corners of thecapitulum (Fig. 3c) .................................................I. ricinus

– Basis capitulum broader than long. Extensions at the cornersof the capitulum are vague (Fig. 3b) ..................I. frontalis

Acknowledgements

Collectors were Ingvar, Torgny, and Andreas Nordin and LarsÅke Pettersson. Thanks are due to Dr Agustı´n Estrada-Pen˜a,Zaragoza, Spain, for confirming our determination.

216 Lars Lundqvist et al.

Fig. 1. Ventral aspect of basis capitulum and coxae I – IV. Femalesof threeIxodesspecies that can be found on passerine birds other thansand martins in Sweden. (a)Ixodes arboricola(Sk. Sodra Sandby,ex:‘Flycatcher, nestling’), coxae of left side; (b)Ixodes frontalis(Gtl.Faluddens lighthouse,ex: willow warbler, engorged), coxae of rightside; (c)Ixodes ricinus(Gtl. Fåro, ex: vegetation). Scale bar 0.5 mm.

Fig. 3. Ventral aspect of basis capitulum and coxae I – IV. Nymphsof threeIxodesspecies. (a)Ixodes arboricola(Sk. Sodra Sandby,ex:‘Flycatcher, nestling’), coxae of left side; (b)Ixodes frontalis(Gtl.Faludden lighthouse,ex: Redstart), coxae of right side; (c)Ixodesricinus (Gtl. Fåro, ex: vegetation), coxae of left side. Scale bar 1.0 mm.

© 1998 Blackwell Science Ltd,Medical and Veterinary Entomology, 12, 215–216

Fig. 2. Dorsal aspect of basis capitulum and scutum. Females of threeIxodesspecies. (a)Ixodes arboricola(Sk. Sodra Sandby,ex: ‘Flycatcher,nestling’); (b) Ixodes frontalis(Gtl. Faludden lighthouse,ex: willowwarbler); (c) Ixodes ricinus (Gtl. Fåro, ex: vegetation). Scale bar0.5 mm.

ReferencesArthur, D.R. (1963)British Ticks. Butterworths, London.Hillyard, P.D. (1996)Ticks of Northwest Europe. Synopsis no. 52,

Linnean Society of London.Jaenson, T.T.G., Ta¨lleklint, L., Lundqvist, L., Olsen, B., Chirico, J. &

Mejlon, H. (1994) Geographical distribution, host associations, andvector roles of ticks (Acari: Ixodidae, Argasidae) in Sweden.MedicalEntomology, 31, 240–256.

Talleklint, L. (1996) Transmission of Lyme borreliosis spirochetesat the tick vector–mammal reservoir interface.Acta UniversitatisUpsaliensis, Uppsala, Sweden.

Accepted 17 November 1997