In 2013 and 2015 several specimens of the opilionid Platybunus pinetorum (C.L. Koch, 1839) were found in Sweden in two different places almost 500 kilometers from each other. The species was not previously known in the country. The discovery initiated a survey of specimens reported as Rilaena triangularis (Herbst, 1799) on two Swedish web pages, in search for misidentified P. pinetorum. A further three specimens of the new species were found, indicating that it is already rather widespread in southern Sweden

De Smedt, Pallieter

Fritzén, Niclas R.

Rinne, Veikko

Sunhede, Monika

Uddström, Annika

Van de Poel, Sam

English

Journal.fi

Memoranda Soc. Fauna Flora Fennica 91, 2015 • Fritzén et al. 37IntroductionIn July 2015, several specimens of a dark and in-teresting looking opilionid were seen and photo-graphed by the first and third authors in Huddinge in central Sweden. The specimens were found on trunks of old pine trees (Pinus sylvestris) but also by beating lower branches of Norway spruce (Pi-cea abies) and on moss on ground layer. The spe-cies turned out to be Platybunus pinetorum (C. L. Koch, 1839), which was not previously report-ed in Sweden or Fennoscandia (Stol 2007). Its congener Platybunus bucephalus (C. L. Koch, 1835) was previously reported in Finland, but all checked specimens turned out to be juvenile Rilaena triangularis (Herbst, 1799) (Uddström et al. 2013). Later on it turned out that sixteen spec-imens of P. pinetorum had already been caught in two forest patches separated from each other by Platybunus pinetorum (Arachnida, Opiliones) new to SwedenNiclas R. Fritzén, Veikko Rinne, Monika Sunhede, Annika Uddström, Sam Van de Poel & Pallieter De SmedtFritzén, N. R. & Rinne, V., Zoological Museum, University of Turku, FI 20014 Turku, Finland. E­mails:­nrfritzen@gmail.com,­veikko.rinne@utu.fi­ Sunhede, M., Torpavägen 62, SE-591 46 Motala, Sweden. E-mail: monikasunhede@hotmail.com Uddström, A., Finnish Environment Institute, Natural Environment Centre, P.O. Box 140, FI-00260­Helsinki,­Finland.­E-mail:­annika.uddstrom@ymparisto.fi­­ Van de Poel, S., Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. E-mail: samvandepoel@me.com De Smedt, P., Forest & Nature Lab, Ghent University, Geraardsbergsesteenweg 267, 9090 Melle (Gontrode), Belgium. E-mail: pallieter.desmedt@ugent.beIn 2013 and 2015 several specimens of the opilionid Platybunus pinetorum (C.L. Koch, 1839) were found in Sweden in two different places almost 500 kilometers from each other. The species was not previously known in the country. The discovery initiated a survey of specimens reported as Rilaena triangularis (Herbst, 1799) on two Swedish web pages, in search for misidentified P. pinetorum. A further three specimens of the new species were found, indicating that it is already rather widespread in southern Sweden.a road in southern Sweden (Svedala) using pitfall traps during the European smallFOREST project in 2013. Since especially juvenile R. triangula-ris can fairly easily be mixed up with Platybunus spp. on general habitus, we conducted a survey of specimens reported as R. triangularis togeth-er with photographs on Artportalen (www.artpor-talen.se, a web-page for reporting Swedish spe-cies observations) and specimens at least tenta-tively determined as R. triangularis on the Face-book page of Swedish spiders ”Spindelnätet”. ResultsIn the early summer of 2013, fifteen adult fe-males were caught in ten different pitfall traps lo-cated in two nearby forests is southern Sweden (Svedala). The traps were active from 7.6.2013 nda Soc. Fauna Flora Fennica 91: 37–40. 2015Fritzén et al. • Memoranda Soc. Fauna Flora Fennica 91, 201538to 20.6.2013. Twelve of these individuals were caught in the centers of the forests and the other three at the W-NW edge of one of the forests. Lat-er in the summer of the same year, one additional adult female was caught in one of the aforemen-tioned forests (pitfall trap active from 22.7.2013 to 4.8.2013). This pitfall trap was also located in the center of the forest. Skåne: Svedala, Skabersjö, Västrabyskogen, 15 ad. ♀, 7.6.2013 – 20.6.2013 and 1 ad. ♀, 22.7. 2013 – 4.8.2013 (leg. Sam Van de Poel). Among the R. triangularis with photos on Art-portalen (n=53) we did not find any misidentified P. pinetorum. On Spindelnätet (n=13) we found three specimens that we consider belonging to P. pinetorum, all from the southwestern part of Swe-den (one of these was also reported on Artporta-len but without picture). Bohuslän: 1 juv., Gothenburg, Hisings Kärra, 12.3. 2015 (leg. Kjell Nilsson); Småland: 1 ad. ♀ or subad., Jönköping, Torpa, Ladugårdsgatan, 26.5.2015 (leg. Mar-tin Sjödahl); Halland: 1?subad., Varberg, Gässlösa ravin, 26.5.2015 (leg. David Andersson). In addition the only eastern record and the northernmost one is the one found by us. Södermanland: Several ♀♀, Huddinge, Gladö (Sofie-lund landfill site), 24.7.2015 (leg. N.R. Fritzén & M. Sun-hede) (Figs 1 & 2).European P. bucephalus are clearly shorter. The male pedipalpal tarsus of P. bucephalus is thick-ened at the basal part, whereas the pedipalpal tar-sus of male P. pinetorum is simple. Females of P. bucephalus have a median apical spine on their pedipalpal femora, which is lacking in P. pineto-rum (Martens 1978, Wijnhoven 2009). However it is notable that this spine is present in juveniles of both above mentioned Platybunus species, and also in juveniles (but not in adults) of Rilaena tri-angularis.Platybunus pinetorum can be confused with the common Rilaena triangularis, which is usu-ally pale yellowish brown when adult. The pe-dipalps of R. triangularis are similar to the ones of P. pinetorum, but the femoral spines are short-er than the width of the femur and they are also more conical. The ocularium of R. triangularis is narrower, with a width of only 1.2–1.3 times its length. The ocularium is also usually concolorous with the surrounding prosomal region. Males of R. triangularis are easily identified by the trian-gular process on their chelicerae. Juveniles of P. pinetorum and R. triangularis are sometimes very similar, but the shape and colour of the ocularium in addition to the length of the spines of the pedi-palpal femora can be used for their identification as in adults but with some precaution.Distribution and habitatPlatybunus pinetorum originates from the moun-tainous areas of Central Europe (Martens 1978). Over the last few decades it has spread northwards and to more low-lying areas. Nowadays P. pine-torum is widely distributed in Central Europe, yet scarce in many areas. The northern limits of the known distribution of the species have previously been Denmark and the United Kingdom. P. pine-torum was discovered for the first time in the UK in 2010 and in Denmark in 2013 (Wijnhoven & Noordijk 2011, Enghoff et al. 2014).Platybunus pinetorum occurs mainly in de-ciduous and mixed forests. It prefers cool, damp and shady surroundings. Adult and subadult spec-imens can be found on tree trunks and on shrubs in the herbaceous layer, and based on our obser-vations also on lower branches of spruce. The Swedish specimens have been found in mixed IdentificationAll Platybunus species are characterized by a very broad ocularium (breadth = 1.5× length), which is situated close to the anterior edge of the prosoma (distance 0.25–0.5 times the length of ocularium). The yellowish brown ocularium also usually contrasts well with the darker prosoma. The pedipalps of Platybunus have distinctively long femoral spines and a long apophysis on pa-tella and tibia. The body is slender and especially the male opisthosoma is clearly tapering posteri-orly (Martens 1978). Platybunus pinetorum is a long-legged and rather dark coloured opilionid. The body length of males is 5.1–5.8 mm and of females 7.0–8.1 mm. Males are almost black, and females dark brown with a well-defined saddle bordered with white in the anterior part. The hind femora reach beyond the opisthosoma by 0.6 of their lengths in males and 0.3 in females. The legs of the Central Memoranda Soc. Fauna Flora Fennica 91, 2015 • Fritzén et al. 39evergreen/deciduous forests, in a ravine in a beach forest and on an apple tree in a garden. The specimens from the pitfall traps in Svedala were caught in deciduous forest dominated by Syc-amore maple (Acer pseudoplatanus L.), mixed with birch (Betula sp.) and some larch (Larix sp.). A shrub layer was absent. The three individuals caught at the edge of the forest were found under oak trees (Quercus robur L.), with elm (Ulmus glabra Huds.) and hawthorn (Crataegus monogy-na Jacq.) in the understory. Juveniles live in the litter layer. Unlike most European opilionids (but similar to e.g. R. trian-gularis) P. pinetorum overwinters as a juvenile (Wijnhoven 2009, Wijnhoven & Noordijk 2011). Adults can be found in the early summer, but little is known about the phenology in its new northern habitats. Our observations indicate that adult fe-males can be found at least until late July.ParthenogenesisAs previously suggested by Wijnhoven and Noordijk (2011) for this species in The Nether-lands, P. pinetorum would be able to reproduce in a parthenogenetic way beside normal sexual reproduction. It is difficult to draw conclusions based on the few observations in Sweden so far, but because all the specimens, the sex of which is known, are female, this could support the hy-pothesis. This adaptation can make it easier for the species to colonise new areas. ConclusionsThe several recent findings of P. pinetorum indi-cate that it is already rather widespread in South-ern Sweden as far north as Södermanland and Bo-Fig. 1. Closeup of Platybunus pinetorum ♀ in dorsal view (Huddinge, Sweden), showing the dark colouration and the very broad ocularium. Photo: N.R. Fritzén.Fig. 2. Platybunus pinetorum ♀ in lateral view showing the long ventral spines on the pedipalpal femur. Photo: N.R. Fritzén.Fritzén et al. • Memoranda Soc. Fauna Flora Fennica 91, 201540huslän. Since 2012, Finnish Opiliones have thor-oughly been studied as a part of the research pro-gramme of deficiently known and threatened for-est species (PUTTE), resulting in several species new to Finland (Uddström et al. 2013). However, this project has provided no indices that P. pine-torum would occur in Finland yet.Acknowledgements: We are grateful for the grant provid-ed by the Stockholm Entomological Society, which made it possible for the first and third authors to visit the site in Huddinge where P. pinetorum was found. We also wish to thank Kira Malmsten, who kindly provided us with ac-commodation during this stay. Jörg Brunet and Kent Hans-son from the Swedish University of Agricultural Sciences (SLU) are acknowledged for their help with installing and collecting the pitfall traps in southern Sweden and their great company in the field. We thank Luc De Bruyn for su-pervising the master thesis of Sam Van de Poel, making it possible for Sam to spend a lot of time on identifying Har-vestmen. Finally, we would like to thank the whole small-FOREST consortium for making the pitfall trapping possi-ble (https://www.u-picardie.fr/smallforest/uk/).ReferencesEnghoff, H., Pedersen, J. & Toft, S. 2014: Danske mejere – en fauna i vækst. — Entomologiske Meddelelser 82: 1–12.Martens, J. 1978: Spinnentiere, Arachnida: Weberknechte, Opiliones. — Die Tierwelt Deutschlands 64: 1–464.Stol, I. 2007. Checklist of Nordic Opiliones. — Norw. J. Entomol. 54: 23–26. Uddström, A., Rinne, V. & Pajunen, T. 2013: Opiliones new to Finland and an updated checklist. — Memo-randa Soc. Fauna Flora Fennica 89: 1–3.Wijnhoven, H. & Noordijk, J. 2011: Platybunus pineto-rum, een volgende hooiwagen die Nederland verovert (Opiliones: Phalangiidae). — Nederlandse Faunisti-sche Mededelingen 36: 9–14.Wijnhoven, H. 2009: De Nederlandse hooiwagens (Opi-liones). Entomologische Tabellen 3. Supplement bij Nederlandse Faunistische Mededelingen. — Neder-landse Entomologische Vereniging, Museum Natura-lis & EIS-Nederland, Leiden. 117 pp.

Platybunus pinetorum (Arachnida, Opiliones) new to Sweden

Fritzén, Niclas R

Ghent University Academic Bibliography

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Platybunus pinetorum (Arachnida, Opiliones) new to Sweden

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