BAERT, L

Bonte, Dries

Criel, Peggy

De Bakker, Domir

English

Ghent University Academic Bibliography

Most individuals in Belgium were found in pitfall trapsused for monitoring studies in the Flemish coastal dunes.Another specimen was captured with an arboreal eclectortrap (3) in a recently installed forest reserve in theProvince of East-Flanders. The first individuals were col-lected in the winter of 1999 in the Westhoek dune reserveat De Panne (18 males and two females in the periodbetween September 10th, 1999 and February 6th, 2000)and in the fossil dunes of Ghyvelde-Adinkerke, on theFrench-Belgian Border (20 males in the period betweenOctober 12th, 1999 and February 6th, 2000). During thisperiod, no individuals were collected in other sampleddune areas in Nieuwpoort and Oostduinkerke.Surprisingly, the following summer one male was foundon a dead tree-trunk in an open Beech-forest (Fagus syl-vatica) without substantial undergrowth (Kluisbergen). InOctober and November of 2000, D. graecus (three males)was for the first time found in the grey dune-area of theIJzer-estuary in Nieuwpoort, although this site has beenmonitored for terrestrial invertebrates since 1990 (2).During the same period, 15 males were captured in a duneslack of the Westhoek Nature Reserve. All individuals,KEY WORDS: Diplocephalus graecus, Araneae, first occur-rence, Mediterranean species, coastal dunes, climate change,invasion, expansionDiplocephalus graecus (O.-P. Cambridge, 1872) isknown as one of the most common erigonid spiders of theEuropean Mediterranean region (9). Until now the specieshas been recorded from Northern Africa (Algeria,Morocco, Tunisia ; 9, 10, 16, 17, 29, 21), Southern(France, Italy, Spain, Greece; 11, 12, 13, 14, 15, 16, 18,19, 20, 22) and Eastern Europe (Romania; 18), reachingits northern limit near Paris (17, 20). The recent capturesin Belgium indicate that its range is expanding further tothe north.Males measure 1.5 to 1.9 mm, females are a little larger:1.8 to 2.2 mm. D. graecus is a brownish species with adark grey abdomen; chelicerae and legs are yellowish toorange-brown and the sternum is of a darker brown. Theplacements of the trichobotrium and spines on the legs arecharacteristic for the genus Diplocephalus. As in mostmembers of the Erigoninae subfamily, males of thisspecies are easily distinguished by the shape of the malecephalic tubercle (Fig. 1A). Certainty about identificationcan be gained by checking the shape of the male palpaltibia, which lacks typical apophyses, in contrast to otherEuropean members of the genus (Fig.1B). The epigyne ofthe females has a typical wide median fissure with medianconstriction (Fig.1C).In the Mediterranean region, D. graecus occurs in awide variety of man-made and man-influenced habitatssuch as gardens, pastures, arable fields and short moun-tain grasslands. The species is also found in more naturalhabitats such as maquis, rough grassland, lake-bordersand saltmarshes (9, 16, 17).The invasive occurrence of the Mediterranean dwarfspi-der Diplocephalus graecus (O.-P. Cambridge, 1872) inBelgium (Araneae: Linyphiidae)Dries Bonte1, Peggy Criel1, Léon Baert2 and Domir De Bakker21 Ghent University, Dept. Biology, Research group Animal Ecology, Zoogeography and Nature Conservation, K.L.Ledeganckstraat 35, B-9000 Ghent, Belgium2 Royal Institute of Natural Sciences, Department of Entomology, Vautierstraat 29, B-1000 Brussels, BelgiumCorresponding author: D. Bonte, e-mail : dries.bonte@rug.ac.beBelg. J. Zool., 132 (2) : 171-173 July 2002SHORT NOTESFig. 1. – Male cephalothorax (A), palp structure (B) and epigyne(C) of Diplocephalus graecus (O.-P.-Cambridge) – scaleline=0.2 mm (9).except for one, were captured in thermophilous, sandy habi-tats (dune slacks, grey dunes, short dune grasslands andrecently cut scrubland with a large amount of bare sand).However, no other specimens were collected in other suit-able habitats (heathland, inland dunes) sampled elsewherein Belgium from early 1999 until October 2000 (8,12).In Fig. 2 we visualise the captures of the species inBelgium. If we pool our data from the two years, itbecomes clear that the species reaches its highest activityin the winter-period, although it can be present duringsummer and autumn (Fig. 3). For the Mediterraneanregion the same trend can be recognized: most individu-als of D. graecus were collected during the periodOctober-April (9). In general, summer records are veryrare in the south (9,20), which makes our phenology datahighly concordant with those from southern countries.Our data show that the species expands its range north-ward along the coastline in an invasive way, a phenome-non also observed in other southern insect and arachnidspecies (4,5,6,7,21). Our observations and the fact that insouthern regions D. graecus occurs in disturbed habitats,indicate that the species has a high dispersal power byDries Bonte, Peggy Criel, Léon Baert and Domir De Bakker172way of ballooning. The milder winter-temperatures alongthe coast in comparison with those of inland habitats (1),probably enables the species to survive and spread in ourregion. Because of its assumed high dispersal capacities,the follow-up of its expansion should reveal interestingdata on climate change and its effect on the spread ofsouthern species.We would like to thank Dr. R. Bosmans for checkingthe identification.REFERENCES1. AMPE, C. & R. LANGOHR (1996). Klimaat. In: PROVOOST &HOFFMANN (eds), Ecosysteemvisie voor de kust. Deel I :ecosysteembeschrijving. Universiteit Gent & Instituut voorNatuurbehoud, Brussel : 2-47.2. BAERT, L. & K. DESENDER (1993). De spinnenfauna van hetmilitair domein te Lombardsijde (Araneae). Nieuwsbr. Belg.Arachn. Ver., 8(1) : 15-20.3. BEHRE, G.F. (1989). Freilandökologische methoden zurerfassung der Entomofauna (Weiter- und Neuentwickelüngvon Geräten). Jber. Naturwiss. Ver. Wuppertal 42: 1-64. BONTE, D. (1994). Libellen Odonata in de duinstreek van deVlaamse Westkust : resultaten van een inventarisatiegedurende de periode 1990-1994. Gomphus, 10(2) : 39-44.5. BONTE, D. (1996). Een eerste broedgeval van de BijeneterMerops apiaster in Vlaanderen te Adinkerke (De Panne,West-Vlaanderen). Mergus, 10(1) : 199-202.6. BONTE, D. (1997). Het voorkomen van Hyles euphorbiae,Aricia agrestis, Hipparchia semele en Issoria lathonia in hetduingebied van de Vlaamse Westkust in 1996 (Lepidoptera).Phegea, 25(1) : 1-5.7. BONTE, D., M. HOFFMANN & J.-P. MAELFAIT (1999).Monitoring van het begrazingsbeheer in de Belgische kust-duinen aan de hand van spinnen. Nieuwsbr. Belg. Arachnol.Ver., 14(1) : 24-36.8. BONTE, D., W. DEKONINCK & P. GROOTAERT (2000). De spin-nenfauna van de Oost-Vlaamse binnenduinen: is er nog eenspecifieke fauna aanwezig? Nieuwsbr. Belg. Arachnol. Ver.,15(2) : 27-36.9. BOSMANS, R. (1996). The genera Araeoncus Simon,Delorrhipis Simon and Diplocephalus Bertkau in NorthernAfrica (Araneae: Linyphiidae: Erigoninae). Studies on NorthAfrican Linyphiidae VII. Belg. J. Zool., 126(2): 131-151.10. BRISTOWE, W.S. (1935). The spiders of Greece and the adja-cent islands. Proc. Zool. Soc. London, 1934 (4) : 733-788.11. DALMAS, R., de (1922). Catalogue des araignées récoltéespar le Marquis G. Doria dans l’île Giglio (Archipel Toscan).Ann. Mus. Civ. Stor. Nat. Genova, 50: 79-96.12. DE BAKKER, D., D. BONTE, W. DEKONINCK, V. VERSTEIRT &P. GROOTAERT (2000). Het effect van natuurontwikkeling opvoormalige akkers in Vlaanderen. Nieuwsbr. Belg. Arachnol.Ver., 15(3) : 57-9413. DENIS, J. (1933). Liste d’araignées receuillies dans ledépartement du Var. Ann. Soc. Hist. Nat. Toulon, 1932-1933(17): 85-102.14. DENIS, J. (1933). Chasses arachnologiques dans les Pyrénéesorientales (Région de Banyuls-sur-Mer et Vallespir). Bull.Soc. Hist. Nat. Toulouse, 65: 529-591.Fig. 2. – Captures of Diplocephalus graecus in Belgium in thesampled suitable habitats in the period 1999-2000.Fig. 3. – Phenology of Diplocephalus graecus in Belgium in theperiod 1999-2000.15. DENIS, J. (1934). Eléments d’une faune arachnologique de l’îlede Port-Cros (Var). Ann. Soc. Hist. Nat. Toulon, 18: 136-158.16. DENIS, J. (1964). Notes synonymiques. Bull. Soc. Hist. Nat.Toulouse, 99: 61-67.17. DENIS, J. (1968). Notes d’Aranéologie marocaines. X. Leserigonides du Maroc. Bull. Sci. Nat. Phys. Maroc, 47: 137-164.18. REIMOSER, E. (1919). Katalog der echten Spinnen (Araneae)des Paläarctischen Gebietes. Abh. Zool. bot. Ges. Wien,10(2) : 1-280.The invasive occurrence of the Diplocephalus graecus 17319. SIMON, E. (1881). Description d’Arachnides nouveaux dugenre Erigone. Bull. Soc. Zool. France, 6 : 82-91.20. SIMON, E. (1884). Les Arachnides de France, V. Roret. Paris :181-885.21. SLOSSE, W. (1995). Dicranopalpus ramosus (Opliones :Phalangidae), nieuw voor de Belgische fauna. Nwsbr. Belg.Arachnol. Ver., 10(1) : 11-13.22. THALER, K. (1977). Einige Linyphiidae (s.l.) aus Tunesien.Revue suisse Zool., 84: 557-564.Received: February 18, 2002Accepted: April 20, 2002

The invasive occurrence of the Mediterranean dwarfspider Diplocephalus graecus (O.-P. Cambridge, 1872) in Belgium (Araneae: Linyphiidae)

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The invasive occurrence of the Mediterranean dwarfspider Diplocephalus graecus (O.-P. Cambridge, 1872) in Belgium (Araneae: Linyphiidae)

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