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mollusca  marine mollusca

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SPIDERS, SCORPIONS & PSEUDOSCORPIONS

It would appear that little is known about the spider fauna of Thásos. In a comprehensive monograph on the jumping spiders (Salticidae) of Greece, Metzner (1999) mapped the recorded distribution of all 121 species but was unable to include a single record from Thásos. Similarly, Thaler et al (2000) comment on the distribution of seventeen of the forty or so wolf spiders (Lycosidae) reported from Greece, again without records from Thásos. Bristowe's (1935) review of the Greek spiders included records of the 373 taxa reported at the time but it is evident that most studies had concentrated on the Ionian islands and there is a noticeable lack of information from the Aegean. The Greek list has since grown to 642 species (Deltshev 1999), which is comparable to that of Britain, but as there are more than 1,400 species known from Italy it seems that there are plenty of discoveries still to be made. A new review of the Greek spider fauna has recently been published (Bosmans & Chtazaki 2005) but I have not been able to get hold of a copy yet to see what information it has on Thásos.

Three conspicuous species that are present on the island deserve mention. The highly attractive red and black males of the  jumping spider Philaeus chrysops can be seen in open stony habitats from  the coast to the mountain tops, although the less conspicuous female is not so easily seen. It is also unusual to see the tarantula Geolycosa vultuosa above ground, but its turreted burrows are not uncommon in bare friable soils alongside roads and tracks in the middle of the island. This is one of the largest European wolf spiders and its bite is said to be poisonous, although whether this is true is unclear.  The beautiful ladybird spider Eresus sp. appears to be quite localised on Thásos and I have only found it at Cap Prinos. The exquisite males wander actively across sandy ground in early June but the all-black females rarely stray from their burrows, where they live all year round. In addition to these three I have recorded a further fourteen spider species on the island (Evarcha arcuata, E. jucunda, Heliophanus equester, H. kochi, H. melinus, H. tribulosus, Leptorchestes cf. berolinensis, Marpissa nivoyi, Myrmarachne formicaria, Pellenes moreana, Salticus zebraneus, Siatis taurica, Heriaeus hirtus and Pholcus phalangioides) and I am grateful to Richard Gallon and Dmitri Logunov for the identification of all but the last two of these species. [note: two Eresus species are reported from Greece according to Fauna Europaea - cinnabarinus and walckenaeria - though Eresus taxonomy is complicated and unresolved. At present it is not certain which taxon occurs on Thásos]

The scorpion 'Euscorpius' is widespread and not uncommon  under logs and stones in old olive groves and  woodland habitats around the lowland fringe of the island. I have also seen Euscorpius at 850 metres asl on montane scree (see image) and this may be a different species. Euscorpius are harmless to Man but Mesobuthus (yellowish with longer, narrower pincers) may also occur on the island and its sting is painful and potentially dangerous to infants. Werner (1938) reported that he was unable to find Mesobuthus on any of the Thracian islands (Thásos, Samnothraki, Limnos) so it may genuinely be absent. According to Fet & Braunwalder (2000) four scorpion species have been found in Greece. The taxonomy of Euscorpius in eastern Europe is currently the subject of much research (Fet et al 2003) and the common scorpion from Greece is currently referred to E. sicanus. However, it appears that there is another Euscorpius species in north-eastern Greece (including Thásos) that represents an undescribed taxon. More information on this issue is available on The Scorpion Files website.  

 Pseudoscorpions are miniature, only 3millimetres or so long, but fearsome predators of tiny invertebrates. It is claimed that "the Balkan peninsula has the greatest diversity of pseudoscorpions in the world" (Curcic 1986), principally due to the high  number of endemics in cave systems along the Adriatic coast. It seems unlikely, however, that the fauna is particularly diverse on Thásos, but two taxa (det. Dr Gerald Legg) appear to be quite common on the island. Dactylochelifer gracilis is widespread in coastal garigue and other shrubby vegetation where it hunts along twigs and branches above ground level, whilst a species of Neobisium (either sylvaticum or hellenum) can be found by sieving grassland litter in lowland meadows. I have no information on the harvestmen (Opiliones) or other related groups on the island. I have taken a large Anelasmocephalus from limestone pavement at 850m asl but have not been able to identify this species yet.

This inadequate account of the arachnids of Thásos emphasises how much there is still to be learnt about the island's invertebrates. Difficulties in the identification of specimens are no doubt the major reason for the paucity of information but with the appearance of guides such as that by Metzner (1999) there is hope that a greater understanding of the island's arachnid fauna will be possible in the future. There is plenty of scope here to make a significant contribution to knowledge of the island's fauna. 

REFERENCES

Bristowe, W.S. 1934. The spiders of Greece and the adjacent islands. Proceedings of the Zoological Society of London, pp: 733-788.

Curcic, B.P.M. 1987. On the origin and biogeography of some pseudoscorpions of the Balkan Peninsula. Biologia Gallo-Hellenica, 12: 85-92.

Deltshev, C. 1999. A faunistic and zoogeographical review of the spiders (Araneae) of the Balkan peninsula. Journal of Arachnology, 27: 255-261.

Fet, V. & Braunwalder, M.E. 2000. The scorpions (Arachnida: Scorpiones) of the Aegean area: current problems in taxonomy and biogeography. Belgian Journal of Zoology, 130 (Supplement): 17-22.

Fet, V. et al. 2003. New molecular and morphological data on the "Euscorpius carpathicus" species complex (Scorpiones: Euscorpiidae) from Italy, Malta and Greece justify the elevation of E.c. sicanus (C.L. Koch, 1837) to the species level. Revue Suisse de Zoologie, 110: 355-379.

Metzner, H. 1999. Die Springspinnen (Araneae, Salticidae) Griechenlands. Andrias, 14: 3-279.

Thaler, K., Buchar, J. & Knoflach, B. 2000. Notes on wolf spiders from Greece (Araneae, Lycosidae). Linzer Biologische Beitraege, 32: 1071-1091.

Werner, F. 1938. Ergebnisse der achten zoologischen Forschungsreise nach Griechenland. SB. Akad. Wiss Wien, Mathen-naturw. Kl.,147: 151-173.