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_____________________________________________________________________ NON-MARINE MOLLUSCA
The first survey of terrestrial molluscs on Thásos appears to be that of Boettger (1907) and this was extended by Urbanski (1960) to give a list of 22 species for the island. Meanwhile, Angelov (1959) investigated the freshwater Mollusca in 1942. There was an attempt twenty years ago (Butot & Subai, 1981) to establish, in conjunction with the European Invertebrate Survey, a Working Group for conchologists studying Greek molluscs. W.H. Neuteboom of the Netherlands was listed as having collected on Thásos. He did not publish his results but amongst his records are three species that have not been found by other conchologists working on Thásos (Reischütz 1988). In 1982 Reischütz (1983), in a major study of the island's fauna, sampled a range of habitats across the island and recorded 46 taxa, including a species new to science (Vitrea thasia) and two new sub-species. Riedel (1988) reviewed the status of the genus Balcanodiscus in the Balkans, raising one of Reischütz’s sub-species (Balcanodiscus frivaldskyanus carinatus) to specific status and identifying B. difficilis as new to science from Thásos. Three further species are reported by Bank & Menkhorst (1992), including Zebrina (Rhabdoena) mirifica which is described new to science from the Ipsarion range above Theologos. Most recently, Sylvia van Leeuwen added two more terrestrial snail species, Xerotricha apicina and Monacha claustralis, to the island list during a visit in May 2004 (van Leeuwen 2005). Monacha cartusiana had previously been reported from Thasos (Boetger 1907, Urbanski 1960, Reischütz 1983) but the taxonomy of the cartusiana aggregate is complex and, on biogeographic grounds, it is likely that all previous records refer to claustralis. I am grateful to P.L. Reischütz for providing me with additional information and an updated checklist for the mollusc fauna of Thásos. My own casual collecting has so far added eight species to the island list, Cochlicella barbara (det. I.J. Killeen), which appears to be widespread in lowland sandy grasslands, Truncatella subcylindrica and Pupilla triplicata (det. I.J. Killeen, conf. P.L. Reischütz), Vertigo angustior (det. P.L. Reischütz), V. pygmaea and V. moulinsiana (conf. I.J. Killeen), Phenacolimax annularis (det P.L. Reischütz), and Carychium tridentatum. However, Urbanski (1960) reported C. acuta (Müller) from the island and hence barbara has probably been recorded, but misidentified, previously. The discovery of three Vertigo species in a fen outside Thassos Town (Fowles 2002) is remarkable. V. moulinsiana is new to Greece, whilst both angustior and moulinsiana are rare and declining throughout Europe and are included on the EC Habitats & Species Directive (Annex II). V. angustior is otherwise known in Greece only from shells of uncertain age found in debris by a spring on the eastern margin of the Pangaion by P.L. Reischütz in August 1982. To date, sixty-nine non-marine mollusc species (61 terrestrial snails plus three slugs and five aquatic snails) have been recorded from Thásos. Excluding Crete (twenty-four times the size of Thásos and with many endemics amongst its 132 species), the maximum recorded number of terrestrial snail species reported by Welter-Schultes & Williams (1999) from any of the Aegean islands was sixty from Rhodes and fifty-two from Lésvos. A visit by Prof D. Georgiev in August 2020 added a further five species to the island list - Aegopinella minor, Carychium minimum, Deroceras thersites, Limax graecus and the freshwater clam Pisidium personatum (Georgiev 2020). He comments that this brings the total number of species known from Thásos up to 83 and it would appear that another nine additions to the island's molluscan fauna have been reported by Frank (2018), although I have not managed to see this paper as yet. The Hellenic Zoological Society has published a comprehensive treatment of the Zonitidae (s.l.) of Greece, as part of the major series Fauna Graeciae (Riedel 1992). Amongst this group, only eleven of the 116 species known from Greece occur on Thásos but they include the endemic troglophile Balcanodiscus difficilis (which is recorded from just two caves on the island), its near-endemic congener B. carinatus (also recorded from a few localities on the adjacent mainland), and Vitrea thasia, which has been reliably recorded only from Thásos but material collected from eastern Macedonia probably also belongs to this species. The latest addition to this excellent series is Wiktor's (2001) account of the slugs of Greece.
CHECKLIST OF TERRESTRIAL & FRESHWATER MOLLUSCA Theodoxus fluviatilis (L.) Pomatias elegans (O.F. Müller) Carychium minimum O. F. Müller Carychium tridentatum (Risso) Bythinella charpentieri (Roth) Belgrandiella hohenackeri (Küster) Ovatella myosotis (Draparnaud) Galba truncatula (O.F. Müller) Ancylus fluviatilis O.F. Müller Pisidium personatum Malm Pyramidula rupestris (Draparnaud) agg. Truncatella subcylindrica (L.) (fa. costulata Rossi) Truncatellina rothi (Reinhardt) Vertigo angustior Jeffreys Vertigo moulinsiana (Dupuy) Vertigo pygmaea (Draparnaud) Sphyradium doliolum (Letourneux) Granopupa granum (Draparnaud) Rupestrella rhodia (Roth) Lauria cylindracea (Da Costa) Pupilla triplicata (Studer) Acanthinula aculeata (O.F. Müller) Mastus athensis jaczewskii (A. J. Wagner) Merdigera (=Ena) obscura (O. F. Müller) Imparietula seductilis (Rossmässler) Zebrina detrita (O.F. Müller) Zebrina (Rhabdoena) mirifica Bank & Menkhorst Chondrula microtraga (Rossmässler) Punctum pygmaeum (Draparnaud) Paralaoma servilis (Shuttleworth) Phenacolimax annularis (Studer) Aegopinella minor (Stabile, 1864) Vitrea contracta (Westerlund) Vitrea neglecta Damjanov & Pinter Vitrea thasia Riedel & Reischütz Balcanodiscus carinatus Reischütz Balcanodiscus difficilis Riedel Oxychilus hydatinus (Rossmässler) Oxychilus inopinatus (Uli…ný) Oxychilus glaber (Rossmässler) Oxychilus depressus (Sterki) Daudebardia rufa (Draparnaud) Daudebardia brevipes (Draparnaud) Deroceras cf. andrios (Simroth) Deroceras (Agriolimax) thersites (Simroth) Limax (Limax) graecus (Simroth) Cecilioides acicula (O.F. Müller) Macedonica thasia Nordsieck Carinigera buresi insularis (Urbanski) Balea biplicata (Montagu) Bulgarica denticulata thessalonica (Rossmässler) Tandonia sowerbyi (Férussac) Tandonia kusceri (J. Wagner) Cernuella virgata (Da Costa) Xeropicta krynickii (Krynicki) Xerolenta obvia obvia (Menke) and Xerolenta obvia pappi (Schütt) Xerolenta thasia (Reischütz) Helicella conspurcata (Draparnaud) Xerotricha apicina (Lamarck) Trochoidea pyramidata (Draparnaud) Cochlicella barbara (L.) Monacha claustralis (Menke) Metafruticicola redtenbacheri (L. Pfeiffer) Euomphalia strigella (Draparnaud) Lindholmiola regisborisi (A. J. Wagner) Lindholmiola reischützi (Falkner) Lindholmiola corcyrensis (Férussac) Chilostoma (Thiessea) valkanovi (Urbanski) Chilostoma (Faustina) rumelica (Rossmässler) Eobania vermiculata (O. F. Müller) Cornu (=Helix) aspersum (O.F. Müller) Helix philibinensis Rossmässler Helix figulina Rossmässler Euglesa casertana (Poli)
[Angelov (1950) reported Bythinella alta Clessin and Lithoglyphoides virescens Küster from Thásos, but these are considered to represent mis-identifications of Bythinella charpentieri and Belgrandiella hohenackeri respectively (P.L. Reischütz, pers. comm.). Cochlicella acuta (L.), reported by Urbanski (1960), has been omitted from this checklist as it seems likely that this represents a mis-identification of Cochlicella barbara. Reischütz (1988) has corrected the identification (Reischütz, 1983) of Mastus rossmaessleri to M. athensis jaczewski, whilst Helicella rhabdotoidea thasia is now referred to Xerolenta thasia (P.L. Reischütz, pers. comm.). It should also be noted that Lindholmiola lens insularis, reported by several authors, is now regarded as a good species, Lindholmiola reischützi Falkner 1995.] REFERENCES Angelov, A. 1959. Beitrag zur erforschung der Süsswassermalakofauna der Insel Thasos und der Agäischen Küste. Izv. zool. Inst. Sof., 8: 297-299. Bank, R.A.& Menkhorst, H.P.M.G. 1992. Notizen zur Familie der Enidae, 4. Revision der griechischen Arten der Gattungen Ena, Zebrina, Napaeopsis und Turanea (Gastropoda Pulmonata: Pupilloidea). Basteria 56: 105-158. Boettger, O. 1907. Die ersten Landschnecken von der Insel Thasos. Nachrichtsbl. deutsch. malak. Ges., 39: 34-40. Butot, L.J.M. & Subai, P. 1981. A Working Group on Greek molluscs. Conchologists’ Newsletter, 78: 335-337. Fowles, AP. 2002. Vertigo angustior Jeffreys, 1830 and Vertigo moulinsiana (Dupuy, 1849), new to Greece, on the Aegean island of Thásos. Journal of Conchology, 37: 683-684. Frank, C. 2018. Ein weiterer Beitrag zur Kenntnis der Molluskenfauna der Insel Thasos (nördliche Ägäis, Griechenland. Nachrichtenblatt der ersten Vorarlberger malakologischen Gesellschaft, 25: 69-78. Georgiev, D. 2020. New records of non marine molluscs from Thassos Island (North Aegean, Greece). ZooNotes, 165: 1-3. Leeuwen, S. van. 2005. Shelpen verzamelen op Thasos, Griekenland. De Kreukel, 41: 3-6. Mylonas, M. 1984. The influence of Man: a special problem in the study of the zoogeography of terrestrial molluscs on the Aegean islands. In: World-wide snails: biogeographical studies on non-marine Mollusca. Eds. A. Solem & A.C. van Bruggen, pp. 249-259. Leiden, E.J. Brill/Dr W. Backhuys. Reischütz, P. L. 1983. Ein Beitrag zur Molluskenfauna der Insel Thasos (Griechenland). Annalen Des Naturhistorischen Museums In Wien, 85 (Serie B Botanik Und Zoologie): 133-146. Reischütz, P.L. 1988. Beiträge zur Molluskenfauna Thrakiens und Ostmakedoniens, II. Annalen Des Naturhistorischen Museums In Wien, 90 (Serie B Botanik Und Zoologie): 341-356. Riedel, A. 1988. Zur Kenntnis der Gattung Balcanodiscus, 2 (Gastropoda, Stylommatophora, Zonitidae). Malakologische Abhandlungen, 13: 93-104. Riedel, A. 1992. The Zonitidae (sensu lato) (Gastropoda, Pulmonata) of Greece. Fauna Graeciae, Volume 5. Urbanski, J. 1960. Bemerkenswerte balkanische Stylommatophoren (Systematische, zoogeographische und ökologische Studien über die Mollusken der Balkanhalb - insel II.). Ein Beitrag zur Kenntnis der Molluskenfauna der Insel Thasos und des mazedonisch-thrazischen Küstenlandes. Izvest. Zool. Inst. Sofia, 9: 71-105. Welter-Schultes, F. & Williams, M.R. 1999. History, island area and habitat availability determine land snail species richness of Aegean islands. Journal of Biogeography, 26: 239-249. Wiktor, A. 2001. The slugs of Greece (Arionidae, Milacidae, Limacidae, Agriolimacidae - Gastropoda Stylommatophora). Fauna Graeciae, Volume 8.
Carinigera buresi (Thassos Valley) |
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Mylonas (1984) provides an interesting account of the non-marine Mollusca of
the Aegean islands (although Thásos is not included), in which he highlights
the changes brought about in the composition of island snail faunas by Man’s
activities. From his work it would appear that the larger islands support about
40 different species, amongst which synanthropic species may contribute about
one-third of the fauna. His findings are reinforced by Welter-Schultes &
Williams (1999) in their study of the factors influencing mollusc faunas on
sixty-five Aegean islands (though, again, not including Thásos). It can be
anticipated that the snail fauna on Thásos will be amongst the largest of the
Aegean islands because of its size, range of habitats, and closeness to the
Greek mainland. Endemics are frequent on many of the Aegean islands and in some cases
may comprise up to 50% of the total fauna. However, the Thásos fauna is similar to that
found on the island of Samothraki in that both islands have a strong representation
of eastern Balkan species and few Aegean elements.