The non-marine molluscs of the country of Turkey are a part of the molluscan fauna of Turkey. The biodiversity of non-marine molluscs of Turkey is richer than in surrounding European states. There are at least 825 species of non-marine molluscs living in the wild in Turkey. An approximate guess to the total number, however, is of about 1030 non-marine molluscs in Turkey (see the table below). There are a total of 825 species of gastropods, which breaks down to 95 (counted 80 "Prosobranchia" only and at least 15 other freshwater snails from this list) taxa of freshwater gastropods (including brackish water species), and 730 species (and subspecies) of land gastropods. There is also relevant number of freshwater bivalves living in the wild in Turkey. According to Gümüş et al. (2009), the Turkish malacofauna of land gastropods currently comprises 730 valid species and subspecies of terrestrial snails, belonging to 36 families. Gümüş et al. (2009) stated that Turkey has a very rich freshwater malacofauna with a very large proportion of endemic species. Those authors estimated that Turkey is inhabited by at least 300 species of freshwater molluscs. There are also significant numbers of non-indigenous species, including bivalves and various synanthropic gastropods and bivalves.

Land gastropods overview

A country such as Turkey, with a highly variable relief and a diversified climate and vegetation, can support a similarly rich and diversified malacofauna of terrestrial gastropods. Consequently, the recent changes in both land use and climate (which is gradually shifting from semi-arid and winter-cold Central Turkey to a subtropical periphery with high humidity during winter) have immediately affected the malacofauna, causing area shifts following the unstable environmental conditions, including depletion or even complete loss of some populations. Increasing pasture farming leads to a loss of forest vegetation, and thus to a loss of those molluscan species which are adapted to such conditions. The recent rise of average summer temperature resulting from global warming may particularly affect the Mediterranean species. Gümüş et al. (2009) speculated that both the average length of the dry summer period and the absolute temperature are rising, and that the aestivation period of species adapted to the Mediterranean drought is now too long. The animals die from starvation or desiccation, and several species or subspecies may already be approaching the verge of extinction. As far as nomenclature, an average of two to three additional synonym names for each taxon are available to land gastropods in Turkey. The degree of endemism for the area of Turkey is about 65%. The degree of endemism on the species level is relatively high and is comparable to that of Greece, which houses the highest number of terrestrial snail taxa in Europe, with a similarly high value of endemism. In Turkey, several pulmonate families reach a maximum of biodiversity. The biodiversity has been able to develop there without any major interruptions since the Pliocene. The malacofauna of some areas, such as the inner Anatolian steppe areas, and many of the densely forested mountain ranges, is incompletely ascertained or almost completely unknown. As research progresses, records of species new to science can be expected, and the knowledge of the ranges of already-known taxa will increase. Another accretion in taxa numbers may be caused by the resolution of cryptic species clusters with the help of DNA sequencing methods, the Barcoding Project, and other related activities.

History of malacozoology of terrestrial gastropods

The first species from the Turkish terrestrial malacofauna were described by Guillaume-Antoine Olivier (1756–1814), who, amongst others, collected natural history objects in the Middle East. For example he named the following species: Multidentula ovularis (Olivier, 1801) and Bulgarica denticulata (Olivier, 1801) from "Ghemlek" (= Gemlik in the Bay of Mudanya) or Assyriella guttata (Olivier, 1804) from Urfa. After Olivier, the area was visited by the German Johannes Rudolf Roth and his party, and then was target of other scientists, naturalists and collectors like Bellardi, Boissier, Dubois de Montpereux, Frivaldsky, Huet de Pavillon, Parreyss, Schläfli, Sievers and others. Their collections went to the most prolific malacologists interested in the area like Jules René Bourguignat, Jean de Charpentier, Heinrich Carl Küster, Johann Rudolf Albert Mousson, Ludwig Karl Georg Pfeiffer and Emil Adolf Rossmässler. In the second half of the 19th century, the famous German malacologists Oskar Boettger and Wilhelm Kobelt from the Senckenberg Museum in Frankfurt intensified the malacological research in Turkey, with contributions by Gottfried Nägele, Otto von Retowski and Carl Agardh Westerlund. After Kobelt’s death in 1916, the "Golden Age" of malacology was finished except for some contributions by Paul Hesse, Wassili Adolfovitch Lindholm and Otto W. von Rosen. After almost 50 years of scientific silence, it was the "Netherlands biological expedition to Turkey 1959", which again shifted the focus of malacologists to Turkey. Since then, the malacological science received an enormous boost and stimulated both international as well as Turkish scientists to deepen the knowledge of the Turkish malacofauna. During this period, which now lasts about 50 years, one third of the number of taxa accepted today as valid has been added! Some of the most active contributors to this success should be mentioned here (in alphabetic order of the surnames): R. A. Bank; G. Falkner; L. Forcart; E. Gittenberger; Z. P. Erőss; Z. Fehér; B. A. Gümüş; B. Hausdorf; V. Hudec; H.P.M.G. Menkhorst; L. Németh; E. Neubert; H. Nordsieck; B. Páll-Gergely; W. Rähle; A. Riedel; H. Schütt; R. Şeşen; M.I. Szekeres; A. Wiktor and M. Z. Yıldırım.

Freshwater gastropods

Neritidae Viviparidae Thiaridae Melanopsidae Bithyniidae Hydrobiidae Lithoglyphidae Bythinellidae Assimineidae Valvatidae (All species above this line are freshwater "Prosobranchia".) Cochliopidae Physidae Planorbidae Lymnaeidae Ellobiidae

Land gastropods

Ellobiidae Truncatellidae Succineidae Pyramidulidae Clausiliidae Ferussaciidae Achatinidae Pupillidae Lauriidae Orculidae Chondrinidae Pleurodiscidae Truncatellinidae Valloniidae Enidae Punctidae Arionidae Oxychilidae Pristilomatidae Zonitidae Trigonochlamydidae Milacidae Limacidae Agriolimacidae Helicodontidae Geomitridae Hygromiidae Helicidae Trissexodontidae

Bivalves

Unionidae Sphaeriidae Dreissenidae