Theodoxus is a genus of nerites, small water snails with an operculum, some of which live in freshwater, and some in both freshwater and brackish water, aquatic gastropod mollusks in the family Neritidae, the nerites.Bouchet, P. (2014). Theodoxus Montfort, 1810. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=153531 on 2014-11-17.
Distribution The distribution of the genus Theodoxus includes Europe and northern Africa and also extends east to southern Iran. No other species within Neritidae have sympatrical distribution with Theodoxus. The distribution of the genus Theodoxus is an exception within Neritidae, because Neritidae live primarily in the southern hemisphere. Species within Theodoxus are the only Neritidae snails, that live in temperate climate.
Bunje & Lindberg (2007) presented the first phylogenetic hypothesis of the clade Theodoxus.Bunje P. M. & Lindberg D. R. (2007). "Lineage divergence of a freshwater snail clade associated with post-Tethys marine basin development". Molecular Phylogenetics and Evolution 42(2): 373–387. . The evolution of the genus Theodoxus was affected by separating of Mediterranean Sea and Paratethys sea in Miocene.
Description
The shell in this genus is semiovular with a flat apertural plain. There is no umbilicus. The columella and inner whorls are dissolved.
Species in the genus Theodoxus are highly variable in size, in color pattern of the periostracum, in details of the operculum and in the radula, and all these factors can make identification to species level very challenging.Zettler M. L., Frankowski J., Bochert R. & Röhner M. (2004). "Morphological and ecological features of Theodoxus fluviatilis (Linnaeus, 1758) from Baltic brackish water and German freshwater populations". Journal of Conchology 38(3): 305-316. .pdf PDF.
Ecology These animals live on stones, and often also under stones, in up to 5–6 m depth or deeper, feeding on algal covers. Theodoxus needs rough surfaces in order to be able to digest its food, so a stony substrate is necessary. Green algae are not consumed; Theodoxus has no cellulases. These snails lay egg capsules containing 30–70 eggs each, usually on the shells of other Theodoxus animals; only one juvenile grows, the other eggs serve as food.
Species There were no systematic review of the genus Theodoxus as of 2007. Bunje (2004) noted at least 34 extant taxa at species level in the genus Theodoxus. IUCN Red List (2015) provided conservation status for 23 species of Theodoxus.The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 23 March 2015. (Searching for "Theodoxus".)
Species within the genus Theodoxus include: Subgenus Brusinaella Andrusov, 1912Andrussov (1912). Verh. Russ. min. Ges. St. Pétersburg (2)49: 4 † Theodoxus petasatus (Seninski, 1905) Subgenus Calvertia Bourguignat, 1880Bourguignat (1880). Etude Foss. Tert. Quat. Vallée Cettina, page 44.
† Theodoxus acuticarinatus (Fuchs, 1870) † Theodoxus amblygonioides Wenz, 1930 † Theodoxus amethystinus (Brusina, 1874) † Theodoxus anconae (Capellini, 1880) † Theodoxus angularis Gozhik, 2002 † Theodoxus anonymus Anistratenko & Gozhik, 1995 † Theodoxus atticus Kühn, 1963 † Theodoxus barakovici (Brusina, 1902) † Theodoxus bessarabicus (Sinzov, 1896) † Theodoxus brusinai (Pavlović, 1931) † Theodoxus capellinii (Pantanelli, 1876) † Theodoxus capillaceus (Brusina, 1874) † Theodoxus crescens (Fuchs, 1870) † Theodoxus doderleini (d'Ancona, 1869) † Theodoxus dumortieri (Fontannes, 1878) † Theodoxus fasciatus Gozhik in Gozhik & Datsenko, 2007 † Theodoxus gnezdai (Brusina, 1884) † Theodoxus grateloupianus (Férussac, 1823) † Theodoxus hoernesanus (Semper, 1867) † Theodoxus ingulenzis Gozhik in Gozhik & Datsenko, 2007 † Theodoxus kalodictya (Andrusov, 1909) † Theodoxus koslinskyi (Porumbaru, 1881) † Theodoxus lamellatus (Brusina, 1892) † Theodoxus lineatus (Sinzov, 1896) † Theodoxus lorkovici (Brusina, 1878) † Theodoxus macedonicus Wenz, 1943 † Theodoxus maculosus Gozhik in Gozhik & Datsenko, 2007 † Theodoxus mayeri (Semper, 1867) † Theodoxus militaris (Neumayr, 1869) † Theodoxus miljkovici (Brusina, 1902) † Theodoxus millepunctatus (Brusina, 1902) † Theodoxus moeschi Locard, 1893 † Theodoxus morulus Kühn, 1963 † Theodoxus mutinensis (d'Ancona, 1869) † Theodoxus neumayri (Burgerstein, 1877) † Theodoxus nitens Gozhik, 2002 † Theodoxus nivosus (Brusina, 1874) † Theodoxus novorossicus (Sinzov, 1896) † Theodoxus obtusangulaeformis Gozhik, 2002 † Theodoxus oxytropida (Andrusov, 1909) † Theodoxus pavlovici Milošević, 1983 † Theodoxus philippianus Locard, 1883 † Theodoxus pilari (Brusina, 1884) † Theodoxus platystoma (Brusina, 1874) † Theodoxus pseudodanubialis (Sinzov, 1896) † Theodoxus pseudofluviatilis Locard, 1893 † Theodoxus pseudograteloupanus (Sinzov, 1884) † Theodoxus radmanesti (Fuchs, 1870) † Theodoxus radovanovici (Brusina, 1893) † Theodoxus reiseri (Brusina, 1902) † Theodoxus rugosus (Pavlović, 1931) † Theodoxus sagittiferus (Brusina, 1874) † Theodoxus schachmaticus (Andrusov, 1909) † Theodoxus scoliogramma (Brusina, 1884) † Theodoxus semidentatus (Sandberger, 1875) † Theodoxus serrulatus (Brusina, 1892) † Theodoxus slavonicus (Brusina, 1878) † Theodoxus sophievkaensis Gozhik in Gozhik & Datsenko, 2007 † Theodoxus stanae (Brusina, 1893) † Theodoxus stefanescui (Fontannes, 1887) † Theodoxus stefanescuiformis Gozhik in Gozhik & Datsenko, 2007 † Theodoxus subquadrofasciatus Gozhik, 2002 † Theodoxus subslavonicus Gozhik, 2002 † Theodoxus sundicus (Andrusov, 1909) † Theodoxus suskalovici (Pavlović, 1903) † Theodoxus sycophantus (Brusina, 1878) † Theodoxus tropidophorus (Brusina, 1884) † Theodoxus turbinatus (Fuchs, 1870) † Theodoxus veljetinensis (Pavlović, 1903) † Theodoxus venustus (Brusina, 1897) † Theodoxus xanthozona (Brusina, 1884) † Theodoxus zagradovkaensis Gozhik, 2002 † Theodoxus zivkovici (Pavlović, 1903)
Subgenus Neritonyx Andrusov, 1912Andrussov (1912). Verh. Russ. min. Ges. St. Pétersburg (2)49: page 4 (Brusinaella) and page 1 (Neritonyx). † Theodoxus unguiculatus (Seninski, 1905)
Subgenus Ninniopsis Tomlin, 1930Tomlin J. R. le B. (1930). "Some preoccupied generic names.—II". Proceedings of the Malacological Society of London 19(1): 22-24, page 24. † Theodoxus colchicus (Andrusov, 1912)
Subgenus Neritaea Roth, 1855Roth (1855). Malak. Bl. 2: 56. Theodoxus anatolicus (Récluz, 1841)"Neritaea". Fauna Europaea, last update 27 January 2011, accessed 12 April 2011. † Theodoxus groyanus (Férussac, 1823) Theodoxus jordani (G. B. Sowerby I, 1836) † Theodoxus micans (Gaudry & Fischer in Gaudry, 1867) Theodoxus niloticus (Reeve, 1856) - synonym: Theodoxus africanus (Reeve, 1856) † Theodoxus subdoricus Schütt, 1976 Theodoxus subterrelictus Schütt, 1963 Theodoxus peloponensis (Récluz, 1841) Theodoxus varius (Menke, 1828)
Subgenus Theodoxus Montfort, 1810
Theodoxus altenai Schütt, 1965"Species in genus Theodoxus " (n=20). AnimalBase, accessed 11 April 2011. Schütt H. (1965). "Zur Systematik und Ökologie türkischer Süßwasserprosobranchier". Zoologische Mededelingen 41(3): 43-72, Plate 1. abstract, PDF. Theodoxus baeticus (Lamarck, 1822)"Theodoxus ". Fauna Europaea, last update 27 January 2011, accessed 12 April 2011. † Theodoxus becenensis (Cobălcescu, 1883) † Theodoxus brenneri (Handmann, 1882) † Theodoxus carasiensis Jekelius, 1944 † Theodoxus constantiae Stefanescu, 1896 † Theodoxus culceri (Porumbaru, 1881) † Theodoxus cyrtocelis (Krauss, 1852) Theodoxus danubialis (Pfeiffer, 1828) † Theodoxus denisluensis (Oppenheim, 1919) † Theodoxus deperditus (Almera, 1894) † Theodoxus elongatulus (Philippi, 1844) † Theodoxus eugenii Jekelius, 1944 Theodoxus euxinus (Clessin, 1886) Theodoxus fluviatilis (Linnaeus, 1758) - type species.Anistratenko V. V. (2005). "Lectotypes for Tricolia pullus, Gibbula divaricata and Theodoxus fluviatilis (Mollusca, Gastropoda) revisited". Vestnik zoologii 39(6): 3-10. PDF . synonyms: Theodoxus brauneri (Lindholm, 1908) (but as separate species per); Theodoxus brauneri f. lacrymans Lindholm, 1908; Theodoxus brauneri f. alboguttata Lindholm, 1908; Theodoxus brauneri f. pulherrima Lindholm, 1908; Theodoxus lutetianus Montfort, 1810. Bunje (2005) PDF. does not consider Theodoxus velox Anistratenko, 1999Anistratenko O. Y., Starobogatov Y. I. & Anistratenko V. V. (1999). "Mollusks of the genus Theodoxus (Gastropoda, Pectinibranchia, Neritidae) from the Black and the Azov seas basin". Vestnik Zoologii 33: 11-19. to be a distinct species from Theodoxus fluviatilis. † Theodoxus gregarius (Thomä, 1845) Theodoxus heldreichi (Martens, 1879) † Theodoxus hisingeri (Bellardi & Michelotti, 1841) Theodoxus hispalensis (Martens, 1879) † Theodoxus jekeliusi Jurišić-Polšak, 1979 † Theodoxus leobersdorfensis (Handmann, 1887) Theodoxus meridionalis (Philippi, 1836) † Theodoxus milessii Papp, 1979 † Theodoxus moosbrunnensis Papp, 1953 † Theodoxus morellii (Bellardi & Michelotti, 1841) Theodoxus pallasi Lindholm, 1924 - synonym: Theodoxus lituratus (Eichwald, 1838) † Theodoxus pilidei (Tournouër, 1879) Theodoxus prevostianus (Pfeiffer, 1828) † Theodoxus punctatolineatus (Sinzov, 1896) Theodoxus saulcyi (Bourguignat, 1852) † Theodoxus scamandrius (Calvert & Neumayr, 1880) † Theodoxus semiplicatus (Neumayr in Herbich & Neumayr, 1875) † Theodoxus simplex (Fuchs, 1877) † Theodoxus subglobosus (Eichwald, 1853) Theodoxus subthermalis (Bourguignat in Issel, 1865) or Theodoxus fluviatilis subthermalis Issel, 1865 Theodoxus transversalis (Pfeiffer, 1828) † Theodoxus trifasciatus (Grateloup, 1839) † Theodoxus turislavicus Jekelius, 1944 Theodoxus valentinus (Graells, 1846) † Theodoxus zografi (Brusina, 1902)
Subgenus ?
† Theodoxus abnormis (Jenkins, 1864) † Theodoxus almelae (Revilla, 1958) Theodoxus astrachanicus Starobogatov, 1994 † Theodoxus banaticus Jekelius, 1944 † Theodoxus bohotinensis (Simionescu & Barbu, 1940) † Theodoxus bolivari (Royo Gómez, 1922) † Theodoxus bukowskii (Oppenheim, 1919) Theodoxus cariosus (Wood, 1828) Theodoxus coronatus (Leach, 1815)WoRMS (2010). Theodoxus coronatus (Leach, 1815). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=216264 on 2011-04-11 † Theodoxus crenulatus (Klein, 1853) † Theodoxus cunici (Brusina, 1892) Theodoxus danasteri (Lindholm, 1908) † Theodoxus doricus (Neumayr, 1880) Theodoxus euxinus (Clessin, 1886) Theodoxus gloeri Odabaşi & Arslan, 2015 Theodoxus gurur Sands & Glöer, 2020 † Theodoxus hellenicus (Bukowski, 1896) † Theodoxus imbricatus (Brusina, 1878) † Theodoxus intracarpaticus Jekelius, 1944 † Theodoxus licherdopoli (Stefanescu, 1896) Theodoxus luteofasciatus (Miller, 1879) Theodoxus macri (Sowerby, 1849) Theodoxus maresi (Bourguignat, 1864) Theodoxus marteli (Pallary, 1920) Theodoxus milachevitchi Golikov & Starobogatov, 1966 † Theodoxus mutinensis (d'Ancona, 1869) Theodoxus numidicus (Récluz, 1841) Theodoxus pallasi Lindholm, 1924 Theodoxus pallidus Dunker, 1861 † Theodoxus pappi Sauerzopf, 1952 † Theodoxus paradisii (Magrograssi, 1928) † Theodoxus patrae Esu & Girotti, 2015 † Theodoxus percarinatus (Oppenheim, 1919) Theodoxus pilidei (Tournouêr, 1879) † Theodoxus politioanei Jekelius, 1944 † Theodoxus politus Jekelius, 1944 Theodoxus poppei Ahuir, 2020 † Theodoxus postcrenulatus Papp, 1953 † Theodoxus prozlatarici Jekelius, 1944 † Theodoxus pseudodacicus Neubauer, Harzhauser, Georgopoulou, Mandic & Kroh, 2014 † Theodoxus quadrifasciatus (Bielz, 1864)
† Theodoxus reticulatus Pană, 1990 † Theodoxus rhodiensis (Tournouër in Fischer, 1877) Theodoxus sarmaticus (Lindholm, 1901)