Theodoxus fluviatilis

Theodoxus fluviatilis
An oblique left side view of a live Theodoxus fluviatilis
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Neritimorpha clade Cycloneritimorpha
Superfamily:	Neritoidea
Family:	Neritidae
Subfamily:	Neritininae
Tribe:	Theodoxini
Genus:	Theodoxus
Subgenus:	Theodoxus
Species:	T. fluviatilis
Binomial name
Theodoxus fluviatilis (Linnaeus, 1758)
Synonyms
Nerita fluviatilis Linnaeus, 1758 Neritina fluviatilis (Linnaeus, 1758) Theodoxus lutetianus Montfort, 1810 (unnecessary substitute name for Nerita fluviatilis Linnaeus, 1758) Theodoxus balticus (Nilsson, 1821) Theodoxus halophilus (Klett, 1828) Theodoxus trifasciatus (Menke, 1828) Theodoxus rhodocolpa De Cristofori & Jan, 1832 Theodoxus thermalis (Boubée, 1833) Theodoxus intextus A. & J. B. Villa, 1841 Theodoxus parreyssii A. & J. B. Villa, 1841 Theodoxus ticinensis A. & J. B. Villa, 1841 Theodoxus zebrina Récluz, 1841 Theodoxus mittreana Récluz, 1842 Theodoxus doriae Issel, 1865 Theodoxus reynesiana Dubreuil, 1869 Theodoxus brauneri Lindholm, 1908 – or as separate species Theodoxus brauneri f. lacrymans Lindholm, 1908 Theodoxus brauneri f. alboguttata Lindholm, 1908 Theodoxus brauneri f. pulherrima Lindholm, 1908 Theodoxus dniestroviensis Put, 1972 Theodoxus velox Anistratenko, 1999

clade Cycloneritimorpha

Theodoxus fluviatilis, common name the river nerite, is a species of small freshwater and brackish water snail with a gill and an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.

This widely distributed neritid snail species occurs from Europe to Central Asia. It has a thick shell with a calcified operculum. The coloration pattern on the shell is very variable. Theodoxus fluviatilis lives in freshwater and in brackish water, in rivers and lakes on stones. It feeds mainly by grazing on biofilms and diatoms.

Some of the populations of this species are spreading, and these can reach densities up to thousands of snails per square meter. Females lay egg capsules, each of which contains a large number of eggs, but only one snail hatches from the capsule. The snails reach sexual maturity in a year, and the total lifespan is 2 or 3 years.

Theodoxus fluviatilis was originally described under the name Nerita fluviatilis by Carl Linnaeus in 1758. Linnaeus' original text (the type description) in Latin was very short, and reads as follows:

Nerita fluviatilis, n. 632: testa rugosa, labiis edentilis. Habitat in Europa cataractis.

Which means in English: "Nerita fluviatilis, number 632: the shell is wrinkled, there are no teeth in the aperture. It inhabits rivers in Europe." Later, this species was moved to the genus Theodoxus Montfort, 1810. Theodoxus fluviatilis is in fact the type species of the genus Theodoxus. Anistratenko and colleagues designated the lectotype for Theodoxus fluviatilis in 1999 (an English translation was published by Anistratenko in 2005).

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