Theodoxus Temporal range: | |
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An oblique left side view of a live Theodoxus fluviatilis | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Subclass: | Neritimorpha |
Order: | Cycloneritida |
Superfamily: | Neritoidea |
Family: | Neritidae |
Subfamily: | Neritinae |
Genus: | Theodoxus Montfort, 1810 [1] |
Type species | |
Theodoxus lutetianusMontfort, 1810 | |
Synonyms [2] | |
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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. [2]
The distribution of the genus Theodoxus includes Europe and northern Africa and also extends east to southern Iran. [3] No other species within Neritidae have sympatrical distribution with Theodoxus. [4] The distribution of the genus Theodoxus is an exception within Neritidae, because Neritidae live primarily in the southern hemisphere. [4] Species within Theodoxus are the only Neritidae snails, that live in temperate climate. [4]
Bunje & Lindberg (2007) presented the first phylogenetic hypothesis of the clade Theodoxus. [4] The evolution of the genus Theodoxus was affected by separating of Mediterranean Sea and Paratethys sea in Miocene. [4]
The shell in this genus is semiovular with a flat apertural plain. There is no umbilicus. The columella and inner whorls are dissolved. [3]
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. [5]
These animals live on stones, and often also under stones, in up to 5–6 m depth or deeper, feeding on algal covers. [3] Theodoxus needs rough surfaces in order to be able to digest its food, so a stony substrate is necessary. [3] Green algae [ clarification needed ] are not consumed; Theodoxus has no cellulases. [3] 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. [3]
There were no systematic review of the genus Theodoxus as of 2007. [4] 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. [6]
Species within the genus Theodoxus include:
Ancylus is a genus of very small, freshwater, air-breathing limpets. They are aquatic pulmonate gastropod mollusks in the tribe Ancylini within the family Planorbidae, the ram's horn snails and their allies.
Hydrobiidae, commonly known as mud snails, is a large cosmopolitan family of very small freshwater and brackish water snails with an operculum; they are in the order Littorinimorpha.
Neritidae, common name the nerites, is a taxonomic family of small to medium-sized saltwater and freshwater snails which have a gill and a distinctive operculum.
Theodoxus danubialis is a species of small freshwater snail with an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites. The species is considered as endangered in Germany, Austria and in the Czech Republic.
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.
Bithynia is a genus of small freshwater snails with an operculum, aquatic prosobranch gastropod mollusks in the family Bithyniidae.
Viviparus, common name the river snails, is a genus of large, freshwater snails with an operculum, aquatic gastropod mollusks.
Gyraulus is a genus of small, mostly air-breathing, freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails.
Radix is a genus of air-breathing freshwater snails, aquatic pulmonate gastropods in the family Lymnaeidae, the pond snails.
Hydrobia is a genus of very small brackish water snails with a gill and an operculum, aquatic gastropod mollusks in the family Hydrobiidae.
Melanopsis is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Melanopsidae.
Neritina, is a genus of small aquatic snails with an operculum in the family Neritidae, the nerites. They are as well marine, as brackish water, and sometimes freshwater gastropod mollusks
Pseudamnicola is a genus of small brackish water snails with an operculum, aquatic gastropod mollusks in the subfamily Pseudamnicolinae of the family Hydrobiidae.
Valvata is a genus of very small freshwater snails with an operculum, aquatic gastropod mollusks in the family Valvatidae, the valve snails.
Lithoglyphus is a genus of freshwater snails with gills and an operculum, a gastropod mollusk in the family Lithoglyphidae.
This article incorporates public domain text from the reference [3]