''Bythinella reyniesii'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of very small

freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...

, an aquatic

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family

Amnicolidae Amnicolidae is a family of small freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the superfamily Rissooidea. This family is in the clade Littorinimorpha (according to the taxonomy of the Gastropoda by Bouchet & R ...

Distribution

These snails live in

spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a ...

s. They were long believed to occur only in

Andorra , image_flag = Flag of Andorra.svg , image_coat = Coat of arms of Andorra.svg , symbol_type = Coat of arms , national_motto = la, Virtus Unita Fortior, label=none (Latin)"United virtue is stro ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

, and parts of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. This disjunct distribution was puzzling, until it was realized that the populations assigned to several other supposedly distinct species actually seem to all belong to one species. In fact, ''Bythinella reyniesii'' is probably widespread from western

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

and nearby

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

through central and eastern France to Andorra.Bichain J.-M.. Gaubert P., Samadi S. & Boisselier-Dubayle M.-C. (2007). "A gleam in the dark: Phylogenetic species delimitation in the confusing spring-snail genus ''Bythinella'' Moquin-Tandon, 1856 (Gastropoda: Rissooidea: Amnicolidae)". '' Molecular Phylogenetics and Evolution'' 45(3): 927–941.
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Description and genetics

These are small snails, with a nearly

cylindrical A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...

shell measuring just over 2 mm in length. There is little morphological and almost no genetic variation between the supposed "species". Thus, even though the proposed synonymy resulted from mtDNA COI and nDNA

ITS1 Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. I ...

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...

data analyses applied to the

phylogenetic species concept In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sex ...

(which does not recognize

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

), as opposed to the morphologically diverse ''

Bythinella bicarinata ''Bythinella bicarinata'' is a species of very small freshwater snail, an aquatic gastropod mollusk in the family Amnicolidae. Shell description The shell of this species measures about 2.2–2.6 mm long and has a pupoidal shape (shaped ...

'' it might not even be warranted to accept the formerly distinct taxa as subspecies.

Conservation status

The northeastern specimens formerly separated in ''Bythinella compressa'' were classified as Vulnerable (B1+2c), as they were known from less than ten freshwater springs which are affected by pollution. ''Bythinella reyniesii'', in the traditional sense was classified as a Species of Least Concern (meaning it is not considered globally threatened), and this assessment applies to the species in the expanded sense also.

References

{{DEFAULTSORT:Bythinella Reyniesii Bythinella Gastropods described in 1851 Taxonomy articles created by Polbot