''Borysthenia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of small

freshwater snail Freshwater snails are gastropod mollusks that 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 t ...

s with an operculum, aquatic

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the family

Valvatidae ''Valvatidae'', the valve snails, is a taxonomic family of very small freshwater snails with an operculum, aquatic gastropod mollusks. Taxonomy The family Valvatidae has no subfamilies (according to the taxonomy of the Gastropoda by Bouche ...

, the valve snails. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

of ''Borysthenia'' is not circular."Genus summary for ''Borysthenia''"

AnimalBase AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and p ...

, last modified 28 February 2009, accessed 22 May 2011. Animals are

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...

Species

The genus ''Borysthenia'' contains the following species: * † '' Borysthenia goldfussiana'' (Wüst, 1901) * † '' Borysthenia intermedia'' Kondrashov, 2007 - from the Middle Pleistocene of Oka- Don PlainKondrashov P. E. (2007). "New gastropod species from the Pleistocene of the Upper Don basin". ''

Paleontological Journal ''Paleontological Journal'' () is a monthly peer-reviewed Russian journal of paleontology Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the ...

'' 41(5): 513-519. . * '' Borysthenia menkeana'' (Jelski, 1863) * ''

Borysthenia naticina ''Borysthenia naticina'' is a species of small freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Valvatidae, the valve snails. Distribution This species occurs in the Pontic and Baltic regions as follow ...

'' (Menke, 1845) - type species as ''Valvata jelskii'' Crosse, 1863

References

{{Taxonbar, from=Q4946885 Valvatidae Taxa named by Wassili Adolfovitch Lindholm Gastropod genera Extant Middle Pleistocene first appearances