''Pyrgula annulata'' 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 freshwater snail with a

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

and an operculum, an aquatic gastropod

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

Hydrobiidae 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. Distribution Hydrobiidae are found in much of the world, ...

. ''Pyrgula annulata'' is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

of the genus ''Pyrgula''.

Distribution

This species occurs in Switzerland, Italy, Croatia, and Albania.

References

External links

AnimalBase info
* black and white drawings of shell: ** Adams H. & Adams A. 1858. ''The genera of recent Mollusca: arranged according to their organization''
plate 32
figure 7. ** Call R. E. & Pilsbry H. A. 1886. ''On Pyrgulopsis, a new genus of rissoid mollusk, with description of two new forms''
Proceeding Davenport Academy of Natural Sciences, volume V.
pag
9
14
Plate II.
figures 11-12. Hydrobiidae Gastropods described in 1758 Taxa named by Carl Linnaeus {{Hydrobiidae-stub