''Marstonia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ...

s 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, 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 ...

s in the family Hydrobiidae.

Distribution

Species in the genus ''Marstonia'' are distributed in springs, streams and lakes in eastern North America. Most of these species have extremely narrow geographic ranges and consequently have become a focus of conservation activities; two are federally listed as endangered and others are variously listed by state wildlife agencies.

Description

The freshwater gastropod genus ''Marstonia'' is composed of 15 small (shell height < 5.0 mm), ovate- to elongate-shelled species. ''Marstonia'' differs from the other eight North American nymphophiline genera in that the (female) oviduct and bursal duct join well in front of (instead of behind) the posterior wall of the

pallial cavity The mantle (also known by the Latin word pallium meaning mantle, robe or cloak, adjective pallial) is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of ...

. It has also been resolved as a well supported sub-clade within its subfamily based on mtDNA sequences.

Species

Eastern North American species of '' Pyrgulopsis'' are considered to be in separate genus ''Marstonia'' according to Thompson & Hershler (2002). * '' Marstonia agarhecta'' (F. G. Thompson, 1969) - synonym: ''Pyrgulopsis agarhecta'' F. G. Thompson, 1969 - Ocmulgee marstonia * '' Marstonia arga'' - F. G. Thompson, 1977 - synonym: '' Pyrgulopsis arga'' (F. G. Thompson, 1977) - ghost marstonia * '' Marstonia castor'' F. G. Thompson, 1977 - synonym: ''Pyrgulopsis castor'' (F. G. Thompson, 1977) - beaverpond marstonia * '' Marstonia halcyon'' F. G. Thompson, 1977 - synonym: '' Pyrgulopsis halcyon'' (F. G. Thompson, 1977) - halcyon marstonia * '' Marstonia hershleri'' (F. G. Thompson, 1995) - synonym: '' Pyrgulopsis hershleri'' F. G. Thompson, 1995 - Coosa pyrg * '' Marstonia letsoni'' (Walker, 1901) - synonym: '' Pyrgulopsis letsoni'' (Walker, 1901) - gravel pyrg * '' Marstonia lustrica'' (Pilsbry, 1890) - synonym: '' Pyrgulopsis lustrica'' (Pilsbry, 1890) - boreal marstonia * ''

Marstonia ogmorhaphe ''Marstonia ogmorhaphe'', common names the royal marstonia or royal springsnail, is a minute species of freshwater snail, an aquatic gastropod mollusk or micromollusk in the family Hydrobiidae, the mud snails. This species is endemic to Tennesse ...

'' (F. G. Thompson, 1977) - synonym: ''Pyrgulopsis ogmoraphe'' (F. G. Thompson, 1977) - royal springsnail * '' Marstonia olivacea'' (Pilsbry, 1895) - synonym: ''Pyrgulopsis olivacea'' (Pilsbry, 1895) - olive marstonia, it may be extinct * '' Marstonia ozarkensis'' (Hinkley, 1915) - synonym: ''Pyrgulopsis ozarkensis'' Hinkley, 1915 - Ozark pyrg, it may be extinct * '' Marstonia pachyta'' F. G. Thompson, 1977 - synonym: ''Pyrgulopsis pachyta'' (F. G. Thompson, 1977) - armored marstonia * '' Marstonia scalariformis'' (Wolf, 1869) - synonym: ''Pyrgulopsis scalariformis'' (Wolf, 1869) - moss pyrg Other species of ''Marstonia'' include: * '' Marstonia angulobasis'' F. G. Thompson, 2005 - Angled Marstonia * ''

Marstonia comalensis ''Marstonia comalensis'' is a species of minute freshwater snail with a gill and an operculum, an aquatic gastropod mollusk or micromollusk in the family Hydrobiidae. It is found in south central Texas, United States. ''Marstonia comalensis'' ...

'' (Pilsbry & Ferriss, 1906) - Comal Siltsnail * '' Marstonia gaddisorum'' F. G. Thompson, 2004 - Gaddis Marstonia Although ''Marstonia'' has been reviewed four times since 1978 (Thompson 1978, Hershler 1994, Thompson & Hershler 2002, Hershler & Liu 2011), three of its congeners have been little studied beyond their original descriptions and their anatomy is unknown. Two of these — '' Marstonia olivacea'', '' Marstonia ozarkensis'' — may be extinct and thus will likely remain incertae sedis.

References

This article incorporates CC-BY-3.0 text from the reference Hershler R. & Liu H.-P. (2011). "Redescription of ''Marstonia comalensis'' (Pilsbry & Ferriss, 1906), a poorly known and possibly threatened freshwater gastropod from the Edwards Plateau region (Texas)". ''

ZooKeys ''ZooKeys'' is a peer-reviewed open access scientific journal covering zoological taxonomy, phylogeny, and biogeography. It was established in 2008 and the editor-in-chief is Terry Erwin (Smithsonian Institution). It is published by Pensoft Publ ...

'' 77: 1-16. .

Distribution

Description

Species

References

Further reading