Corded purg

Corded purg
Drawing of lateral view of the shell of Pyrgulopsis nevadensis.
Conservation status
Extinct (IUCN 2.3)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Caenogastropoda clade Hypsogastropoda clade Littorinimorpha
Superfamily:	Rissooidea
Family:	Hydrobiidae
Subfamily:	Nymphophilinae
Genus:	Pyrgulopsis
Species:	P. nevadensis
Binomial name
Pyrgulopsis nevadensis (Stearns, 1883)[2]
Synonyms
Pyrgula nevadensis Sterns, 1883

The corded purg (Pyrgulopsis nevadensis) was a species of freshwater snails with a gill and an operculum, aquatic gastropod mollusk in the family Hydrobiidae.

Pyrgulopsis nevadensis is the type species of the genus Pyrgulopsis.^[3]

Shell description

The shell is small, somewhat elongated, variable, turreted and imperforate. The shell has 4½-5½ whorls, that are strongly unicarinate on periphery, otherwise smooth. The epidermis is shining, light straw in color or whitish. The suture is white. The suture is deeply and regularly impressed, made conspicuous by the approximating carina.^[3]

There existed also smooth variation. (plate II, figure 6-8.)

The aperture is very oblique, roundly ovate, with an angle on outer edge corresponding to the excavated carina, posteriorly sharply angled, well rounded before. The peritreme is continuous, almost rimate, closely appressed to parietal wall.^[3]

The operculum is light corneous, spiral and closely fitting the aperture.^[3]

Drawing of apertural view of the shell of Pyrgulopsis nevadensis.

Drawing of operculum of Pyrgulopsis nevadensis.

Drawing of apertural view of the shell of Pyrgulopsis nevadensis.

Anatomy

Jaw is thin and membranaceous.

Detailed description of radula was provided by Charles Emerson Beecher in 1886 (page 11-12).

Drawing of radula of Pyrgulopsis nevadensis.

Distribution

It was endemic to the United States. This species had a limited distribution, occurring only, so far as present information goes, in North-western Nevada, in Walker Lake and Pyramid Lake. Living forms have been collected only in the last-named locality.^[3]

References

This article incorporates public domain text from reference.^[3]

1. ^ Mollusc Specialist Group 2000. Pyrgulopsis nevadensis. 2006 IUCN Red List of Threatened Species. Downloaded on 7 August 2007.
2. ^ Stearns R. E. C. 1883. Proc. Phila. Acad. Nat. Sci.
3. ^ ^{a b c d e f} 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., page 9-14. Plate II., figures 1-10.

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