Socorro Springsnail

Pyrgulopsis neomexicana

Description

The Socorro springsnail is a minute aquatic snail with an elongated, light tan, spiral shell that measures only 0.1 in (0.25 cm) in length. Females are larger than males. The body and head are dark gray to black; the tentacles are dark at the base, lightening to pale gray at the tips. Snails of this family breathe through gills rather than lungs and have a lidlike structure on the foot called the operculum. Pyrgulopsis species are distinguished by characteristics of the structure of the male sexual organ. This snail has also been known as Amnicola neomexicana and Fontelicella neomexicana.

Behavior

The Socorro springsnail feeds on algae and elements of the organic film on the water. It lays eggs during the spring and summer.

Habitat

This snail species inhabits slowly flowing water near a thermal spring source. It is found on stones, among aquatic vegetation, and in the upper layer of organic muck on the bottom.

Distribution

The species was first described in 1916 from specimens taken from thermal springs west of Socorro (Socorro County), New Mexico. It no longer occurs in these springs.

The Socorro springsnail survives in a single spring in Socorro County. The main spring source has been impounded and only a single, small free-flowing source remains. The source pool measures less than a square meter in area; an outflow stream flows about 8 ft (2.5 m) to an irrigation ditch. The species inhabits the source pool and the outflow stream. The total population has been estimated at 5,000 individuals.

Threats

The greatest threat to the Socorro springsnail is its extremely limited distribution. Inhabiting a single small spring, the species is in danger of extinction through any change in its habitat. Pumping of the source pool, pollution, the introduction of predatory species, or vandalism, are threats to the species.

Conservation and Recovery

The spring is on private land and the owners did not object to the listing of the Socorro springsnail as Endangered.

Contact

U.S. Fish and Wildlife Service
Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103
http://southwest.fws.gov/

References

Hershler, R. and F. G. Thompson. 1987. "North American Hydrobiidae (Gastropoda: Rissoacea): Redescription and Systematic Relationships of Tryonia Stimpson, 1865 and Pyrgulopsis Call and Pilsbry. 1886." Nautilus 101(1):25-32.

New Mexico Department of Game and Fish. 1985.Handbook of Species Endangered in New Mexico. Santa Fe, New Mexico.

Taylor, D. W. 1987. Fresh Water Mollusks from New Mexico and Vicinity. Bulletin 116. New Mexico Bureau of Mines and Mineral Resources. Socorro, New Mexico.

Taylor, D. W. 1983. "Report to the State of New Mexico on a Status Investigation of Mollusca in New Mexico." New Mexico Department of Game and Fish, Santa Fe, New Mexico.