Alamosa Springsnail

Tryonia alamosae

Description

The Alamosa springsnail is a minute aquatic snail with a thin, translucent spiral shell up to 0.1 in (0.25 cm) in length. Females are about 50% larger than males. The body varies from black to gray and the tentacles are speckled with dark spots. This species breathes by means of gills rather than lungs.

Behavior

This snail feeds on algae and organic detritus. The eggs develop within the body of the female, and reproduction does not appear to be seasonal.

Habitat

This springsnail inhabits the slow-flowing currents of thermal springs. It is found on stones and submerged vegetation, but is absent from swift flowing water and muddy bottoms.

Distribution

The Alamosa springsnail was discovered in 1979, in Ojo Caliente (Socorro County), one of the largest thermal springs in New Mexico. It is currently known only from Ojo Caliente and a nearby system of smaller thermal springs. Although no population estimates have been made, the snail is considered abundant on gravel and vegetation in the shallow, slow-moving portions of the spring outflows.

Threats

The greatest threat to the Alamosa springsnail is its extremely limited distribution. Found in only a few thermal spring outflows, the species could face extinction through any change in its aquatic habitat. Impounding of the springs, pollution, the introduction of predatory species, or vandalism are ever-present threats to the species.

However, several of the smaller springs have been dug and impounded in the past. At present, the spring water flows through a canyon and then is diverted for irrigation use and to supply water to villages downstream. Future development of the springs to increase the water supply could threaten the Alamosa springsnail.

Conservation and Recovery

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

Contact

U.S. Fish and Wildlife Service
Regional Office, Division 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.

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.