Mad River Mountainsnail (Oreohelix n. sp)

Photo not available for this species
Category: Molluscs
Ecosystems: Riparian areas
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The Mad River mountainsnail is a terrestrial gastropod. Their population is considered critically imperiled and declining. Many mountainsnail species and subspecies have specialized habitat requirements and very restricted ranges, low ability to disperse, and are vulnerable to disturbances such as logging, fire, unsustainable grazing, or introduced predators. 

Description and Range

Physical description

More information about the physical features of the Mad River mountainsnail is needed, although most species in their genus are 0.3 to 0.8 inches in length. Their shells are whitish in color and, typically, are slightly flattened with 4 to 6 whorls. 

Ecology and life history

The Mad River mountainsnail is a terrestrial gastropod of western North America. The species depends upon riparian habitat for its life requirements. They have been found in talus under black cottonwood (Populus balsamifera) or bigleaf maple (Acer macrophyllum), although insufficient surveys have been performed to determine the extent of their habitat use and needs. Most mountainsnails can be found in association with damp areas such as depressions in open grasslands and woodlands; they  are often associated with limestone outcrops, or areas with soil or rock with a fair percentage of lime.

Mountainsnails eat leaf litter, detritus, and microorganisms on the surface of logs, rocks, or soil.

The snails are hermaphroditic, having both male and female organs. They are "live-bearers"; the eggs hatch before leaving the uterus of the parent, and they raise their young within their shells until they reach a certain size.

It is not known how long they live, or how often they reproduce.

Geographic range

The Mad River mountainsnail has only been collected at one site on the Mad River in the Entiat Valley, eastern Chelan County. They have been found within the same range of the Chelan mountainsnail. Insufficient surveys have been conducted to determine their full range and little is known about their movements such as seasonal migrations. 


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.

The Mad River mountainsnail has not been ranked globally or within Washington state, but its population size is suspected to be declining and at a critically low level.

Conservation Threats and Actions Needed

  • Agriculture and aquaculture side effects
    • Threat: Fire, road building; need taxonomic clarification.
    • Action Needed: Delineate and protect occupied habitat.
  • Resource information collection needs
    • Threat: Taxonomic uncertainty may mean one or more taxa are in greater decline.
    • Action Needed: Taxonomic confirmation and description.

This species' climate vulnerability is assessed as "low to moderate." Climate vulnerability is a way to assess the degree to which a habitat or species is susceptible to, and unable to cope with adverse impacts of climate change.

Information is lacking for the Mad River mountainsnail, due to insufficient survey effort. Many mountainsnail species and subspecies have specialized habitat requirements and very restricted ranges, low ability to disperse, and are vulnerable to disturbance such as logging, fire, unsustainable grazing, or introduced predators. Human activities in open and grassy areas such as mountain-biking and off-road vehicles degrade mountainsnail habitat. Also detrimental are human-activities that create barriers or otherwise make snail movement more difficult, or that which alters the soil quality and texture or the temperature and humidity at the ground level.