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Mountain-Prairie Region
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Meltwater lednian stonefly


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  • Meltwater lednian stonefly. Credit: Joe Giersch.

    Meltwater lednian stonefly. Credit: Joe Giersch.

Meltwater lednian stonefly (Lednia tumana)

The meltwater lednian stonefly (Lednia tumana) is a species of insect in the taxonomic order Plecoptera, also known as the stonefly order.  Immature meltwater lednian stoneflies (nymphs) are aquatic and emerge from streams at specific times to complete their development into adults.  Meltwater lednian stonefly adults are generally brown in color, possess two sets of translucent wings and are very small; ranging from 0.16 to 0.24 inches in body length. 

Meltwater lednian stoneflies are known to occur in 113 streams; 109 in Glacier National Park, Montana, 2 in the Bob Marshall and Great Bear Wilderness, Montana, 1 on the Flathead Indian Reservation, Montana, and 1 in Waterton Lakes National Park in Alberta, Canada.  All occupied streams are high-elevation, alpine streams originating from cold water sources, including glaciers and small icefields, permanent and seasonal snowpack, alpine springs, and glacial lake outlets.  Meltwater lednian stonefly are known from streams where mean and maximum water temperatures do not exceed 50°F and 64°F, respectively, although the species can withstand higher water temperatures (~68°F) for short periods of time.

Meltwater lednian stoneflies occupy the most upstream reaches of alpine streams, typically occurring within the first one half mile of stream, starting at the meltwater source.  Therefore, they are sensitive to temperature changes and are considered to be a barometer for the effects of climate change in the alpine environment. 

Recent actions & links »

November 21, 2019: The U.S. Fish and Wildlife Service will protect the meltwater lednian stonefly and western glacier stonefly as threatened under the Endangered Species Act in a final listing decision announced today.

October 31, 2017: The U.S. Fish and Wildlife Service has reopened the comment period for an October 4, 2016, proposed rule to list the western glacier stonefly and the meltwater lednian stonefly as threatened species under the Endangered Species Act.  The comment period is being reopened to accept additional comments on new information about the range of the species.

October 3, 2016: The U.S. Fish and Wildlife Service is proposing a rule to list the meltwater lednian stonefly and western glacier stonefly as threatened under the Endangered Species Act. A threatened listing means the stoneflies are likely to become in danger of extinction in the foreseeable future.  The public is invited to comment on this proposal until December 5, 2016.

August 18, 2009:  After an initial review of a petition submitted by the WildEarth Guardians, the Service determined that the Bearmouth mountainsnail, Byrne Resort mountainsnail, and meltwater lednian stonefly may be warranted for listing under the Endangered Species Act.  With that determination, the Service commenced status reviews for the three species.

April 5, 2011:  The Service completed a 12-month status review of the meltwater lednian stonefly and determined that the meltwater lednian stonefly is warranted for listing, but is precluded by higher priority actions.  The species listing priority number (LPN) is 4, meaning the identified threats to the species are high in magnitude but the immediacy of the threats is non-imminent.

In the same 12-month finding, we also found that the Bearmouth and Byrne Resort mountainsnails do not warrant protection under the Act.  The Bearmouth mountainsnail and Byrne Resort mountainsnail are terrestrial mollusks commonly called “mountainsnails.”  Because these mountainsnails are not recognized as species by the scientific community, they are not listable entities as defined by the ESA.  Since we have concluded that the two petitioned mountainsnails are not listable entities, an analysis of threats is not required under the ESA.  Therefore, we will take no further action with these species at this time.

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The mission of the U.S. Fish and Wildlife Service is working with Others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American People.
Last modified: January 06, 2021
All Images Credit to and Courtesy of the U.S. Fish and Wildlife Service Unless Specified Otherwise.
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