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Meltwater Lednian Stonefly - Lednia tumana

Species of Concern
Native Species

Global Rank: G1G2
State Rank: S1
(see State Rank Reason below)

Agency Status

External Links

State Rank Reason (see State Rank above)
This stonefly is currently listed as an "S1" Species of Concern in MT due to extremely limited number of populations, range and/or habitat, making them highly vulnerable to extirpation in the state or even global extinction. They are only known from a few locations in Glacier National Park, mostly from larval collections. Currently at risk of becoming extinct due to the melting of the glaciers in Glacier National Park, which they depend on for their alpine glacier stream habitat. The stonefly was listed as Threatened under the Endangered Species Act in 2019.
General Description
The Meltwater Lednian Stonefly is a small, dark species of extremely cold glacier-fed streams at high elevations in Glacier Park south through the Mission and Swan Ranges of northwestern Montana. Little else is known about its habits or ecology, except that the adults emerge in mid-summer (July-August) and mate during this time.

Lednia tumana lives most of their lives (~1 years) in the water as nymphs (wingless, immature insects) and emerge as winged adults usually in July or August to find a mate and reproduce. Adult Lednia tumana are short lived (probably a week or less), making them difficult to collect at this life stage. They likely have poor dispersal as most stonefly adults are weak fliers.

Diagnostic Characteristics
Adults are 4.5-7.0 mm in length and dark brown with wings nearly as long or longer than the body (Baumann and Stewart 1980, Baumann and Kondratieff 2010). Adults fold their wings over their back and have antenna much longer than their head. Nymphs are a similar length (4.5-6.5 mm) but lack wings and live in streams. Lednia tumana nymphs lack gills and late instar nymphs are darkly colored. Lednia tumana can be separated from Zapada species by the lack of cervical gills.

Species Range
Montana Range Range Descriptions


Range Comments
Known only from the Northern Rocky Mountains in Banff National Park, Alberta, South through Glacier National Park into the Mission and Swan Mountains. It is present on both sides of the Continental Divide in Flathead and Glacier counties at 1610 m to at least 2332 m elevation (Baumann and Kondratieff 2010, and Muhlfeld et al. 2011). Populations in Glacier National Park appear to be experiencing local population fragmentation and range contractions, possibly linked to a warming climate (Muhlfeld et al. 2011, Jordan et al. 2016, and Muhlfeld et al. 2020).

Observations in Montana Natural Heritage Program Database
Number of Observations: 275

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

No migration is noted for this species, they are restricted in range and dispersal.

The larvae are found in first-order small alpine, mountain streams (Newell and Minshall 1976, and Muhlfeld et al. 2011), but only those closely linked to glacial run-off (Giersch 2002). A closely related species, Lednia tetonica, lives in streams with cold water temperatures (<8.5°C) that originate from glaciers. These stoneflies live in streams with meltwater from both surface glaciers and subterranean ice (e.g., rock glaciers). Streams tend to be stable (i.e., low variation in flow, not flashy) with cobble substrate in the alpine zone of mountains (i.e., usually above treeline). One study suggested they can persist in areas after glaciers have melted (Muhlfeld et al. 2020); however, rock glaciers are very common and cryptic features on the landscape that are the source of streams with very cold, and stable conditions (Brighenti et al. 2021).
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Stable isotope were used to investigate the diet of a closely related species in the Teton Range, Lednia tetonica. These stoneflies primarily ate biofilm (mixture of bacteria, fungi and algae growing on rocks) and the golden algae, Hydrurus (Jorgenson 2022). The proportion of food items consumed depended on their availability and the type of streams that the stonefly lived in (e.g., surface glacier or rock glacier). These stoneflies ate little coarse particulate organic matter (e.g., leaves; 9% on average) and some animal matter (e.g., predator).

The Lednian meltwater stonefly spends most of their life in the aquatic egg and nymph forms and may complete their life cycles in a single year or in 2 to 3 years. Adults are short-lived and emerge from the water to mate on vegetation along the stream by July or August. Ecologically this species is a cold-water stenotherm that is unable to tolerate warm water temperatures (mean temperture exceeding 10 degrees Celsius, maximum temperture exceeding 18 degrees Celsius) and is generally collected within a few hundred meters of the base of glaciers or snow melt derived streams (Muhlfeld et al. 2011).

Reproductive Characteristics
Adults are present and presumably mating takes place in July and August (Baumann et al. 1977, Giersch personal communication).

On October 4, 2016 the U.S. Fish and Wildlife Service proposed listing the Meltwater Lednian stonefly under the Endangered Species Act due to primarily to threats to the habitat and range of this species including climate change, loss of glaciers and permanent snowfields, and changes in stream flow and water temperature. On November 21, 2019 a notice was published in the Federal Register that the species' status was determined to be Threatened. Further information on status can be found on the U.S. Fish and Wildlife Service's Species Account

Threats or Limiting Factors
Lednia tumana lives in streams originating from subterranean ice (e.g., rock glaciers) and surface glaciers. Physiological studies of the stoneflies have shown that they can survive high temperatures (e.g., 25°C) for short time periods (Hotaling et al. 2020) and that their supercooling point is below 0°C (Hotaling et al. 2021). This stonefly was reared at five temperatures (1, 4, 7, 13 and 21°C) over a 31-day period. Results suggest that their ideal temperature lies between 1 and 13°C (Shah et al. 2023).

  • Literature Cited AboveLegend:   View Online Publication
    • Baumann, R. W. and K. W. Stewart. 1980. The nymph of Lednia tumana (Ricker) (Plecoptera:Nemouridae). Proceedings of the Entomological Society of Washington 82(4):655-659.
    • Baumann, R.W. and B.C. Kondratieff. 2010. The stonefly genus Lednia in North America (Plecoptera: Nemouridae). Illiesia. 6:315-327.
    • Brighenti, S., S. Hotaling, D.S. Finn, A.G. Fountain, M. Hayashi, D. Herbst, J.E. Saros, L.M. Tronstad, C.I. Millar. 2021. Rock glaciers and related cold rocky landforms: overlooked climate refugia for mountain biodiversity. Global Change Biol. 27:1504-1517. DOI: 10.1111/gcb.15510
    • Giersch, J. J. 2002. Revision and phylogenetic analysis of the verrula and alberta species group of Rhyacophila pictet 1834 with description of a new species (Trichoptera: Rhyacophilidae). Master's of Science Thesis. Montana State University, Bozeman, MT. 206 pp.
    • Green M.D., L.M. Tronstad, J.J. Giersch, A.A. Shah, C.E. Fallon, E. Blevins, T.R. Kai, C.C. Muhlfeld, D.S. Finn, and S. Hotaling. 2022. Stoneflies in the genus Lednia (Plecoptera: Nemouridae): sentinels of climate change impacts on mountain stream biodiversity. Biodiversity and Conservation. 31: 353-377.
    • Hotaling, S., A.A. Shah, K.L. McGowan, L.M. Tronstad, J.J. Giersch, D.S. Finn, H.A. Woods, M.E. Dillon, J.L. Kelley. 2020. Mountain stoneflies may tolerate warming streams: evidence from organismal physiology and gene expression. Global Change Biology, 26:5524-5538.
    • Hotaling, S., A.A. Shah, M.E. Dillon, J.J. Giersch, L.M. Tronstad, D.S. Finn, H.A. Woods, and J.L. Kelley. 2021. Cold tolerance of mountain stoneflies (Plecoptera: Nemouridae) from the high Rocky Mountains. Western North American Naturalist 81(1):54-62.
    • Jordan, S., J.J. Giersch, C.H. Muhlfeld, S. Hotaling, L. Fanning, T.H. Tappenbeck, and G. Luikart. 2016. Loss of genetic diversity and increased subdivision in an endemic alpine stonefly threatened by climate change. PLoS ONE 11(6): e0157386. doi:10.1371/journal.pone.0157386.
    • Jorgenson, K.L. 2022. Hydrologic source and trophic flexibility structure alpine stream food webs in the Teton Range, Wyoming. M.Sc. Thesis. Laramie, WY: University of Wyoming.
    • Muhlfeld, C.C., J.J. Giersch, F.R. Hauer, G.T. Pederson, G. Luikart, D.P. Peterson, C.C. Downs and D.B. Fagre. 2011. Climate change links fate of glaciers and an endemic alpine invertebrate. Climatic Change 106:337-345.
    • Muhlfeld, C.C., T.J. Cline, J.J. Giersch, E. Peitzsch, C. Florentine, D. Jacobsen, and S. Hotaling. 2020. Specialized meltwater biodiversity persists despite widespread deglaciation. Proceedings of the National Academy of Sciences May 2020, 202001697; DOI: 10.1073/pnas.2001697117
    • Newell, R.L and G.W. Minshall. 1976. An annotated list of the aquatic insects of Southeastern Idaho. Part I. Plecoptera. The Great Basin Naturalist 36(4): 501-504.
    • Shah, A.A., S. Hotaling, A.B. Lapsansky, R.L. Malison, J.H. Birrell, T. Keeley, J.J. Giersch, L.M. Tronstad, H.A. Woods. 2023. Warming undermines emergence success in a threatened alpine stonefly: a multi-trait perspective on vulnerability to climate change. Functional Ecology 37:1033-1043. DOI: 10.1111/1365-2435.14284
    • U.S. Fish and Wildlife Service. ECOS Environmental Conservation Online System. Last updated 2022. Meltwater lednian stonefly (Lednia tumana) species account. Accessed 15 November 2023.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Baumann, R.W, A.R. Gaufin, and R.F. Surdick. 1977. The stoneflies (Plecoptera) of the Rocky Mountains. American Entomological Society, Philadelphia.
    • Donald, D.B. and R.S. Anderson. 1977. Distribution of stoneflies (Plecotpera) of the Waterton River drainage, Alberta, Canada. Syesis 10:111-120
    • Giersch, J.J., S. Hotaling, R.P. Kovach, L.A. Jones, and C.C. Muhlfeld. 2016. Climate-induced glacier and snow loss imperils alpine stream insects. Global Change Biology. 13 p. plus Supporting Information. doi: 10.1111/gcb.13565
    • Hotaling, S., J.J. Giersch, D.S. Finn, L.M. Tronstad, S. Jordan, L.E. Serpa, R.G. Call, C.C. Muhlfeld, and D.W. Weisrock. 2019. Congruent population genetic structure but differing depths of divergence for three alpine stoneflies with similar ecology and geographic distributions. Freshwater Biology. 64:335-347
    • Kondratieff, B.C. and R.A. Lechleitner. 2002. Stoneflies (Plecoptera) of Mount Rainer National Park, Washington. Western North American Naturalist 62(4):385-404.
    • Merritt, R.W. and K.W. Cummins. 1996. An introduction to the aquatic insects of North America. 3rd Edition. Kendall/Hunt Publishing Company. Dubuque, Iowa. 862 pp.
    • Stewart, K.W. and D.D. Zeigler. 1984. The use of larval morphology and drumming in Plecoptera systematics, and further studies of drumming behavior. Annales De Limnologie 20(1-2):105-114.
    • Treanor, H.B., J.J. Giersch, K.M. Kappenman, C.C. Muhlfeld and M.A.H. Webb. 2013. Thermal tolerance of meltwater stonefly Lednia tumana nymphs from an alpine stream in Waterton-Glacier International Peace Park, Montana, USA. Freshwater Science 32(2): 597-605.
    • Tronstad, L.M., S. Hotaling, J.J. Giersch, O.J. Wilmot, and D.S. Finn. 2020. Headwaters fed by subterranean ice: potential climate refugia for mountain stream communities? Western North American Naturalist 80(3):395-407.
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Citation for data on this website:
Meltwater Lednian Stonefly — Lednia tumana.  Montana Field Guide.  .  Retrieved on , from