Meltwater Lednian Stonefly - Lednia tumana
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This stonefly is currently listed as an "S1" Species of Concern in MT due to extremely limited and/or rapidly declining population numbers, range and/or habitat, making it highly vulnerable to extirpation in the state or even global extinction. Currently 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 it depends on for it's alpine snow-melt stream habitat. It was listed as a "candidate species" for listing under the Endangered Species Act in 2011.
The Meltwater Lednian Stonefly is a small, dark species of extremely cold glacier-fed streams at high elevations in Glacier Park. Little else is known about its habits or ecology, except that the adults have hatched by mid-summer (July-August) and are presumably mating during this time.
[From Baumann and Stewart 1980, Baumann and Kondratieff 2010] Male: Macropterous, wings hyaline with darker veins near cord; length of body 4.5-5.5 mm, dark brown, anterior abdominal segments lightly sclerotized. Female: body color and wings similar to male; length of body 5.5-7.0 mm. Male epiproct bilaterally symmetrical with dorsal groove extending from tip to near base, ventral sclerite flat and dark (bearling few stout ventral spines apically), apex narrowly pointed and extending beyond apex of dorsal sclerite, tip with dorsal groove terminating in arrowhead-like point; dorsal sclerite with borad bare base; hypoproct sclerotized, broad at base and narrowing towards apex; paraprocts with two lobes (dark inner one long and thin, light outer one short and broadly rounded with numerous hairs); tergum ten with median anterior groove bordered by pair of mace-like prongs which approach tip of epiproct. Female sternum seven broadly rounded, subgenital plate covering most of sternum eight, lateral margins bearing nearly rounded sclerotized lobes on either side of subgenital plate apex. Larva: gills absent, length of mature males 4.5-5.5 mm, mature females 5.5-6.5 mm. Dorsal surface of body with few small spines except at anterior margins of thoracic and anterior abdominal segments. Legs with numerous small spines, 3-5 larger spines present on dorsal margins of femora. Female larvae with large, truncate, plate-like lobe on dorsomedian margin of sternum eight. Cerci with whorls of spines on posterior margins of segments and sparse, small intercalary spinules on all segments.
Adults have hatched by mid-summer (July-August) and are presumably mating during this time.
Dorsal sclerite of male epiproct with two oblong patches of small spines that are of equal size, bare of hairs, lacking grooves.
Known only from the Northern Rocky Mountains in Banff National Park, Alberta, and in and around Waterton-Glacier International Peace Park; in Glacier National Park, Montana, 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; 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).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(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; Muhlfeld et al. 2011), but only those closely linked to glacial run-off (Giersch 2002).
Not described. Most species in the Nemouridae are shredders or collector-gatherers, utilizing coarse plant materials (Merritt and Cummins 1996), which could include mosses growing on the sides of the stream.
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).
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 primary 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. Further information on this proposed listing can be found on the U.S. Fish and Wildlife Service's Species Account
Threats or Limiting Factors
Specific threats to the populations of Lednia are largely related to global warming and the melting of glaciers and their associated snow melt streams. In general, stonefly populations are affected by changes to aquatic habitat such as alteration of flow patterns, streambed substrate, and thermal characteristics. Treanor et al. (2013) predicted chronic temperature maximas.
- 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, A.R. Gaufin, and R.F. Surdick. 1977. The stoneflies (Plecoptera) of the Rocky Mountains. American Entomological Society, Philadelphia.
- Baumann, R.W. and B.C. Kondratieff. 2010. The stonefly genus Lednia in North America (Plecoptera: Nemouridae). Illiesia. 6:315-327.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Additional ReferencesLegend: View Online Publication
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- Kondratieff, B.C. and R.A. Lechleitner. 2002. Stoneflies (Plecoptera) of Mount Rainer National Park, Washington. Western North American Naturalist 62(4):385-404.
- 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.
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