Rhyacophila gemona - Ross, 1938
Heavy Free-living Caddisfly
Taxonomic Status: Accepted
Related ITIS Name(s): Rhyacophila gemona Ross, 1938 (TSN 115172)
Unique Identifier: ELEMENT_GLOBAL.2.109674
Element Code: IITRI19560
Informal Taxonomy: Animals, Invertebrates - Insects - Caddisflies
 
Kingdom Phylum Class Order Family Genus
Animalia Mandibulata Insecta Trichoptera Rhyacophilidae Rhyacophila
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Concept Reference
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Concept Reference: Clemson University Department of Entomology (J.C. Morse, ed.). 2002. Last Updated 5 September 2006. Trichoptera World Checklist. Online. Available: http://entweb.clemson.edu/database/trichopt/index.htm.
Concept Reference Code: N02CLE01EHUS
Name Used in Concept Reference: Rhyacophila gemona
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 18Dec2017
Global Status Last Changed: 18Dec2017
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G3 - Vulnerable
Reasons: Although this species has a fairly limited range, threats are minimal and it is likely undersampled due to difficulty of identifying larval specimens.
Nation: United States
National Status: N2N3 (01Aug2005)
Nation: Canada
National Status: NU (24May2017)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Montana (S2), Washington (SNR)
Canada British Columbia (SU)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: Known from Washington and Montana (Crane Creek in Lake Co.) (Newell and Potter, 1975) and more recently from British Columbia (Wild Species report, 2015). Because of taxonomic issues with the identification of larval specimens, the extent of this species distribution may be much larger.

Area of Occupancy: 21-100 1-km2 grid cells
Area of Occupancy Comments: This represents a minimum as the extent of this species area of occupancy may be much larger due to taxonomic issues with the identification of larval specimens.

Number of Occurrences: 1 - 80
Number of Occurrences Comments: The number of occurrences is not precisely known because of taxonomic issues with the identification of larval specimens.

Population Size: Unknown

Number of Occurrences with Good Viability/Integrity: None to few (0-12)

Overall Threat Impact: Low
Overall Threat Impact Comments: Threats are minimal. However, this species prefers a narrow range of environmental conditions that are threatened by climate change.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Population, range, area occupied, and/or number or condition of occurrences have been unchanged or are remaining within a 10% fluctuation.

Long-term Trend: Relatively Stable (<=10% change)
Long-term Trend Comments: Population, range, area occupied, and/or number or condition of occurrences have been unchanged or are remaining within a 10% fluctuation.

Environmental Specificity: Narrow. Specialist or community with key requirements common.
Environmental Specificity Comments: This species prefers a narrow range of environmental conditions provided by steep-gradient, shaded, mossy cobbled, forested streams that are common of many habitats of our most narrowly restricted caddisflies.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Known from Washington and Montana (Crane Creek in Lake Co.) (Newell and Potter, 1975) and more recently from British Columbia (Wild Species report, 2015). Because of taxonomic issues with the identification of larval specimens, the extent of this species distribution may be much larger.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States MT, WA
Canada BC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
MT Lake (30047)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
17 Flathead Lake (17010208)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): SPRING/SPRING BROOK
Palustrine Habitat(s): FORESTED WETLAND
Habitat Comments: Found in forested mountain springs.
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Continue to monitor known populations for status of threats, site condition, and assess indices of abundance. Survey potential habitat for new populations. Seek long term protection for exceptional sites, particularly those without federal wilderness designation. Review forest management practices and other actions that may threaten populations by altering the hydrology and thermal characteristics of occupied streams, such as alteration of flow patterns, increased sunlight exposure, streambed substrate and water quality. Consider the feasibility of removal or mitigation of threats and how their this will impact the quality of habitat for the species, as well as other taxa of interest.
Population/Occurrence Delineation
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Group Name: Caddisflies

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical presence or current presence of single or multiple specimens (including larvae or adults) at a given location with potentially recurring existence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information. Sight records and photographs, though valuable, should not be accepted as the basis for new element occurrences as identification of caddisflies often requires close examination of the genitalia of adult males. Instead, such records should be utilized to further study an area to verify the element occurrence in that area.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Alternate Separation Procedure: None
Separation Justification: Wiggins and Mackay (1978) found caddisfly distributions separated by trophic category as related to stream resource availability in Eastern streams; and to a lesser degree in Western streams. Shredders predominated in upstream habitats in relation to grazers and collectors, but the proportion of shredders became smaller downstream. Groups have also been separated ecologically into lotic-erosional (running water riffles), lotic-depositional (running water pools and margins), lentic-limnetic (standing water), lentic-littoral (standing water, shallow shore areas), lentic-profundal (standing water, basin), and beach zone (Wallace and Anderson, 1996). For the purpose of occurrence separation, however, the same genera or species often occur across habitats making such habitat classifications impractical.

Regardless of habitat, caddisfly adults tend to remain somewhat near the emergence site (LaFontaine, 1981; Collier and Smith, 1998) where oviposition occurs. Dispersal away from emergence sites tends to be negatively correlated with density of vegetation along the dispersal corridor; caddisflies tend to disperse shorter distances in dense forest compared with more open vegetation (Collier and Smith, 1998). Although dispersal flights are common especially from temporary habitats, such flights are relatively short and only occur immediately following emergence (unlike some Coleoptera and Hemiptera that also disperse additionally in autumn to overwinter) (Cummins and Merritt, 1996). Kovats et al. (1996) estimated that 85% of all adult Hydropsychidae were collected within 100 m of the water's edge with most of the remainder collected within 250 m, although significant, though small, numbers were collected up to 1845 m inland (esp. for Hexagenia). It is worth noting that in some instances, large river caddisflies may disperse a distance greater than five km from the river, suggesting long distance dispersal (Huryn and Harris, 2000; Kovats et al., 1996). Kovats et al. (1996) suggested this longer distance dispersal is likely accidental. Separation distances (unsuitable and suitable) have therefore been set at five km.

Date: 18Oct2004
Author: Cordeiro, J.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 12Dec2017
NatureServe Conservation Status Factors Author: J. Cordeiro, rev D. Stagliano (2017)
Management Information Edition Date: 12Jan2018
Management Information Edition Author: Bachen, D.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Clemson University Department of Entomology (J.C. Morse, ed.). 2002. Last Updated 5 September 2006. Trichoptera World Checklist. Online. Available: http://entweb.clemson.edu/database/trichopt/index.htm.

  • Newell, R.L. and D.S. Potter. 1973. Distribution of some Montana caddisflies. Proceedings of the Montana Academy of Sciences 33: 12-21.

  • Ruiter, D.E., B.C. Kondratieff, R.A. Lechleitner, and R.E. Zuellig. 2005. An annotated list of the caddisflies (Trichoptera) of Mount Rainier National Park, Washington, USA. Transactions of the American Entomological Society 131(1/2): 159-187.

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