Gonidea angulata - (I. Lea, 1838)
Western Ridged Mussel
Other English Common Names: Rocky Mountain Ridged Mussel
Taxonomic Status: Accepted
Related ITIS Name(s): Gonidea angulata (I. Lea, 1838) (TSN 80033)
French Common Names: Gonidée des Rocheuses
Unique Identifier: ELEMENT_GLOBAL.2.109629
Element Code: IMBIV19010
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Gonidea
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Concept Reference
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Concept Reference: Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Gonidea angulata
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 06Nov2007
Global Status Last Changed: 01Dec1997
Rounded Global Status: G3 - Vulnerable
Reasons: This species is fairly widespread but is declining in terms of area occupied and number of sites and individuals; habitat continues to be threatened as some decline has occurred in area occupied and number of sites and individuals. Note this unusual species belongs to a monospecific genus with no living relatives, only fossil forms otherwise exist in the western U.S..
Nation: United States
National Status: N3 (26Oct2004)
Nation: Canada
National Status: N2 (01Aug2017)

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 California (S1S2), Idaho (S3), Montana (SH), Nevada (S1), Oregon (S2S3), Washington (S2S3)
Canada British Columbia (S2)

Other Statuses

Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: SC (14Jul2005)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Endangered (26Nov2010)
Comments on COSEWIC: This mussel, one of only a few species of freshwater mussel in British Columbia, is restricted in Canada to the Okanagan basin. Historically, channelization and water regulation in the Okanagan River have affected mussel beds and caused population reduction. Additional sites have been found since the original COSEWIC assessment (2003). Currently, Zebra and Quagga (dreissenid) Mussels are the most serious potential threat to the native mussel. Dreissenid mussels have had devastating effects on native unionid communities elsewhere, such as in the Great Lakes region. A recent assessment of the sensitivity of the Okanagan basin to dreissenid mussels demonstrated that the latter could spread quickly and establish intense infestation on native mussels once introduced. Within the foreseeable future, the introduction of dreissenids into the Okanagan basin is likely because they can survive for days out of water and are known to be transported between water bodies on trailered watercrafts; dreissenid mussels have been intercepted on trailered boats heading to British Columbia in recent years. Ongoing foreshore and riparian development, and some methods of control of invasive Eurasian Watermilfoil reduces habitat and affects water quality.
Designated Special Concern in November 2003. Status re-examined and designated Endangered in November 2010.

American Fisheries Society Status: Undetermined (01Jan1993)

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: This species formerly ranged from Central California, north to British Columbia and east to southern Idaho and northern Nevada (Burch, 1975; Taylor, 1981). In Oregon it historically occurred in rivers of the Coastal Range, and the main stem and tributaries of the Columbia River, including tributaries to the Snake and Malheur Rivers and John Day River mainstem (Brim Box et al., 2004). It remains in portions of the Snake River system, namely the Okanogan River in Washington, and Clearwater River, Hells Canyon and middle Snake River in Idaho, but is extirpated from many former locations (Frest and Johannes, 1995). Is "probably extinct in most of the Central Valley and southern California" (Taylor, 1981). It is absent from the Olympic Mountains, Washington and points north but occurs sporadically in Willapa Hills (sw Washington) and northwest Oregon, and occurs more continuously from southwest Oregon south to southern California (COSEWIC, 2003). In Canada, it is found in Columbia River system in southern British Columbia and known only from the main water bodies from Penticton south to the border (COSEWIC, 2003; Metcalfe-Smith and Cudmore-Vokey, 2004). Hovingh (2004) found it in abundance in the Humboldt River drainage in Nevada. Despite early reports by Henderson (1924; 1929; 1936) for Utah and Montana, more recent surveys (Chamberlin and Jones, 1929; Jones, 1940; Oliver and Bosworth, 1999; Gangloff and Gustafson, 2000; Lippincott and Davis, 2000) of these states have failed to find any individuals, however Gangloff and Gustafson (2000) speculate that if it were in Montana, it might be in free-flowing stretches of the Clark Fork River and perhaps some pristine headwater streams such as Rock Creek. Reports for Colorado were recently found to be misinterpreted California localities (Cordeiro, 2007).

Number of Occurrences: 21 - 300
Number of Occurrences Comments: It remains in portions of the Snake River system, namely the Okanogan River in Washington, and Clearwater River, Hells Canyon and middle Snake River in Idaho, but is extirpated from many former locations (Frest and Johannes, 1995). It also occurs in the Klamath River drainage in California and Oregon (Frest and Johannes, 1995) and Umpqua drainage in Oregon (Frest and Johannes, 2000). A recent survey of 115 sites in the Plumas, Tahoe, and Eldorado National Forests plus Lake Tahoe Basin management unit found it in only 1 site in Plumas NF (1 of 70+ streams) (Howard, 2008). Recently in California: Fall River, Pit River, Scott River, Klamath River, Napa River, and Shasta River (Howard, 2010). It is absent from the Olympic Mountains, Washington and points north but occurs sporadically in Willapa Hills (southwestern Washington) and northwest Oregon, and occurs more continuously from southwest Oregon south to southern California (COSEWIC, 2003). In Oregon, populations were recently confirmed in the Middle Fork John Day River and the lower main stem of the Umatilla River (Brim Box et al., 2003; 2006). Hovingh (2004) found it in abundance in the Humboldt River drainage (Lahonta basin) in northern Nevada (this population may have been overlooked in the past). Karen Mock (Utah State University, pers. comm., 2007) has collected specimens from the Chehalis River, Similkameen River, and Toppenish Creek in Washington; and Umatilla River, Middle Fork John Day River, and Owyhee River in Oregon. Lysne and Clark (2009) found it in the Bruneau River (survey area from Snake River confluence upstream to Hot Creek- 41 km) in Idaho. This species was not encountered in recent surveys of Montana (Gangloff and Gustafson, 2000) but there are historical records in the upper Columbia River watershed in western Montana (perhaps the Clark Fork River or Kootenai River) (Nedeau et al., 2005). In Canada, it is found in the Columbia River system in southern British Columbia and known only from the main water bodies (Kootenay, Columbia, and Okanagan Rivers) from Penticton south to the border but only the Okanagan recently (COSEWIC, 2003; Metcalfe-Smith and Cudmore-Vokey, 2004). British Columbia distribution includes the Columbia River system with recent specimens collected from Park Rill Creek (Okanagan River tributary), Shaha Lake, and Vaseux Lake (both Okanagan system); with earlier or historic collections from Osoyoos Lake, and Okanagan Lake (all Okanagan drainage) (COSEWIC, 2003) and Okanagan River and Falls (Scudder, 1996).

Population Size: 100,000 to >1,000,000 individuals
Population Size Comments: In general, U.S. populations of Gonidea angulata are regarded as declining. Documented densities in some areas are as high 183 per square meter and local populations can be in the tens of thousands (COSEWIC, 2003).

Number of Occurrences with Good Viability/Integrity: Unknown
Viability/Integrity Comments: The stronghold for this species is large tributaries of the Snake River and Columbia River in Washington, Idaho, and Oregon (Nedeau et al., 2005). In California, this species is sparsely dispersed and not found in dense beds except 3 sites on the mainstem Klamath River in Klamath National Forest and 1 site on the upper Pit River within the Modoc National Forest where thousands of individuals are densely packed near channel banks (Howard, 2010).

Overall Threat Impact: High
Overall Threat Impact Comments: In California much of former riverine habitat has been altered for irrigation, hydroelectric, and water supply projects (Taylor, 1981). The middle Snake River populations are threatened by agricultural runoff, fish farms, urbanization and dams (population in Little Granite Reservoir on the Snake thought to be extirpated by a water drawdown in 1993). Populations in the lower Columbia River system are threatened by impoundments, harbor and channel modifications and agricultural runoff (Frest and Johannes, 1995). In British Columbia and Idaho, threatened by loss or degredation of habitat (eutrophication, urbanization, impoundment, siltation) (COSEWIC, 2003).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: This species is "Declining in terms of area occupied and number of sites and individuals" (Frest and Johannes, 1995; COSEWIC, 2003). In California it has been extirpated throughout much of its original range, particularly in southern California and the Central Valley as well as many sites in the Snake and Columbia watersheds (Nedeau et al., 2005). It appears all mussels are extirpated from southern California, south of Santa Cruz (Howard, 2010). Hovingh (2004) found it to be stable or slightly increasing except in the Central Valley of southern California. A recent survey of 115 sites in the Plumas, Tahoe, and Eldorado National Forests plus Lake Tahoe Basin management unit found it in 15 sites (10 of 70+ streams); indicating significant decline in the region (Howard, 2008).

Long-term Trend: Decline of <50% to Relatively Stable
Long-term Trend Comments: This species formerly ranged from Central California, north to British Columbia and east to southern Idaho and northern Nevada (Burch, 1975; Taylor, 1981). It is "probably extinct in most of the Central Valley and southern California" (Taylor, 1981). Despite early reports by Henderson (1924; 1929; 1936) for Utah and Montana, more recent surveys (Chamberlin and Jones, 1929; Jones, 1940; Oliver and Bosworth, 1999; Gangloff and Gustafson, 2000; Lippincott and Davis, 2000) of these states have failed to find any individuals

Intrinsic Vulnerability: Moderately vulnerable
Intrinsic Vulnerability Comments: This species is the only known living taxon in the monospecific genus, with no living relatives likely anywhere in the world, although it has an extensive fossil record in the western U.S. (COSEWIC, 2003). As such, its loss if extinct would be a complete loss of the genus and all its uniqueness.

Environmental Specificity: Moderate to broad.
Environmental Specificity Comments: This species is more pollution tolerant than some other western unionids, however it is absent from highly polluted areas (Frest and Johannes, 1995). It is also more tolerant of habitat disturbance such as sedimentation (Vannote and Minshall, 1982).

Other NatureServe Conservation Status Information

Inventory Needs: Determine exact distribution in southern California and Canada.

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species formerly ranged from Central California, north to British Columbia and east to southern Idaho and northern Nevada (Burch, 1975; Taylor, 1981). In Oregon it historically occurred in rivers of the Coastal Range, and the main stem and tributaries of the Columbia River, including tributaries to the Snake and Malheur Rivers and John Day River mainstem (Brim Box et al., 2004). It remains in portions of the Snake River system, namely the Okanogan River in Washington, and Clearwater River, Hells Canyon and middle Snake River in Idaho, but is extirpated from many former locations (Frest and Johannes, 1995). Is "probably extinct in most of the Central Valley and southern California" (Taylor, 1981). It is absent from the Olympic Mountains, Washington and points north but occurs sporadically in Willapa Hills (sw Washington) and northwest Oregon, and occurs more continuously from southwest Oregon south to southern California (COSEWIC, 2003). In Canada, it is found in Columbia River system in southern British Columbia and known only from the main water bodies from Penticton south to the border (COSEWIC, 2003; Metcalfe-Smith and Cudmore-Vokey, 2004). Hovingh (2004) found it in abundance in the Humboldt River drainage in Nevada. Despite early reports by Henderson (1924; 1929; 1936) for Utah and Montana, more recent surveys (Chamberlin and Jones, 1929; Jones, 1940; Oliver and Bosworth, 1999; Gangloff and Gustafson, 2000; Lippincott and Davis, 2000) of these states have failed to find any individuals, however Gangloff and Gustafson (2000) speculate that if it were in Montana, it might be in free-flowing stretches of the Clark Fork River and perhaps some pristine headwater streams such as Rock Creek. Reports for Colorado were recently found to be misinterpreted California localities (Cordeiro, 2007).

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 CA, ID, MT, NV, OR, WA
Canada BC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Modoc (06049), Shasta (06089)
ID Adams (16003), Custer (16037), Elmore (16039), Gooding (16047), Idaho (16049), Jefferson (16051), Kootenai (16055), Lemhi (16059), Minidoka (16067), Owyhee (16073), Twin Falls (16083), Washington (16087)*
OR Benton (41003), Clackamas (41005), Columbia (41009), Coos (41011)*, Curry (41015), Deschutes (41017), Douglas (41019), Grant (41023), Harney (41025), Jefferson (41031), Klamath (41035), Linn (41043), Malheur (41045), Marion (41047), Morrow (41049), Multnomah (41051), Umatilla (41059), Wallowa (41063)*, Wasco (41065)*, Washington (41067), Wheeler (41069)*, Yamhill (41071)
WA Grays Harbor (53027)+, Lewis (53041)+, Okanogan (53047)+, Spokane (53063)+, Stevens (53065)+
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Upper Humboldt (16040101), North Fork Humboldt (16040102)*, Middle Humboldt (16040105)
17 Upper Kootenai (17010101)*, Middle Clark Fork (17010204)*, Lower Clark Fork (17010213)*, Upper Spokane (17010305)+, Hangman (17010306), Lower Spokane (17010307), Little Spokane (17010308), Colville (17020003), Chief Joseph (17020005), Okanogan (17020006), Similkameen (17020007), Methow (17020008), Upper Columbia-Entiat (17020010), Upper Yakima (17030001), Naches (17030002), Lower Yakima, Washington (17030003), Idaho Falls (17040201)+, Lake Walcott (17040209)+, Raft (17040210)*, Upper Snake-Rock (17040212)+, Salmon Falls (17040213)+*, Big Wood (17040219)+*, C. J. Idaho (17050101)+, Bruneau (17050102)+, Middle Snake-Succor (17050103)+, Upper Owyhee (17050104), South Fork Owyhee (17050105)*, Middle Owyhee (17050107)+, Crooked-Rattlesnake (17050109)+, Lower Owyhee (17050110)+, Middle Snake-Payette (17050115)+, Upper Malheur (17050116)+*, Weiser (17050124)+, Brownlee Reservoir (17050201)+*, Hells Canyon (17060101)+, Upper Grande Ronde (17060104), Lower Grande Ronde (17060106), Upper Salmon (17060201)+, Pahsimeroi (17060202)+, Middle Salmon-Panther (17060203)+, Lower Salmon (17060209)+, Little Salmon (17060210)+*, Lower Selway (17060302)+, South Fork Clearwater (17060305)+, Clearwater (17060306), Umatilla (17070103)+, North Fork John Day (17070202)+, Middle Fork John Day (17070203)+, Lower John Day (17070204)+*, Upper Deschutes (17070301)+*, Lower Crooked (17070305)+, Lower Columbia-Sandy (17080001)+, Lewis (17080002), Upper Willamette (17090003)+, Middle Willamette (17090007)+, Tualatin (17090010)+, Lower Willamette (17090012)+, Upper Chehalis (17100103), Lower Chehalis (17100104), Willapa Bay (17100106), North Umpqua (17100301)+, South Umpqua (17100302)+, Umpqua (17100303)+, Coquille (17100305)+*, Lower Rogue (17100310)+, Harney-Malheur Lakes (17120001)+*, Donner Und Blitzen (17120003)+
18 Mad-Redwood (18010102), Lower Eel (18010105), Williamson (18010201)+, Sprague (18010202)+, Upper Klamath Lake (18010203), Lost (18010204)+, Butte (18010205), Upper Klamath (18010206), Shasta (18010207), Scott (18010208), Lower Klamath (18010209), Salmon (18010210), Trinity (18010211), South Fork Trinity (18010212), Upper Pit (18020002)+, Lower Pit (18020003)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
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Basic Description: a freshwater mussel
Reproduction Comments: The glochidial host is not known.
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): BIG RIVER, CREEK, MEDIUM RIVER
Lacustrine Habitat(s): Deep water, Shallow water
Special Habitat Factors: Benthic
Habitat Comments: This species inhabits creeks and rivers of all sizes and can be found on substrates varying from firm mud to coarse particles; is rarely found in lakes or reserviors (Frest and Johannes, 1995; Taylor, 1981).
Economic Attributes Not yet assessed
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Management Summary
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Biological Research Needs: Determine fish host.
Population/Occurrence Delineation
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Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. 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.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
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: 06Sep2007
NatureServe Conservation Status Factors Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 26Jan2007
Element Ecology & Life History Author(s): Cordeiro, J.

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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  • Gonidea angulata/Rocky Mountain Ridged Mussel. 2006. Copyright Lea Gelling.

  • B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. Available: http://www.env.gov.bc.ca/wld/recoveryplans/rcvry1.htm

  • Brim Box, J., J. Howard, D. Wolf, C. O'Brien, D. Nez, and D. Close. 2006. Freshwater mussels (Bivalvia: Unionoida) of the Umatilla and Middle Fork John Day Rivers in eastern Oregon. Northwest Science, 80(2): 95-107.

  • Burch, J.B. 1975a. Freshwater unionacean clams (Mollusca: Pelecypoda) of North America. Malacological Publications: Hamburg, Michigan. 204 pp.

  • COSEWIC. 2003. Assessment and status report on the Rocky Mountain ridged mussel (Gonidea angulatat) in Canada. Committee on the status of endangered wildlife in Canada. Ottowa. 29+pp. (www.sararegistry.gc.ca/status/status_e.cfm)

  • COSEWIC. 2003c. COSEWIC assessment and status report on the Rocky mountain ridged mussel Gonidea angulata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa.
    vi + 29 pp.

  • COSEWIC. 2010c. COSEWIC assessment and status report on the Rocky Mountain Ridged Mussel Gonidea angulata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 56 pp.

  • Cannings, S.G., and R. Cannings. 1995. Rare Invertebrates of the South Okanagan. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 6pp.

  • Chamberlin, R.V. and D.T. Jones. 1929. A descriptive catalog of the Mollusca of Utah. Bulletin of the University of Utah, [Biological Series 1(1)] 19(4): 1-203.

  • Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, Ottawa. 446 pp.

  • Cordeiro, J. 2007. Confirmed absence of a relict population of Gonidea angulata (Lea, 1838) (Mollusca: Bivalvia: Unionidae) in Colorado. American Malacological Bulletin, 22: 165-167.

  • Fisheries and Oceans Canada. 2010c. Management Plan for the Rocky Mountain Ridged Mussel
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  • Fisheries and Oceans Canada. 2017g. Report on the Progress of Management Plan Implementation for the Rocky Mountain Ridged Mussel (Gonidea angulata) in Canada for the period 2011 ? 2016 Species at Risk Act Management Plan Report Series. Fisheries and Oceans Canada, Ottawa. iii + 18 pp.

  • French, L. 2005. Electronic database containing Gonidea angulata survey results from the Okanagan basin. Last updated April 2008.

  • Frest, T. J. and E. J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report to the Interior Columbia Basin Ecosystem Management Project. Walla Walla, WA, USA

  • Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report to Interior Columbia Basin Ecosystem Management Project. 273 pp + appendices.

  • Gangloff, M.M. and D.L. Gustafson. 2000. Freshwater mussels (Bivalvia: Unionoida) of Montana. Central Plains Archaeology, 8(1): 121-130.

  • Gustafson, R.G. and E.M. Iwamoto. 2005. A DNA-based indentification key to Pacific Northwest freshwater mussel glochidia: Importance to salmonid and mussel conservation. Northwest Science 79(4): 233-245.

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  • Henderson, J. 1936. The non-marine Mollusca of Oregon and Washington- supplement. University of Colorado Studies, 23(4): 251-280.

  • Henderson, J.B. 1929a. Non-marine mollusca of Oregon and Washington. University of Colorado Studies 17(2): 47-190.

  • Hovingh, P. 2004. Intermountain freshwater mollusks, USA (Margaritifera, Anodonta, Gonidea, Valvata, Ferrissia): geography, conservation, and fish management implications. Monographs of the Western North American Naturalist, 2: 109-135.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • Howard, J. 2010. Sensitive freshwater mussel surveys in the Pacific southwest region: Assessment of conservation status. Report prepared for USDA Forest Service, Vallejo, California. 57 pp.

  • Howard, J.K. 2008. Strategic inventory of freshwater mussels in the northern Sierra Nevada province. Repoort prepared by Western Mollusk Sciences (San Francisco, California) for USDA Forest Service, Vallejo, California. 45 pp. + app.

  • Ingram, W.M. 1948. The Larger Freshwater Clams of California, Oregon and Washington. Journal of Entomology and Zoology. 40:72-92.

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