SPECIES FACT SHEET

Scientific Name: Colligyrus greggi (Pilsbry 1935)Common Name(s): Rocky Mountain duskysnailPhylum: MolluscaClass: GastropodaOrder: LittorinimorphaFamily: Amnicolidae (Hershler & Liu 2017)

Conservation Status:Global Status: G4 (10 November 2011)National Status (United States): N4 (03 June 2004)State Statuses: S2 (OR), S1 (WA)(NatureServe 2018)IUCN Red List: Least Concern (IUCN 2018)

Synonyms: Lyogyrus n. sp. 1, Colligyrus sp. 4, Amnicola greggii, Lyogyrus greggii, Colligyrus n. sp. 1

Taxonomic Notes:This species was originally described as Hydrobia greggi by Pilsbry (1935). Colligyrus greggi is the currently accepted name for this species (Hershler 1999; Liu et al. 2015; Hershler & Liu 2017); however, the Colligyrus type species (Hydrobia greggi Pilsbry, 1935) was previously treated as Lyogyrus, which it closely resembles, and Amnicola, which it appears more similar to morphologically (Burch & Tottenham 1980; Turgeon et al. 1998; Hershler 1999). Colligyrus greggi is generally placed in the Hydrobiidae family, though many conflicting studies have attempted to define the family and classify its morphologically similar spring and seep associated taxa (e.g., Taylor 1966; Ponder and Waren 1988; Bernasconi 1992). Kabat and Hershler (1993) showed that the Hydrobiidae family is polyphyletic, and subsequently, Wilke et al. (2001) elevated Amnicolinae (previously considered a subfamily of Hydrobiidae) to the family level based on molecular analyses.

Frest & Johannes (1993) originally identified populations of Colligyrus greggi in the Mount Hood-Columbia Gorge region as the Columbia duskysnail (Lyogyrus n. sp. 1), describing it as a Columbia Gorge endemic. At the time, this newly identified snail (in gray literature) was purportedly differentiated from the morphologically similar C. greggi

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(known as the Rocky Mountain duskysnail from the upper Snake River drainage) by the lighter body and penis pigmentation, and the smaller, less attenuated shell spire (Frest & Johannes 1995). Liu et al. (2015) compared six populations of the undescribed Columbia duskysnail from the Lower Deschutes River and Middle Columbia-Hood River basins to C. greggi specimens described from the Snake River drainage. A morphological and genetic analysis confirmed a close relationship between the Columbia duskysnail and C. greggi (Liu et al. 2015). Results from this study conclude that the undescribed Columbia duskysnail from the Lower Deschutes River and Middle Columbia-Hood River basins closely resembles C. greggi morphologically, and molecular analysis confirms it is conspecific with C. greggi, the Rocky Mountain duskysnail; thus these Columbia duskysnail populations, which occur in the Mt. Hood-Columbia Gorge area of Oregon and Washington, are now considered C. greggi.

Technical Description: Adult: Colligyrus is a genus of very small to minute, gilled, operculate aquatic spring snails in the family Amnicolidae, known as duskysnails. There are currently only three recognized species in the Colligyrus genus (Hershler 1999; Hershler et al. 2003; Hershler & Liu 2017). The Colligyrus genus is strongly differentiated from other amnicoline snails by a unique female genitalia groundplan (Hershler 1999). The genus is described as being a northwestern American amnicoline group having a small, globose to conical shell (up to 3.3 mm in length). Duskysnails in the Colligyrus genus are named for the dark mineral coating often characteristic of their shells (Frest & Johannes 2004).

Colligyrus greggi is described by Hershler (1999) and Frest & Johannes (1995; 1999) as follows:

Species Diagnosis: Within the genus, this species is diagnosed as having a small to medium-sized conical shell.

Species Description: Shell is clear to white, thin, and often transparent with a light brown or tan periostracum. It has a small to medium-sized shell that is conical and 1.7-3.3 mm in height. The shell has 3.75-4.5 whorls. C. greggi has a small, flat protoconch (about 1.5 whorls), broadly domed upper whorls, oval aperture, black mantle, and evenly light gray body and tentacles. The whorls are strongly

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convex, the suture deeply impressed, the spire ovately conic, and the umbilicus is small and open. Both penial lobes are unpigmented. Final whorls strongly rounded, with periphery even, midpoint at whorl center; suture deeply impressed.

Operculum light amber; outer margin without rim, dorsal surface weakly frilled. Attachment scar slightly thickened all around, especially along inner edge. Callus weakly developed.

Radula with about 155 rows of teeth; ribbon length, 1.5 mm, ribbon width, 94 µm; central tooth width, 25 (µm. Cutting edge of central tooth straight or very weakly indented; lateral cusps, 4-7; median cusp pointed, slightly broader and longer than laterals; basal cusps, 1-2; basal tongue narrowly triangular, even with or slightly shorter than lateral margins, basal sockets moderately excavated. Lateral tooth with slightly convex dorsal edge; lateral wing longer (150%) than cutting edge; tooth face taller than broad; central cusp weakly pointed, lateral cusps, 2-4 (inner), 3-4 (outer). Inner marginal teeth with 24—27 cusps;outer marginal teeth with 25-33 cusps.

For a further detailed description of the morphology of C. greggi, refer to Hershler (1999).

C. greggi is distinguished from similar C. depressus (the Harney Basin duskysnail; known only from its type locality in southeastern Oregon) in its narrower shell and presence of ctenidium (a comb-like gill, which is either absent or vestigial in C. depressus). Compared to C. greggi, C. depressus has a more distal position of the penial lobe, a longer bursal duct, discoidal shape of the anterior seminal receptacle, division of capsule gland into two distinct units, and a slit-like female genital aperture (Hershler 1999). See Appendix 4 for images of this species. Details of the genitalia of this species are illustrated in Hershler (1999).

Life History:The family Amnicolidae includes diverse, worldwide aquatic snails that are associated with cold water springs and seeps. Little is known regarding the feeding habits, growth, reproduction, or life span of this

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species, however life history information can be inferred from other better known closely related taxa. Amnicoline snails, in general, feed on algae, diatoms, and detritus. This species appears to be a perilithon and periphyton grazer (Frest & Johannes 1999). Most Colligyrus spp. have an annual life cycle (Frest & Johannes 2004). Similar to most species in the family, C. greggi has both male and female individuals (Hershler 1999). Females of this species are oviparous (producing eggs that hatch outside the body) (Hershler 1999). Oviparous females in this family are known to lay small eggs in single capsules on the leaves or stems of aquatic plants. With little body pigment and often thin, transparent shells, some species in the genus are thought to be photophobic and as a consequence cryptic in their habits (Frest & Johannes 2004).

Range, Distribution, and Abundance: Range: Colligyrus greggi was originally described from the upper Snake River drainage south of Jackson, Wyoming (Pilsbry 1935). Recent molecular analyses confirm Lower Deschutes River and Middle Columbia-Hood River basin populations of the Columbia duskysnail (Lyogyrus sp. n. 1, described by Frest & Johannes [1993; 1995] as a Columbia Basin endemic), to be a disjunct population of the Rocky Mountain duskysnail (C. greggi) (Liu et al. 2015). In addition to populations from the upper Snake River basin in Wyoming and Idaho, it is now known from the northeastern Great Basin of Idaho and Utah, and the Columbia-Hood River area in Oregon and Washington. The full extent of the range of C. greggi is uncertain pending taxonomic resolution of duskysnail populations in the West (Liu et al. 2015).

The resolved Mount Hood area records represent a significant range extension from that which was presented in Hershler (1999), but may not be unexpected, considering how little is known about the biology and distribution of this and other duskysnails in the West.

Distribution: Oregon populations of the Columbia duskysnail currently resolved to Colligyrus greggi are known from several locations in Clackamas, Hood River, and Wasco County in the Mount Hood National Forest, and Multnomah County on BLM land and in the Columbia River Gorge Scenic Area. In Washington, populations are known from private and state owned lands, and the Columbia River Gorge Scenic Area in Skamania County. In Clackamas County, C. greggi is documented in the Willamette River basin. Several records in Hood River County are from

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small springs or spring tributaries in the middle Columbia River basin. In Wasco County, this species was recorded from spring tributaries in the middle Columbia River basin and in the Deschutes River basin. In Multnomah County C. greggi is found from springs in the lower Columbia basin.

BLM/Forest Service Land:

Documented: In Oregon, this species is documented on the Mt. Hood National Forest, the Columbia River Gorge National Scenic Area, and BLM land in the Northwest Oregon District. In Washington it is documented in the Columbia River Gorge National Scenic Area.

Suspected: Given the proximity to known records, it is suspected in appropriate habitat on BLM lands in the Prineville District and Forest Service lands in the Gifford Pinchot National Forest.

Abundance: Abundance estimates of this species have not been conducted. Known collections range from 10 to 100 specimens (NMNH 2018).

Habitat Associations: Colligyrus spp. occur in cold water seeps, springs, streamlets, and sheltered large, rocky limnocrenes in the northwestern U.S. (Hershler 1999; Hershler et al. 2003; Frest & Johannes 2004). They are generally found in the coldest and most sheltered and shaded habitat of springs, including areas near spring sources (Frest & Johannes 2004). In Oregon, the habitat for this species includes Columbia Gorge tributaries and drainages originating from Mount Hood, where it is associated with small springs, spring outflows, and spring-fed streams (Frest & Johannes 1995; 1999). It is known from low to high elevations in cold, clean, well-oxygenated habitats (Frest & Johannes 1995; 1999). Frest & Johannes (1995) observed this species in shallow water with slow flows, commonly on soft mud substrates, but it has also been found on coarse substrates. In Oregon, C. greggi prefers pristine, low nutrient spring flows absent of macrophytes, but has been documented in larger springs with yellowcress (Rorippa) and water hemlock (Cicuta) (Frest & Johannes 1995). This species has been found associated with other Species of Concern, including Pristinicola hemphilli, a Forest Service Region 6

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Strategic Species (Frest & Johannes 1995; FS ISSSSP Database 2015; NMNH 2018).

A photograph (taken September 1993) of the habitat in the vicinity of the type locality in Wyoming is provided in Hershler (1999).

Threats: Freshwater gastropods presently have the highest extinction rate of any organism relative to their background extinction rate; this is likely a result of their limited dispersal abilities, endemism, and high vulnerability to habitat loss and degradation (Johnson et al. 2013). Mollusks with narrow ecological requirements like Colligyrus greggi in particular have a high risk of extinction. Consequently, taxa in the genus are sensitive to any modification of the cold-water spring environment that they inhabit, which could be a potential threat to their survival. Because this snail is associated with pristine springs and seeps, it is vulnerable to activities that disrupt its habitat. Thus, they may be particularly susceptible to threats from substantial quantities of pesticides, nitrates, or phosphates; habitat impacts causing unstable, soft substrate or substantial quantities of suspended fine sediment; hypoxic conditions; and areas subject to frequent water level fluctuations (Frest & Johannes 1993; 1995).

Specific threats to this species may include road construction, logging, and water diversions (USFWS 2011). Many springs in this species’ range in Oregon have been used for water supply or hatcheries, diverted or destroyed by road construction, or impacted by logging and/or severe fires (Frest & Johannes n.d.). Water diversions and groundwater pumping for campground, hatchery stock, and domestic water supplies can impact hydrologic flows in this species’ habitat. In addition, increased recreational activity may be a threat to this species at sites in the Columbia River Scenic Area and Mt. Hood National Forest. The locality near Timothy Lake on the Mt. Hood National Forest is a popular, high-use recreation area used by campers and boaters (including motorized)—with a day use area and campground nearby as well as the Pacific Crest Trail. Activities by hikers and campers may put additional pressures on aquatic habitats by trampling spring habitat and riparian vegetation, resulting in increased sedimentation. Impacts from a dam on the Oak Grove Fork Clackamas, which creates Timothy Lake reservoir,

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may also impact the hydrology of this locality, as flows are regulated to control water for hydroelectric plants.

Conservation Considerations: Research: There is a need to better understand the biology, distribution, status, and threats for this species in the West. The Columbia duskysnail, now known to be Colligyrus greggi, has received attention from the conservation community due to its purportedly narrow distribution, and threats to spring habitat in the Pacific Northwest (USFWS 2011). Under the Northwest Forest Plan, it was listed as a Re-cord of Decision (ROD) Survey and Manage species (USDA and USDI 1994). However, the USFWS (2012) in response to a petition to list the Columbia duskysnail, determined its addition to the federal list of threatened or endangered species was not justified in this case because it was not considered a “listable entity” (i.e., a distinct species).

Due to evidence of minor morphological differences between Columbia duskysnail populations in Idaho and Wyoming and those of C. greggi populations in the Mount Hood and Columbia River Gorge area, these Pacific Northwest populations may be considered a distinct conservation unit (Liu et al. 2015). Following the recent revision of the Mount Hood region specimens, there continues to be a need to examine the remaining understudied duskysnail populations in the Northwest to determine their taxonomic status (Liu et al. 2015).

Inventory: In Oregon and Washington, this species was known for many years as a Columbia Basin endemic (Frest & Johannes 1993; 1995). Recent findings that place the Columbia duskysnail with C. greggi in Idaho and Wyoming highlight the potential for additional undiscovered sites in the Columbia River basin of Washington and Oregon. Additionally, springs near known populations in the Mt. Hood National Forest and Columbia River Scenic Area could be identified and examined for this under-surveyed taxon.

Management: New and known sites and their associated watersheds could be managed to reduce the impacts of grazing, water diversions, recreation, and other practices that may adversely affect water quality. Habitat protection, including maintenance of water quality and substrate conditions, would likely benefit and help maintain this species.

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Version 1: Prepared by: Michele BlackburnThe Xerces Society for Invertebrate ConservationDate: December 2018

Reviewed by: Candace FallonThe Xerces Society for Invertebrate ConservationDate: December 2018

ATTACHMENTS:(1)References (2)List of pertinent or knowledgeable contacts (3)Map of known records in Oregon(4)Photographs and/or illustrations of this species(5)Survey protocol, including specifics for this species

ATTACHMENT 1: References: Bernasconi, R. 1992. Systematics of Hydrobiidae (Gastropoda Prosobranchia Monotocardia Rissoacea). A compendious survey with proposals for an improved classification. Disposed at the 11th International Malacological Congress, Siena. 14 pp.

Burch, J. B. & J. L. Tottenham. 1980. North American freshwater snails. Species list, ranges and illustrations. Walkerana 1(3):81-215.

Frest, T.J. and E.J. Johannes. [n.d.]. Northwestern U.S. sensitive nonmarine mollusks. Unpublished document. Available from E. Johannes. 287 pp.

Frest, T.J. and E.J. Johannes. 1993. Mollusc Species of Special Concern Within the Range of the Northern Spotted Owl. Final Report to Forest Ecosystem Management Working Group, USDA Forest Service.Deixis Consultants, Seattle, Washington. 98 pp.

Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices.

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Frest, T.J. and E.J. Johannes. 1999. Field guide to survey and manage freshwater mollusk species. Field guide: USFWS Regional Ecosystem Office and the USDI BLM Oregon State Office. Portland, OR. 128 pp.

Frest, T.J. and E.J. Johannes. 2004. Grazing effects on springsnails, Cascade-Siskiyou National Monument, Oregon. Prepared for World Wildlife Fund, Cascade-Siskiyou Ecoregion Office.

[FS ISSSSP Database] 2015. FINAL Region 6 Regional Forester Special Status Species List, July 13, 2015.

Hershler R. 1999. A systematic review of the hydrobiid snails (Gastropoda: Rissoidea) of the Great Basin, western United States. Part II. Genera Colligyrus, Fluminicola, Pristinicola, and Tryonia. The Veliger 42(4): 306-337.

Hershler, R., T.J. Frest, H-P. Liu, & E.J. Johannes. 2003. Rissooidean snails from the Pit River basin, California. The Veliger 46(4): 275-304.

Hershler, R. and H-P. Liu. 2017. Annotated checklist of freshwater truncatelloidean gastropods of the western United States, with an illustrated key to the genera. Technical Note 449. U.S. Department of the Interior, Bureau of Land Management, National Operations Center, Denver, CO. 152 pp.

IUCN 2018. The IUCN Red List of Threatened Species. Colligyrus greggi. Version 2018-1. Available at: http://www.iucnredlist.org [Accessed 9 November 2018].

Johnson, P.D., A.E. Bogan, K.M., Brown, N.M. Burkhead, J.R. Cordeiro, J.T. Garner, P.D. Hartfield, D.A.W. Lepitzki, G.L. Mackie, E. Pip, T.A. Tarpley, J.S. Tiemann, N.V. Whelan, and E.E. Strong. 2013. Conservation Status of Freshwater Gastropods of Canada and the United States. Fisheries. 38(6): 247-282.

Kabat, A. R. and R. Hershler. 1993. The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): review of classification and supraspecific taxa. Smithsonian Contributions to Zoology 547:1–94. Available at:

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https://repository.si.edu/bitstream/handle/10088/5560/SCtZ-0547-Lo_res.pdf?sequence=1. [Accessed 10 December 2018].

Liu, H.P., R. Hershler, and C.S. Rossel. 2015. Taxonomic status of the Columbia duskysnail (Truncatelloidea, Amnicolidae, Colligyrus). ZooKeys 514: 1-13.

NatureServe. 2018. “Colligyrus greggi.” NatureServe Explorer: An online encyclopedia of life [web application]. Feb. 2009. Version 7.1. NatureServe, Arlington, Virginia. Available at: http://www.natureserve.org/explorer/ (Accessed 9 November 2018).

[NMNH] National Museum of Natural History, Smithsonian Institution. 2018. Information provided with the permission of the National Museum of Natural History, Smithsonian Institution, 10th and Constitution Ave. N.W., Washington, DC 20560-0193. Available online at: https://www.nmnh.si.edu/ [Accessed 3 December 2018].

Pilsbry, H. A. 1935. Western and southwestern Amnicolidae and a new Humholdliana. The Nautilus 48:91-94. Available at: https://www.biodiversitylibrary.org/page/8520928#page/111/mode/thumb. [Accessed 9 November 2018].

Ponder, W. F. and A. Waren. 1988. Appendix: Classification of the Caenogastropoda and Heterostropha—a list of the family-group names and higher taxa: prosobranch phylogeny. Malacological Review, Supplement 4:288–326.

Taylor, D.W. 1966. A remarkable snail fauna from Coahuila, Mexico. The Veliger 9:152-228. Available at: https://www.biodiversitylibrary.org/page/42521795#page/186/mode/1up. [Accessed 10 December 2018].

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 ed. American Fisheries Society Special Publication 26, Bethesda, Maryland. 526 pp.

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[USDA USDI] United States Department of Agriculture, United States Department of the Interior. 1994. Standards and guidelines for management of habitat for late-successional and old-growth forest related species within the range of the northern spotted owl. Attachment A to the record of decision for amendments to Forest Service and Bureau of Land Management planning documents within the range of the northern spotted owl. 350 pp.

[USFWS] United States Fish and Wildlife Service. 2011. Endangered and threatened wildlife and plants; 90-day finding on a petition to list 29 mollusk species as threatened or endangered with critical habitat. Federal Register 76: 61826–61853.

[USFWS] United States Fish and Wildlife Service. 2012. Endangered and threatened wildlife and plants; 12-month finding on a petition to list 14 aquatic mollusks as endangered or threatened. Federal Register 77: 57922–57948.

Wilke, T., G. M. Davis, A. Falniowski, F. Grusn, M. Bodon and M. Szarowska. 2001. Molecular systematics of Hydrobiidae (Mollusca: Gastropoda: Rissooidea): testing monophyly and phylogenetic relationships. Proceedings of the Academy of Natural Sciences of Philadelphia 151:1-21.Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices.

Map references: [BLM GeoBOB Database] 2018. Bureau of Land Management Geographic Biotic Observations Database. GIS export provided to Candace Fallon, the Xerces Society, by Chelsea Waddell, Regional Wildlife, Botany & Fisheries Data Coordinator, September 2018.

[FS NRIS] 2018. Forest Service Natural Resource Information Service. GIS export provided to Candace Fallon, the Xerces Society, by Carol Hughes, Interagency Special Status/Sensitive Species Program, September 2018.

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Liu, H.P., R. Hershler, and C.S. Rossel. 2015. Taxonomic status of the Columbia duskysnail (Truncatelloidea, Amnicolidae, Colligyrus). ZooKeys 514: 1-13.

NMNH. 2018. Smithsonian National Museum of Natural History: Invertebrate Zoology Collection. [online database]. [Available at http://collections.nmnh.si.edu/search/iz/] [Accessed 3 December 2018].

[ORBIC] 2018. Oregon Biodiversity and Information Center. GIS export provided to Candace Fallon, the Xerces Society, by Lindsey Wise, Biodiversity Data Manager, November 2018.

ATTACHMENT 2: List of pertinent, knowledgeable contactsRobert Hershler. Research Zoologist, Emeritus, Smithsonian National Museum of Natural History, Washington DC.

Ed Johannes, Deixis Consultants, Seattle-Tacoma, Washington.

Hsiu-Ping Liu, Director Center for Advanced STEM Education, Metropolitan State University of Denver, Denver, Colorado.

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ATTACHMENT 3: Map of known Colligyrus greggi records from Oregon and Washington.

Known records of Colligyrus greggi in Oregon and Washington relative to Forest Service and BLM lands.

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ATTACHMENT 4: Photographs of this species

Scanning election micrographs of shells of Columbia duskysnail (A: USNM 1256484) and Colligyrus greggi (B: USNM 905375). Scale bar = 1.0 mm. Figure extracted from Liu et al. (2015); used with permission.

Photographs of ethanol preserved specimens of the Columbia duskysnail (USNM 1256484) showing pigmentation of body (A) and penis (B). Scale bars: 500 μm. Pl penial lobe, Pn penis. Figure extracted from Liu et al. (2015); used with permission.

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ATTACHMENT 5: Survey Protocol

Survey Protocol

Taxonomic group: Aquatic Gastropoda

Survey Protocol:

Please refer to the following documents for detailed mollusk survey methodology:

1. General collection and monitoring methods for aquatic mollusks:

See documents under the heading “Invertebrates – Mollusks” on the Interagency Sensitive and Special Status Species web page: https://www.fs.fed.us/r6/sfpnw/issssp/inventories/identification.shtml

2. Standard survey methodology that can be used by field personnel to determine presence/absence of aquatic mollusk species in a given waterbody, and to document species locations and habitats in a consistent format:

Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species: Preliminary Inventory and Presence/Absence Sampling. Version 3.1. Portland, OR. Interagency Special Status/Sensitive Species Program. U.S. Department of Interior, Bureau of Land Management, Oregon/Washington and U.S. Department of Agriculture, Forest Service, Region 6. 52 pp. Available at: https://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml

Inventory and Monitoring protocol page, with NRIS/GeoBOB field forms. Available at: http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml

ID services page, with current versions of field tags. Available at: http://www.fs.fed.us/r6/sfpnw/issssp/inventories/identification.shtml

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Species-specific Survey Details: Colligyrus greggi

This species has a disjunct distribution in the western US and appears to be rare in the Pacific Northwest based on recent molecular work to resolve populations on the Mount Hood National Forest (Liu et al. 2015). In Oregon, Colligyrus greggi is known only from several sites in the Mount Hood-Columbia River Gorge area in Hood River, Clackamas, Wasco, and Multnomah counties. In Washington, it is found at a few sites from the Columbia River Gorge in Skamania County. More work is necessary to determine the species' current status in Oregon and Washington, and surveys at both new and known sites (along with molecular analyses) will help reconcile duskysnail populations in this region. Standardized abundance estimates for this species at new and known sites will also assist future conservation efforts.

Surveys for this species can probably take place any time of year (records occur from January-December), although most records for C. greggi are from June through September. In Oregon and Washington, the habitat for this species includes Mount Hood and Columbia Gorge area tributaries and drainages, where it is associated with small springs, spring outflows, and spring-fed streams (Frest & Johannes 1995; 1999). It is known from low to high elevations in cold, clean, well-oxygenated habitats (Frest & Johannes 1995; 1999). Dip-netting and hand sieving are appropriate survey methods for Colligyrus species in spring habitat (Frest & Johannes 1995). Spring habitats with mud, sand, or silt substrate can be sampled by excavating small areas of bottom sediment to a depth of about 3 cm using a dip net with an 8 inch diameter and a 40 mesh size (Frest & Johannes 1995); C. greggi specimens collected recently for molecular analyses in the Mount Hood region were collected from spring habitat by hand using sieves (H-P. Liu pers. comm., 2018). Since duskysnails are difficult to identify based on morphology alone, it is possible that specimens from unstudied populations in the West may be assignable to Colligyrus, and that some are new species (Liu et al. 2015). Identification of this species is based on both morphology and molecular analyses, and other characters outlined in this fact sheet; expert identification of this species is recommended.

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References (Survey Protocol only):Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species: Preliminary Inventory and Presence/Absence Sampling. Version 3.1. Portland, OR. Interagency Special Status/Sensitive Species Program. U.S. Department of Interior, Bureau of Land Management, Oregon/Washington and U.S. Department of Agriculture, Forest Service, Region 6. 52 pp. [Available at: http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml].

Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices. Frest, T.J. and E.J. Johannes. 1999. Field guide to survey and manage freshwater mollusk species. Field guide: USFWS Regional Ecosystem Office and the USDI BLM Oregon State Office. Portland, OR. 128 pp.

Hershler, R. 2016. Personal communication with Kelli Van Norman. Research Zoologist and Curator of Mollusca, Smithsonian National Museum of Natural History, Washington, DC 20560-0163.

Liu, H-P. 2018. Personal communication with Michele Blackburn, the Xerces Society. Director, Center for Advanced STEM Education Department of Biology, Metropolitan State University of Denver, Denver, CO 80217. 3 December 2018.

Liu, H-P., R. Hershler, and C.S. Rossel. 2015. Taxonomic status of the Columbia duskysnail (Truncatelloidea, Amnicolidae, Colligyrus). ZooKeys 514: 1-13.

US Forest Service, Pacific Northwest Region. Invasive Aquatic Species. [Available at: http://www.fs.usda.gov/detail/r6/forest-grasslandhealth/invasivespecies/?cid=stelprdb5302184]

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