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Lanx alta

(Tryon, 1865)

Highcap Lanx

G3Vulnerable Found in 7 roadless areas NatureServe Explorer →
G3VulnerableGlobal Rank
MediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.116471
Element CodeIMGASL7010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryInvertebrate Animal
Endemicendemic to a single nation
KingdomAnimalia
PhylumMollusca
ClassGastropoda
OrderBasommatophora
FamilyLymnaeidae
GenusLanx
Synonyms
Lanx klamathensisHannibal, 1912Lanx subrotunda(Tryon, 1865)
Other Common Names
highcap lanx (EN)
Concept Reference
Campbell, S. C., S. A. Clark, and C. Lydeard. 2017. Phylogenetic analysis of the Lancinae (Gastropoda, Lymnaeidae) with a description of the U.S. federally endangered Banbury Springs lanx. ZooKeys 663:107–132.
Taxonomic Comments
Genetic analysis of the lancine genera by Campbell et al. (2017) places Lanx klamathensis and L. subrotunda as junior synonyms of Lanx alta; this arrangement is accepted by MolluscaBase (2022).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2026-05-19
Change Date2026-05-19
Edition Date2026-05-19
Edition AuthorsEleanor Gaines (2019); rev. T. Cornelisse (2026)
Threat ImpactMedium
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Campbell et al. (2017) combined Lanx klamathensis and L. subrotunda into L. alta, resulting in a larger range and many additional records. However, species is vulnerable to multiple threats and has seen declines/extirpations in some areas.
Range Extent Comments
This species occurs from Douglas County, Oregon, south and east to Humboldt and Siskiyou Counties in California. The type locality is the Klamath River (Frest and Johannes 2005).
Occurrences Comments
There are approximately 30 occurrences between Oregon and California. Occurrences range from sparse to tens of thousands of individuals.
Threat Impact Comments
This species requires rocky substrates and high water quality. It is threatened by change in flow characteristics, reduced water quality, and transition from rocky to soft substrates (Frest and Johannes 1995, Johannes and Clark 2016, McMullen 2017). Primary threats include grazing, impoundments, and agricultural runoff.
Ecology & Habitat

Habitat

Found in spring-fed tributary streams, larger rivers, and major tributaries with stable cobble-boulder substrates and high water quality (Frest and Johannes 2005, Campbell et al. 2017).
Other Nations (1)
United StatesN3
ProvinceRankNative
CaliforniaS3Yes
OregonS2Yes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquaculture———
2.1 - Annual & perennial non-timber cropsRestricted (11-30%)Moderate or 11-30% pop. decline—
2.3 - Livestock farming & ranchingRestricted (11-30%)Moderate or 11-30% pop. decline—
2.3.2 - Small-holder grazing, ranching or farmingRestricted (11-30%)Moderate or 11-30% pop. decline—
7 - Natural system modificationsRestricted (11-30%)Serious or 31-70% pop. decline—
7.2 - Dams & water management/useRestricted (11-30%)Serious or 31-70% pop. decline—
9 - PollutionRestricted (11-30%)Moderate or 11-30% pop. decline—
9.3 - Agricultural & forestry effluentsRestricted (11-30%)Moderate or 11-30% pop. decline—
9.3.2 - Soil erosion, sedimentationRestricted (11-30%)Moderate or 11-30% pop. decline—
11 - Climate change & severe weatherLarge (31-70%)Moderate or 11-30% pop. decline—
11.2 - DroughtsLarge (31-70%)Moderate or 11-30% pop. decline—

—

Roadless Areas (7)
California (5)
AreaForestAcres
Monkey CreekSix Rivers National Forest9,017
North Fork SmithSix Rivers National Forest37,898
Orleans Mtn. CSix Rivers National Forest15,589
PacksaddleSix Rivers National Forest3,862
Pilot CreekSix Rivers National Forest9,192
Oregon (2)
AreaForestAcres
Cougar BluffUmpqua National Forest5,574
Limpy RockUmpqua National Forest6,782
References (12)
  1. Blevins, E. 2015. Lanx subrotunda Species Fact Sheet. Xerces Society for Invertebrate Conservation, prepared for US Forest Service. 13 pp.
  2. Blevins, E. 2015. L<i>anx klamathensis </i>Species Fact Sheet. Xerces Society for Invertebrate Conservation, prepared for US Forest Service. 11 pp.
  3. Campbell, S. C., S. A. Clark, and C. Lydeard. 2017. Phylogenetic analysis of the Lancinae (Gastropoda, Lymnaeidae) with a description of the U.S. federally endangered Banbury Springs <i>lanx</i>. ZooKeys 663:107–132.
  4. Freshwater Mollusk Conservation Society (FMCS). 2023. The 2023 checklist of freshwater gastropods of Canada, Mexico, and the United States. Considered and approved by the Gastropod Names Subcommittee December 2023. Online: https://molluskconservation.org/MServices_Names-Gastropods.html
  5. Frest, T.J. and E.J. Johannes. 1995a. Freshwater Mollusks of the Upper Klamath Drainage, Oregon. Final report to the Oregon Natural Heritage Program, 821 SE 14th, Portland, Oregon 97214. Contract #ORFO 092094. 68 pp. plus appendices.
  6. Frest, T.J. and E.J. Johannes. 1998. Freshwater Mollusks of the Upper Klamath Drainage, Oregon. 1998 yearly report to Oregon Natural Heritage Program and Klamath Project, USDI Bureau of Reclamation. Deixis Consultants, Seattle, Washington. 200 pp. + appendices.
  7. Frest, T.J. and E.J. Johannes. 2000b. A baseline mollusk survey of southwestern Oregon, with emphasis on the Rogue and Umpqua River drainages. Report for the Oregon Natural Heritage Program, Portland, Oregon. Deixis Consultants, Seattle, Washington. 403 pp.
  8. Johannes, E.J. and S.A. Clark. 2017. Freshwater mollusc declines, local extinctions and introductions noted in five northern California streams. The Dredgings. 57: 22-25.
  9. McMullen, L. 2017. Species Fact Sheet for Lanx alta. USDA Forest Service Region 6 and USDI Bureau of Land Management, Oregon and Washington Interagency Special Status and Sensitive Species Program. 19 pp. Available at: https://www.fs.fed.us/r6/sfpnw/issssp/documents5/sfs-ig-lanx-alta-2018-02.doc.
  10. MolluscaBase eds. 2022. MolluscaBase. Accessed at https://www.molluscabase.org.
  11. MolluscaBase eds. 2026. MolluscaBase. Accessed at https://www.molluscabase.org
  12. 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.