Oreohelix nevadensis
S.S. Berry, 1932
Schell Creek Mountainsnail
G1Critically ImperiledGlobal Rank
HighThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.117703
Element CodeIMGASB5270
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryInvertebrate Animal
Endemicendemic to a single state or province
KingdomAnimalia
PhylumMollusca
ClassGastropoda
OrderStylommatophora
FamilyOreohelicidae
GenusOreohelix
Concept ReferenceTurgeon, 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.
Conservation Status
Rank MethodLegacy Rank calculation - Biotics v1
Review Date2019-10-14
Change Date2002-10-08
Edition Date2019-10-14
Edition AuthorsMiskow, E. NNHP
Threat ImpactHigh
Range Extent<100 square km (less than about 40 square miles)
Number of Occurrences6 - 20
Rank ReasonsThis taxon is known from a few sites and has limited distribution, in high elevation areas predominantly consisting of limestone. It is found in areas with specific habitat elements, however these areas are remote. Wildfires during critical periods of snail activities above ground and through limestone talus, destruction of colony habitats by avalanche, long term drought, or long term climatic changes can have detrimental effects on colonies of land snails. Also, proposed mining exploration projects in the areas where they are known to occur could have severe impacts on existing populations.
Range Extent CommentsThis species is limited to small colonies and restricted to eastern White Pine County, Nevada.
Occurrences CommentsLimited to small colonies, 8 known populations are currently known and restricted to eastern White Pine County, Nevada.
Threat Impact CommentsMost Oreohelix spp. are endemic to single mountains or individual limestone outcrops within a mountain range. Ecological specialization makes them vulnerable to extirpation from fire, livestock grazing, road construction, mining activities and disturbance of rock talus causing loss of microhabitat quality affecting the ability for the species to survive fire events and climatic variations when aestivating.
Ecology & Habitat
Description
The Schell Creek mountainsnail (Oreohelix nevadensis) is the largest species of this genus in the Great Basin (mean diameter of 19.9 mm) and according to Pilsbry (1939) is most similar to the diverse Oreohelix haydeni (Gabb, 1869) group. Nomenclature of Oreohelix is still in flux, there may be disagreement at to proper relationships among species (Burke, 2013).
Diagnostic Characteristics
The shell of O. nevadensis is large for the Oreohelix genus as it occurs in Nevada, ranging from 12-18 mm in diameter, with a low-to-depressed spire, an angular-to-round body whorl, and a series of spiral “beaded welts” on both the base and apical body whorl surfaces (Pilsbry 1939). Pilsbry suggested that the shell anatomy of the Schell Creek Mountainsnail is similar in to O. haydeni hybrida which is found in the northern portion of the Wasatch Mountains in Utah.
Habitat
Habitat for O. nevadensis appear to be limestone rock slides in boulder talus with a matrix of soil and litter. O. nevadensis is associated with perennial springs or streams lined with narrow-leaf cottonwood (Populus angustifolia), willow (Salix sp.), red-osier dogwood (Cornus stolonifera), and wild rose (Rosa woodsii). At each locality O. nevadensis is sympatric with O. strigosa in the drainages and O. hemphilli on the drier, brush-covered, rocky slopes above the drainage.
Ecology
Snails have been found in an overstory of cottonwood, Pinyon Pine, and Rocky Mountain Juniper. Understory shrubs include chokecherry, dogwood, wild rose, and mountain spray.
Reproduction
Reproduction periods suggest that these animals reproduce in the early springs as adult animals had embryos in their genital track in mid-May (Ports, personal Communication 2019). This species as are all Oreohelix are hermaphrodites and give birth to live young, skipping the egg laying stage. This may be an adaptation to avoid freezing of eggs in the soil at higher elevations.
Terrestrial HabitatsBare rock/talus/scree
Palustrine HabitatsRiparian
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|
| Nevada | S1 | Yes |
Roadless Areas (1)
Nevada (1)
| Area | Forest | Acres |
|---|
| South Schell | Humboldt-Toiyabe National Forest | 125,614 |
References (1)
- 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.