Pomatiopsis lapidaria - (Say, 1817)
Slender Walker
Taxonomic Status: Accepted
Related ITIS Name(s): Pomatiopsis lapidaria (Say, 1817) (TSN 70737)
French Common Names: pomatiopsis lapidaire
Unique Identifier: ELEMENT_GLOBAL.2.107975
Element Code: IMGASJ9060
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Snails
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Gastropoda Neotaenioglossa Pomatiopsidae Pomatiopsis
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Concept Reference
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: Pomatiopsis lapidaria
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 05Mar2015
Global Status Last Changed: 14Sep1999
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G5 - Secure
Reasons: This species is ranked as secure in view of its wide distribution, presumed large population, and lack of known threats.
Nation: United States
National Status: N5 (14Sep1999)
Nation: Canada
National Status: N3 (07May2013)

U.S. & Canada State/Province Status
United States Alabama (S4), Connecticut (S1), Delaware (S1), Illinois (SNR), Indiana (SNR), Iowa (SNR), Kansas (S1), Kentucky (S4), Louisiana (SNR), Maryland (SNR), Massachusetts (S1), Michigan (SNR), Missouri (S3), New Jersey (SNR), New Mexico (SNR), New York (S3), North Carolina (SU), Ohio (S2), Oklahoma (S4?), Pennsylvania (S1S3), South Carolina (SNR), South Dakota (SNR), Tennessee (S5?), Texas (SNR), Virginia (S4), West Virginia (S3), Wisconsin (SH)
Canada Ontario (S3), Quebec (SNR)

Other Statuses

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Candidate (Low) (26Jan2015)

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 ranges from the Great Lakes and St. Lawrence drainages in Canada and the eastern United States, from Massachusetts and Connecticut south to Georgia and west to Iowa, Missouri, Kansas, Texas and New Mexico (Burch 1989, Clarke 1981, Wu et al. 1997, Stewart 2006).

Number of Occurrences: > 300
Number of Occurrences Comments: This species is represented by a large number of occurrences (subpopulations). It is uncommon in the western part of the range. Isolated populations have been found in Oklahoma, Texas, and New Mexico with spotty occurrences (Burch, 1989). In Kansas, this species has limited distribution and lack of habitat; it is known from a marsh in southwestern Atchison County (Angelo et al. 2002). Stephen (2015) contains a single record of this species in Nebraska without specific locality data.

Population Size: >1,000,000 individuals
Population Size Comments: Population is presumed large. In Kansas, Franzen (1944) reported P. lapidaria as being found in considerable numbers in the Muscotah Marsh (the only known location). Liechti (1984) determined a mean density of 1,255 individuals per square meter in raised portions of the marsh (Layher 2003).

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact Comments: No known threats.

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other NatureServe Conservation Status Information

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species ranges from the Great Lakes and St. Lawrence drainages in Canada and the eastern United States, from Massachusetts and Connecticut south to Georgia and west to Iowa, Missouri, Kansas, Texas and New Mexico (Burch 1989, Clarke 1981, Wu et al. 1997, Stewart 2006).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, CT, DE, IA, IL, IN, KS, KY, LA, MA, MD, MI, MO, NC, NJ, NM, NY, OH, OK, PA, SC, SD, TN, TX, VA, WI, WV
Canada ON, QC

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
CT Middlesex (09007)
KS Atchison (20005)
MA Berkshire (25003)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Lower Connecticut (01080205)+, Housatonic (01100005)+
10 Delaware (10270103)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: A small amphibious snail.
General Description:
From Layher (2003):
Pratt (1935) describes the slender walker snail as follows: shell slender, dark brown in color, and shining, with six whorls, 6.5 mm long and 3 mm wide. Franzen (1944) describes the slender walker snail as amber to dark brown, glossy, perforate, operculate, subconic shell consists ofstrongly inflated whorls regularly increasing in size toward the body whorl and separated by a sharply and deeply incised suture. The outer lip of the oval aperture is simple while the inner is somewhat reflected and continuous over the body whorl. The surface is marked with fine, microscopic vertical striations and is somewhat granular.

Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Palustrine Habitat(s): Bog/fen, HERBACEOUS WETLAND, TEMPORARY POOL
Habitat Comments: This species is amphibious and is found living either on moist ground or low on stems and leaves of sedges, reeds, and cattails and, although Baker (1928) lists the snail as amphibious, it is never found submerged except by ephemeral events as snails can remain submerged for several days but prefer terrestrial conditions with relative humidity conditions nearing saturation (Layher, 2003). P. lapidaria appears not to be limited by stream size, since it has been reported from bodies of water varying from temporary streams, which may be dry part of the year, to rivers as large as, or larger than, the Grand River in Michigan (Dundee, 1957). Pomatiopsis cincinnatiensis has more uniform and somewhat linear distribution along streams than Pomatiopsis lapidaria which, although has a wider overall range, always has very "spotty" distribution, particularly in Typha swamps, grassy hummocks in low pastures, etc. (van der Schalie and Dundee, 1955). In the Hiwassee basin in Tennessee, Coney et al. (1982) found it had a broad habitat breadth associated with only low elevation and with an affinity for the Oak-Cedar sere, particularly oak-hickory-sugar maple forests, and was found in the leaf litter and log microhabitats.
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Freshwater Snails

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 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: Unlike most freshwater mussels [possibly excepting Uniomerus tetralasmus (Say, 1831) (see Isley, 1914)], some freshwater pulmonates are able to survive in intermittent streams and ponds by settling into sediment on the bottom and aestivating in otherwise dry or frozen conditions. Some species (e.g. Stagnicola spp.) may form a sheet of mucus just within the aperture called an epiphragm that effectively seals the snail from harsh external conditions (Jokinen, 1978; Brown, 1991). For ephemeral or intermittent water species, it may be particularly difficult to define the limits of an occurrence. Movement out of the water for the purposes of aestivation is on the order of cm (Jokinen, 1978), not m or km, so this behavior should not affect separation distance between occurrences. Species that may be found in intermittent waters include: Aplexa elongata, Fossaria bulimoides, F. dalli, F. modicella, F. obrussa, F. parva, Gyraulus circumstriatus, G. crista, G. parvus, Laevapex fuscus, Physa vernalis, Physella gyrina, Planorbella campestris, Planorbula armigera, Stagnicola caperata, S. elodes, S. exilis.
Separation Barriers: Separation barriers are largely based on permanent hydrological discontinuity between water bodies, with distances of 30 meters or greater between maximum high water marks constituting a separation barrier. Additional barriers are chemical and/or physical and include any connecting water body (regardless of size) with one or more of the following on a permanent basis: no dissolved calcium content, acidity greater than pH 5, lack of dissolved oxygen, extremely high salinity such as that found in saline lakes and brine waters, or temperature greater than 45

An additional physical barrier, particularly for flowing water, is presence of upland habitat between water connections. High waterfalls and anthropogenic barriers to water flow such as dams are barriers as they limit movement in an upstream direction.

Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 2 km
Alternate Separation Procedure: Freshwater cave species (mostly prosobranchs) may occur near entrances to very deep in cave systems with specimens occurring on the undersides of small stones in riffle areas (Hershler et al., 1990). For cave species, separation distance cannot often be determined accurately due to varying degrees of accessibility to occupied cave habitat. In these instances, each cave where an observation or collection was recorded (see Minimum EO Criteria, above) constitutes an element occurrence regardless of separation distance. Multiple caves within a single hydrological cave system are each considered separately. Caves with multiple entrances and passages known to be connected, but with connecting passages too small or unsafe for human entry shall be treated as a single element occurrence when the non-negotiable portion of the cave is thought to be less than approximately 300 m linear length. Species known to occur in caves include: Amnicola cora, Antrobia spp., Antrobis spp., Antroselates spp., Dasyscias spp., Fontigens aldrichi, F. antroecetes, F. bottimeri, F. morrisoni, F. nickliniana, F. orolibas, F. prosperpina, F. tartarea, F. turritella, Holsingeria spp., Phreatodrobia spp., Stygopyrgus spp.
Separation Justification: Freshwater snails have adapted to most North American habitats including permanent standing, intermittent, and flowing waters. As a whole, pulmonates (previously Subclass Pulmonata) are better dispersers than prosobranchs (previously Subclass Prosobranchia). Pulmonates adapt better to changing temperature and oxygen concentration, resist desiccation better (use pulmonary respiration, store excreted nitrogen as urea, aestivate), and have faster crawling rates (including righting response and actual movement rate) than prosobranchs (Brown et al., 1998). Some species are more tolerant to adverse habitat conditions such as high pollution levels (e.g. Physella spp.), high altitude [e.g. Acroloxus coloradensis (Henderson, 1930)], underground cave pools and springs (e.g. Fontigens spp., Phreatodrobia spp.) and hot springs (e.g. Pyrgulopsis spp.).

Precise geographic distribution of many American freshwater snails is not known but presumably reflects past geological, geographic, and climatic change (Smith, 1989). Movements between isolated or inaccessible portions of water bodies is possible but dependent on outside, passive processes (e.g. rafting, periodic flooding, transport by vertebrates, introduction by humans). Long-distance dispersal is generally not considered when assigning separation distances as otherwise impracticably large separation distances would result.

Several factors contribute to limiting freshwater snail distribution but none apply across diverse habitats or taxa. Approximately 95% of all freshwater gastropods are restricted to waters with calcium concentrations greater than 3 mg/liter (Brown, 1991; for exceptions see Jokinen, 1983). Calcium uptake for shell construction requires energy expenditure (active transport) when calcium concentration is low, but is passive at higher concentrations (Greenaway, 1971). Typically, no known biotic or abiotic factors consistently limit the abundance or distribution of freshwater gastropods among sites (DeVries et al., 2003). At specific localities, limiting factors may include hardness, acidity, dissolved oxygen, salinity, high temperature, and food availability as associated with depth (Smith, 1989). Most species and the largest populations occur in hard, alkaline waters with normal range 20-180 ppm (Shoup, 1943; Harman, 1974). Snails are uncommon in habitats with surface acidity greater than pH 5 (see also Jokinen, 1983). Dissolved oxygen limits diversity so severely polluted waters (oxygen consumed by algae blooms) are often devoid of freshwater snails excepting pollution tolerant species. Because pulmonates can utilize atmospheric oxygen, they can exist under anaerobic conditions for longer time periods (Harman and Berg, 1971; Harman, 1974; McMahon, 1983). High salinity is limiting to freshwater gastropods and inland saline lakes generally lack an associated snail fauna. Most species (excepting hot springs species) are intolerant of temperatures greater than 45ºC (McDonald, 1969; van der Schalie and Berry, 1973), a condition rarely occurring naturally. Lower temperatures are less limiting as snails have been found foraging in ice-covered waters (Harman and Berg, 1971; Harman, 1974). Most species live in the shallows, (depths less than 3 m) where food abundance is greatest. As a result, drastic water fluctuations (draw-downs) may cause declines in snail populations (Hunt and Jones, 1972).

Any contiguous, occupied stretch of suitable flowing water habitat 2 km long or greater is considered an element occurrence. Two km was chosen based upon the limited active movement capabilities of most benthic invertebrates and observed home range of freshwater snails (J. Cordeiro, personal observation) as well as the relatively short life span of most species (five years for most stream species and two years for most pond species).

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Prosobranchs: Neritidae: Neritina; Viviparidae: Campeloma, Cipangopaludina, Lioplax, Tulotoma, Viviparus; Ampullariidae: Marisa, Pomacea; Pleuroceridae: Elimia, Goniobasis, Gyrotoma, Io, Juga, Leptoxis, Lithasia, Pleurocera; Thiaridae: Melanoides, Tarebia; Bithyniidae: Bithynia; Hydrobiidae: Amnicola, Antrobia, Antrorbis, Antroselates, Aphaostracon, Balconorbis, Birgella, Cincinnatia, Clappia, Cochliopa, Cochliopina, Colligyrus, Dasyscias, Eremopyrgus, Floridiscrobs, Fluminicola, Fontelicella, Fontigens, Gillia, Heleobops, Holsingeria, Hoyia, Hydrobia, Lepyrium, Littoridina, Littoridinops, Lyogyrus, Notogillia, Onobops, Paludina, Phreatoceras, Phreatodrobia, Potamopyrgus, Pristinicola, Probythinella, Pyrgophorus, Pyrgulopsis, Rhapinema, Somatogyrus, Spilochlamys, Spurwinkia, Stiobia, Stygopyrgus, Taylorconcha, Texadina, Texapyrgu, Tryonia; Assimineidae: Assiminea; Pomatiopsidae: Pomatiopsis, Heterostropha; Valvatidae: Valvata

Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 17Feb2015
NatureServe Conservation Status Factors Author: Cordeiro, J. (2008); Sears, N. (2015)
Element Ecology & Life History Edition Date: 17Mar2008
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).

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