{{Short description|Species of gastropod}} {{Speciesbox | name = Flat pebblesnail | image = Lepyrium showalteri shell.jpg | image_caption = An 1870 drawing of the shell of ''Lepyrium showalteri'' | status = VU | status_system = IUCN2.3 | status_ref = <ref name="iucn status 16 November 2021">{{cite iucn |author=Bogan, A.E. |date=1996 |title=''Lepyrium showalteri'' |volume=1996 |article-number=e.T11803A3309572 |doi=10.2305/IUCN.UK.1996.RLTS.T11803A3309572.en |access-date=16 November 2021}}</ref> | status2 = G1 | status2_system = TNC | status2_ref = <ref name=NS>{{cite NatureServe |id=2.110506 |title=''Lepyrium showalteri'' |access-date=5 April 2026}}</ref> | display_parents = 2 | parent_authority = Dall, 1896<ref name="Dall 1896">Dall W. H. <!--June-->(1896). "Note on ''Neritina schowalteri'' Lea". ''The Nautilus'' '''10'''(2): [https://archive.org/stream/nautilus10amer#page/12/mode/2up 13]-15.</ref> | taxon = Lepyrium showalteri | authority = (Lea, 1861)<ref name="Lea">Lea I. (1861). "Description of a new species of ''NERITINA'', from Coosa River, Alabama". ''Proceedings of the Academy of Natural Sciences of Philadelphia'' '''13'''(1861): [https://archive.org/stream/proceedingsofaca13acad#page/54/mode/2up page 55].</ref> | synonyms = {{Species list |Lepyrium showalteri cahawbensis|Pilsbry, 1906 |Neritina showalterii|Lea, 1861}} | synonyms_ref = <ref name=WoRMS>{{cite WoRMS |id=887041 |title=''Lepyrium showalterii'' (I. Lea, 1861) |db=mollusc |access-date=12 April 2026}}</ref> }}
The '''flat pebblesnail''' (''Lepyrium showalteri'') is a species of freshwater snail, an aquatic gastropod mollusk in the family Lithoglyphidae.<ref name="Bouchet 2005">{{Bouchet 2005}}</ref>
This species is endemic to the United States. This snail has been listed as endangered on the United States Fish and Wildlife Service list of endangered species since October 28, 1998.<ref>U.S. Fish & Wildlife Service. [http://ecos.fws.gov/speciesProfile/SpeciesReport.do?spcode=G07F "Species profile Flat pebblesnail (''Lepyrium showalteri'')"]. Accessed 27 November 2008.</ref>
''Lepyrium showalteri'' is the only species in the genus '''''Lepyrium'''''.<ref name="Thompson 1984"/> ''Lepyrium showalteri'' is the type species of the genus ''Lepyrium''.<ref name="Dall 1896"/> Lepyriidae is a synonym of Lithoglyphinae.<ref name="Bouchet 2005"/>
[[File:Lepyrium showalteri.jpg|thumb|left|Flat pebblesnail (Lepyrium showalteri) shells from the Cahaba River]]
== Description == The flat pebblesnail is a small snail in the family Lithoglyphidae; however, the species has a large and distinctive-looking shell. This snail's shell is also distinguished by its depressed spire and expanded, flattened body whorl. The shells are ovate in outline, flattened, and grow to {{convert|3.5|to|4.4|mm|in|abbr=on}} high and 4 to {{convert|5|mm|in|abbr=on}} wide. The umbilical area is imperforate (no opening), and there are 2 to 3 whorls which rapidly expand.<ref name="plan"/>
The anatomy of this species was described in detail by Thompson in 1984.<ref name="Thompson 1984">Thompson F. G. (1984). "North American freshwater snail general of the hydrobiid subfamily Lithoglyphinae". ''Malacologia'' '''25'''(1): [https://archive.org/stream/malacologia251984inst#page/108/mode/2up 109]-141.</ref>
== Original description == Species ''Lepyrium showalteri'' was originally described as ''Neritina showalteri'' by Isaac Lea in 1861.<ref name="Lea"/>
Lea's original text (the type description) reads as follows:
{{blockquote| Neritina Showalterii. Testâ, laevi, rotundatâ, diaphanâ, luteo-corneâ; spirâ valdè depressâ; suturis leviter impressis; anfractibus trinis, inflatis; aperturâ semirotundâ; labio dilatato, albo, incrassato, edentulo et incurvato; labro dilatato, tenui, margine acuto.
Hab. Coosa River, ten miles above Fort William, Shelby Co., Alabama. E. R. Showalter, M. D.
Remarks. The discovery of this shell by Dr. Showalter marks the first notice of the genus ''Neritina'' being observed in our fresh waters. His very close observation and active investigation of the waters of central and northern Alabama, have enabled him to lay the naturalists of this country under many obligations by new discoveries, and this is certainly one of much importance. We now see for the first time that this genus, which is common in Europe, Africa, Asia, South America and the West Indies, also inhabits our southern fresh waters. I have great pleasure in naming the species after the discoverer.
This species is not closely allied to any which has come under my notice. It is more rotund than usual, has a clear horn-colored epidermis, smooth and shining; the substance of the shell so thin as to permit the column to be visible through it.
It is to be regretted that among the four specimens sent to me by Dr. Showalter, neither had an operculum. The soft parts of the animal have not yet been observed. }}
== Distribution == This species is endemic to Alabama in the United States. It was historically known from:<ref name="Thompson 1984"/> * the mainstem Coosa River in Shelby County and Talladega County, Alabama; * the Cahaba River in Bibb and Dallas County, Alabama; * and the Little Cahaba River in Bibb County, Alabama.
The flat pebblesnail has not been found in the Coosa River portion of its range since the construction of the Lay Dam and Logan Martin Dam, and recent survey efforts have failed to locate any surviving populations outside of the Cahaba River drainage.<ref>Bogan A. E. & Pierson J. M. (1993). ''Survey of the aquatic gastropods of the Coosa River Basin, Alabama: 1992''. Alabama Natural Heritage Program. Contract Number 1923.</ref><ref name="Bogan 1993b">Bogan A. E. & Pierson J. M. (1993). ''Survey of the aquatic gastropods of the Cahaba River Basin, Alabama: 1992''. Alabama Natural Heritage Program. Contract Number 1922.</ref><ref>McGregor S. W., Sheppard T. E., Richardson T. D. & Fitzpatrick J. F. Jr. (1996). ''A survey of the primary tributaries of the Alabama and lower Tombigbee rivers for listed and candidate species of freshwater mussels, snails, and crayfish, 1994-1996''. Geological Survey of Alabama. 29 pp.</ref><ref>U.S. Fish and Wildlife Service Field Records, Jackson, Mississippi, 1989-1996; Bogan in litt. (1995). M. Pierson Field Records, Calera, Alabama, in litt., 1993-1994; J. Garner, pers. comm. (1996); J. Johnson, in litt. (1996); In: U.S. Fish and Wildlife Service (2005). [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp., page 5-6.</ref>
The flat pebblesnail is currently known from one site on the Little Cahaba River, Bibb County, and from a single shoal series on the Cahaba River above the Fall Line, Shelby County, Alabama.<ref name="Bogan 1993b"/> <gallery> File:Map of Alabama highlighting Bibb County.svg|Bibb County, Alabama (marked red) where the species is found in the Little Cahaba River. File:Map of Alabama highlighting Shelby County.svg|Shelby County, Alabama (marked red) where the species is known from the Cahaba River. </gallery>
== Ecology == Little is known of the natural history of this species. The flat pebblesnail is found attached to clean, smooth stones in rapid currents of river shoals.<ref name="plan"/> The eggs are laid in capsules on hard surfaces.<ref name="Thompson 1984"/> The life span appears to be 1 year.<ref>Johnson P. pers. comm. (2005). In: U.S. Fish and Wildlife Service (2005). [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp., page 5-6.</ref>
== References == This article incorporates public domain text from the reference<ref name="Lea"/> and a public domain work of the United States Government from the reference<ref name="plan">U.S. Fish and Wildlife Service (2005). [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp., page 5-6.</ref> {{Reflist|30em}}
== External links == *Tryon G. W. (1888–1889) ''Manual of Conchology, structural and systematic, with illustrations of the species''. '''10''': [https://archive.org/stream/manualofconcholo110tryo#page/52/mode/2up 53], [https://archive.org/stream/manualofconcholo110tryo#page/n360/mode/1up plate 17], figure 81–82.
{{Taxonbar|from=Q3173245}}
Category:Gastropods described in 1861 Category:Endemic molluscs of the United States Category:Endemic fauna of Alabama Category:Lithoglyphidae Category:Taxonomy articles created by Polbot Category:ESA endangered species