Flat pebblesnail
Encyclopedia
The flat pebblesnail, scientific name Lepyrium showalteri, is a species
of freshwater snail
, an aquatic
gastropod mollusk in the family Lithoglyphidae
.
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.
Lepyrium showalteri is the only species in the genus Lepyrium. Lepyrium showalteri is the type species
of the genus Lepyrium. Lepyriidae is a synonym of Lithoglyphinae.
. 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 3.5 to 4.4 mm (0.1 to 0.2 in) high and 4 to 5 mm (0.2 in) wide. The umbilical area is imperforate (no opening), and there are 2 to 3 whorls
which rapidly expand.
The anatomy of this species was described in detail by Thompson in 1984.
in 1861.
Lea's original text (the type description) reads as follows:
in the United States. It was historically known from:
The flat pebblesnail has not been found in the Coosa River portion of its range since the construction of the Lay and Logan Martin Dams, and recent survey efforts have failed to locate any surviving populations outside of the Cahaba River drainage.
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
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod mollusk in the family Lithoglyphidae
Lithoglyphidae
Lithoglyphidae is a family of small freshwater snails with gills and an operculum, aquatic gastropod mollusks.This family is in the superfamily Rissooidea and in the clade Littorinimorpha .- Taxonomy :Taylor , Ponder & Warén and Kabat & Hershler considered this taxon as a subfamily...
.
This species is endemic to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. This snail has been listed as endangered on the United States Fish and Wildlife Service list of endangered species
United States Fish and Wildlife Service list of endangered species
This list contains only the bird and mammal species described as endangered by the United States Fish and Wildlife Service. It contains species not only in the U.S. and its territories, but also species only found abroad. It does not contain fish, amphibians, reptiles, plants, or invertebrates,...
since October 28, 1998.
Lepyrium showalteri is the only species in the genus Lepyrium. Lepyrium showalteri is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Lepyrium. Lepyriidae is a synonym of Lithoglyphinae.
Description
The flat pebblesnail is a small snail in the family Lithoglyphidae; however, the species has a large and distinctive-looking shellGastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
. This snail's shell is also distinguished by its depressed spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
and expanded, flattened body whorl
Body whorl
Body whorl is part of the morphology of a coiled gastropod mollusk.- In gastropods :In gastropods, the body whorl, or last whorl, is the most recently-formed and largest whorl of a spiral or helical shell, terminating in the aperture...
. The shells are ovate in outline, flattened, and grow to 3.5 to 4.4 mm (0.1 to 0.2 in) high and 4 to 5 mm (0.2 in) wide. The umbilical area is imperforate (no opening), and there are 2 to 3 whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
which rapidly expand.
The anatomy of this species was described in detail by Thompson in 1984.
Original description
Species Lepyrium showalteri was originally described as Neritina showalteri by Isaac LeaIsaac Lea
Isaac Lea was an American conchologist, geologist, and businessman, who was born in Wilmington, Delaware.-Life:...
in 1861.
Lea's original text (the type description) reads as follows:
Distribution
This species is endemic to AlabamaAlabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
in the United States. It was historically known from:
- the mainstem Coosa RiverCoosa RiverThe Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long altogether.The Coosa River is one of Alabama's most developed rivers...
in Shelby CountyShelby County, AlabamaShelby County is a county of the U.S. state of Alabama and a part of the Birmingham–Hoover–Cullman Combined Statistical Area. It is named in honor of Isaac Shelby, Governor of Kentucky. The county seat of Shelby County is Columbiana. As of 2010 U.S. Census the population was 195,085. Shelby...
and Talladega County, AlabamaTalladega County, AlabamaTalladega County is a county of the U.S. state of Alabama. Talladega is a Muscogee Native American word derived from TVLVTEKE, which means "border town." As of 2010, the population was 82,291...
; - the Cahaba RiverCahaba RiverThe Cahaba River is the longest free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. The Cahaba River is a major tributary of the Alabama River and part of the larger Mobile River Basin...
in BibbBibb County, AlabamaBibb County is a county in the U.S. state of Alabama. Its name is in honor of William W. Bibb, the first Governor of Alabama. As of 2010 the population was 22,915. The county seat is Centreville...
and Dallas County, AlabamaDallas County, AlabamaDallas County is a county of the U.S. state of Alabama. Its name is in honor of United States Secretary of the Treasury Alexander J. Dallas. The county seat is Selma.- History :...
; - 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 and Logan Martin Dams, and recent survey efforts have failed to locate any surviving populations outside of the Cahaba River drainage.
The flat pebblesnail is currently known from one site on the Little Cahaba River, Bibb County
Bibb County, Alabama
Bibb County is a county in the U.S. state of Alabama. Its name is in honor of William W. Bibb, the first Governor of Alabama. As of 2010 the population was 22,915. The county seat is Centreville...
, and from a single shoal series on the Cahaba River
Cahaba River
The Cahaba River is the longest free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. The Cahaba River is a major tributary of the Alabama River and part of the larger Mobile River Basin...
above the Fall Line, Shelby County, Alabama
Shelby County, Alabama
Shelby County is a county of the U.S. state of Alabama and a part of the Birmingham–Hoover–Cullman Combined Statistical Area. It is named in honor of Isaac Shelby, Governor of Kentucky. The county seat of Shelby County is Columbiana. As of 2010 U.S. Census the population was 195,085. Shelby...
.
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. The eggs are laid in capsules on hard surfaces. The life span appears to be 1 year.External links
- Tryon G. W.George Washington TryonGeorge Washington Tryon, Jr. was an American malacologist who worked at the Academy of Natural Sciences in Philadelphia.- Biography :George Washington Tryon was the son of Edward K. Tryon and Adeline Savidt...
(1888-1889) Manual of Conchology, structural and systematic, with illustrations of the species. 10: 53, plate 17, figure 81-82.