''Leptoxis ampla'',

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

the round rocksnail, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...

with a

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

and an operculum, an aquatic

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Pleuroceridae Pleuroceridae, common name pleurocerids, is a family of small to medium-sized freshwater snails, aquatic gilled gastropod mollusks in the superfamily Cerithioidea.These snails have an operculum and typically a robust high-spired shell. Reprodu ...

. This species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, specifically the state of

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

. The snail has been listed as threatened on the

United States Fish and Wildlife Service list of endangered species This is a list of the bird and mammal species and subspecies described as endangered by the United States Fish and Wildlife Service. It contains species and subspecies not only in the U.S. and its territories, but also those only found in other par ...

since 28 October 1998. ''Leptoxis ampla'' is a vulnerable species according to the IUCN Red list.

Description

The round rocksnail is a pleurocerid snail and its

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...

grows to about 20 mm (0.8 in) in length. The shell is subglobose, with an ovately rounded

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

. The

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

is shouldered at the suture, and may be ornamented with folds or plicae. Color may be yellow, dark brown, or olive green, usually with four entire or broken bands.Goodrich C. (1922). "The Anculosae of the Alabama River Drainage". ''Miscellaneous Publications'', Museum of Zoology, University of Michigan (7): 1–57. Lydeard et al. (1997) found slight differences in

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...

between the

painted rocksnail The painted rocksnail (''Leptoxis coosaensis,'' formerly ''Leptoxis taeniata'') is a species of freshwater snail with a gill and an operculum (gastropod), operculum, an aquatic animal, aquatic gastropod mollusk in the family Pleuroceridae. This ...

and the round rocksnail, and considered them to be

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

. Following analysis by

allozyme Alloenzymes (or also called allozymes) are variant forms of an enzyme which differ structurally but not functionally from other allozymes coded for by different alleles at the same locus. These are opposed to isozymes, which are enzymes that perfo ...

electrophoresis Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric fie ...

on these same species, Dillon speculated that the two species represented isolated

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

s belonging to a single species. The two species are geographically separated, with the painted rocksnail inhabiting

Coosa River The Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 27, 2011 ...

tributaries, and the round rocksnail inhabiting the

Cahaba River The Cahaba River is the longest substantially free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. It is a major tributary of the Alabama River and part of the larger Mobile River basin. ...

drainage. Both species are currently recognized by the malacological community.

Distribution

The round rocksnail was historically found in the

and the

Little Cahaba River Little is a synonym for small size and may refer to: Arts and entertainment * ''Little'' (album), 1990 debut album of Vic Chesnutt * ''Little'' (film), 2019 American comedy film *The Littles, a series of children's novels by American author John P ...

Bibb County, Alabama Bibb County is a county in the central portion of the U.S. state of Alabama. The county is included in the ARC's definition of Appalachia. As of the 24th decennial 2020 census, its population was 22,293. The county seat is Centreville. The ...

; and the

Elmore County, Alabama Elmore County is a county located in the east central portion of the U.S. state of Alabama. As of the 2020 census, the population was 87,977. Its county seat is Wetumpka. Its name is in honor of General John A. Elmore. Elmore County is part o ...

, and tributaries—Big Canoe and Kelly's creeks, St. Clair County, Alabama;

Ohatchee Creek Ohatchee (inc. 1956) is a town in Calhoun County, Alabama, United States. At the 2020 census, the population was 1,157. It is included in the Anniston–Oxford, Alabama Metropolitan Statistical Area. History Andrew Jackson used the area aro ...

Calhoun County, Alabama Calhoun County is a County (United States), county in the east central part of the U.S. state of Alabama. As of the 2020 United States census, 2020 census, the population was 116,441. Its county seat is Anniston, Alabama, Anniston. It was named ...

; Yellowleaf Creek,

Shelby County, Alabama Shelby County is located in the Central Alabama, central portion of the U.S. state of Alabama. As of the 2020 United States census, 2020 census the population was 223,024. The county seat is Columbiana, Alabama, Columbiana. The largest city is A ...

; and

Waxahatchee Creek Waxahatchee Creek is a tributary of the lower Coosa River near Shelby, Alabama. It forms the southeastern border between Shelby County and Chilton County, where it is crossed by Alabama State Route 145. The lower reaches of Waxahatchee Creek are ...

, Shelby/ Chilton counties, Alabama. The type locality is Alabama. The round rocksnail is currently known from a shoal series in the Cahaba River, Bibb and Shelby counties, Alabama, and from the lower reach of the Little Cahaba River, and the lower reaches of Shade and Six-mile creeks in Bibb County, Alabama.

Reasons for the decline

The round rocksnail has disappeared from more than 90 percent of its historic range. The curtailment of habitat and range for this (and few other snail species) species in the

Mobile Mobile may refer to: Places * Mobile, Alabama, a U.S. port city * Mobile County, Alabama * Mobile, Arizona, a small town near Phoenix, U.S. * Mobile, Newfoundland and Labrador Arts, entertainment, and media Music Groups and labels * Mobile ( ...

Basin's larger rivers (Cahaba River, Coosa River and its tributaries for round rocksnail) is primarily due to extensive construction of

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, a ...

s, and the subsequent

inundation A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrolog ...

of the snail's shoal habitats by the impounded waters. This snail has disappeared from all portions of its historic habitats that have been impounded by dams. Dams change such areas by eliminating or reducing currents, and thus allowing sediments to accumulate on inundated channel habitats. Impounded waters also experience changes in water chemistry, which could affect survival or reproduction of riverine snails. For example, many reservoirs in the Basin currently experience eutrophic (enrichment of a water body with nutrients) conditions, and chronically low dissolved oxygen levels. Such physical and chemical changes can affect feeding, respiration, and reproduction of these riffle and shoal snail species.

Ecology

Habitat

Rocksnails are gill breathing snails found attached to cobble, gravel, or other hard substrates in the strong currents of riffles and shoals.

Life cycle

Adult rocksnails move very little, and females probably glue their eggs to stones in the same habitat. Longevity in the round rocksnail is unknown; however, it was reported as having a short life span (less than 2 years) in a Tennessee River rocksnail.Heller J. (1990). "Longevity in molluscs". ''

Malacologia ''Malacologia'' is a peer-reviewed scientific journal in the field of malacology, the study of mollusks. The journal publishes articles in the fields of molluscan systematics, ecology, population ecology, genetics, molecular genetics, evolution, an ...

'' 31(2)
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References

This article incorporates public domain text (a

public domain The public domain (PD) consists of all the creative work A creative work is a manifestation of creative effort including fine artwork (sculpture, paintings, drawing, sketching, performance art), dance, writing (literature), filmmaking, ...

work of the United States Government A work of the United States government, is defined by the United States copyright law, as "a work prepared by an officer or employee of the United States Government as part of that person's official duties." "A 'work of the United States Governmen ...

) from the reference.

U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with oth ...

. (2005)
''Recovery Plan for 6 Mobile River Basin Aquatic Snails''
U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp. pages 11–12 and page 15.

External links

{{Taxonbar, from=Q3167737 ampla Molluscs of the United States Gastropods described in 1855 Taxonomy articles created by Polbot ESA threatened species