''Laevapex fuscus'', the dusky ancylid, 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 ...

of small,

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

, air-breathing

limpet Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" descended indep ...

, an aquatic

pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...

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 ...

micromollusc A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also r ...

in the family

Planorbidae Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod molluscs. Unlike most molluscs, the blood of ram's horn snails contains iron-based hemoglobin instea ...

, the ram's horn snails and their allies.

Geographic distribution

''L. fuscus'' is found throughout

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

east of the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

, except for mountainous areas. It has been recorded in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, 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 ...

Jamaica Jamaica (; ) is an island country situated in the Caribbean Sea. Spanning in area, it is the third-largest island of the Greater Antilles and the Caribbean (after Cuba and Hispaniola). Jamaica lies about south of Cuba, and west of His ...

and

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

Description

''L. fuscus'' was originally described as ''Ancylus fuscus'' in 1841 by

Charles Baker Adams Charles Baker Adams (January 11, 1814 – January 19, 1853) was an American educator and naturalist. Biography He was born in Dorchester, Massachusetts in 1814, the son of Charles J. Adams and Hannah Baker. He graduated from Phillips Academy i ...

: :"''

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 o ...

'' thin, transparent without the epidermis, not much elevated, elliptical, moderately curved at the sides; ''epidermis'' brown, visible through the shell, giving it the appearance of having the same color, thick, rough, slightly extending beyond the margin of the shell; ''

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...

'' obtuse, moderately prominent, scarcely behind the middle, inclining to the right, so as to have only two fifths of the width on that side. :Length, , width, ; height, ."

Habitat and ecology

''L. fuscus'' generally occurs in

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s, preferring calmer waters than other ancylid genera. Simple annual (

univoltine Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. ...

) and two-generation per year (

bivoltine Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. ...

) life cycles have been reported in New York populations of ''L. fuscus''. The bioenergetic data collected for the species suggest that its reproductive effort is in line with expectation from adult weight, and hence that its life history strategy is undifferentiated. The species is functionally protandric, despite being one of the more specialised of higher

limnic Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

snails. ''L. fuscus'' has been observed attached to the wings or hemelytra of the water bug species '' Belostoma flumineum'' (

Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...

Belostomatidae Belostomatidae is a family of freshwater hemipteran insects known as giant water bugs or colloquially as toe-biters, Indian toe-biters, electric-light bugs, alligator ticks, or alligator fleas (in Florida). They are the largest insects in the or ...

). This observation suggests that belostomatids might serve as a mode of transport and a passive dispersal agent for ''L. fuscus'' and other ancylid species.

References

{{Taxonbar, from=Q3691592 Planorbidae Molluscs of North America Freshwater animals of North America Gastropods described in 1841 Taxa named by Charles Baker Adams

Geographic distribution

Description

Habitat and ecology

See also

References