''Amnicola walkeri'', common name Canadian duskysnail, 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 ...

, 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 ...

mollusk 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 e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Amnicolidae Amnicolidae is a family of small freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the superfamily Rissooidea. This family is in the clade Littorinimorpha (according to the taxonomy of the Gastropoda by Bouchet & R ...

. The name is in honor of Mr.

Bryant Walker Bryant Walker (1856–1936) was an American malacologist who specialized in the non-marine Mollusca. He mainly studied the freshwater mollusks of the USA, in particular those of Michigan. He published many papers on the Unionida, an order of fres ...

Shell description

The shell is thin, narrowly umbilicate, conic, shaped like '' Lyogyrus brownii'' Carpenter. The color of the shell is slightly yellowish corneous. The shell is thin, smooth, with faint growth-lines. The shell has 4

whorls A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral d ...

that are very convex and separated by deeply constricting sutures. The last whorl is rounded below. The apex is obtuse. The

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 ...

is oblique, rather small, mainly basal, a little longer than wide, but nearly circular. The inner margin is a trifle straightened above. The peristome is continuous, in contact with the preceding whorl for an extremely short distance above. Operculum is amnicoloid. The width of the shell is 2-2.125 mm. The height of the shell is 2.33–3 mm. The width of aperture is 1-1.125 mm. The height of aperture is 1.08-1.25 mm.

Anatomy

The

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

is amnicoloid.

Distribution

Type locality is

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...

at High Island Harbor, Beaver Island, at 10 meters depth. Other localities include: Reed's Lake,

Grand Rapids Grand Rapids is a city and county seat of Kent County in the U.S. state of Michigan. At the 2020 census, the city had a population of 198,917 which ranks it as the second most-populated city in the state after Detroit. Grand Rapids is the ...

, Michigan; River Rouge, Wayne County, Michigan.

References

This article incorporates public domain text from reference. {{DEFAULTSORT:Amnicola Walkeri Amnicola Gastropods described in 1898