''Sphaerius'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on

algae Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from ...

; they occur on all continents except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

. Three species occur in 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 U.S. state, states, a Washington, D.C., federal district, five ma ...

. The overall form of the beetle is convex, glossy, dark brown or black with some markings possible. The head is prominent, with relatively large eyes set far apart, and

capitate The capitate bone is a bone in the human wrist found in the center of the carpal bone region, located at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone (the middle finger) and forms the third carpomet ...

antennae. Total length ranges from . The beetles occur in a variety of damp environments, including mud, under stones, among plant roots and leaf litter, and in mosses in bogs. They store some air underneath their

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs ( Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes altern ...

. Females produce a single large egg at a time. The family used to be known as "Sphaeriidae", but the name was preoccupied by a family of freshwater

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two sh ...

s. The name was inappropriately replaced with "Microsporidae" (by changing the genus name to ''Microsporus''), but this act has been superseded by a return to the use of ''Sphaerius'' and a reformation of the family name as Sphaeriusidae. The position of the family within Coleoptera has also changed a number of times. Ross H. Arnett, Jr. and Michael C. Thomas, ''

American Beetles ''American Beetles'' is the single most comprehensive description of the beetles of North America north of the tropical area of Mexico. It was started by Ross H. Arnett, Jr. as an update of his classic ''The Beetles of the United States''; alon ...

'' (CRC Press, 2001)

Species

*'' Sphaerius acaroides'' *''

Sphaerius africanus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...

'' *''

Sphaerius alticola ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...

'' *'' Sphaerius coenensis'' *''

Sphaerius coomani ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...

'' *''

Sphaerius cribratus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ...

'' *''

Sphaerius favosus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ...

'' *'' Sphaerius gustavlohsei'' *'' Sphaerius hispanicus'' *'' Sphaerius humicola'' *'' Sphaerius laeviventris'' *'' Sphaerius madecassus'' *'' Sphaerius minutus'' *'' Sphaerius politus'' *'' Sphaerius obsoletus'' *'' Sphaerius ovensensis'' *'' Sphaerius papulosus'' *'' Sphaerius perlaevis'' *''

Sphaerius scutellaris ''Orthoperus scutellaris'' is a species of minute hooded beetle in the family Corylophidae. It is found in North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is ...

'' *''

Sphaerius silvicola ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...

'' *''

Sphaerius spississimus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ...

'' *''

Sphaerius tesselatus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ...

'' *''

Sphaerius texanus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ...

'' *''

Sphaerius tropicus ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...

Fossil Sphaeriusidae

* †''Burmasporum'' Kirejtshuk 2009

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. ...

, Myanmar, Cenomanian

References

External links

Sphaeriusidae
Tree of Life {{Taxonbar, from1=Q606681, from2=Q16209130 Myxophaga genera Taxa named by Joseph Waltl