''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 nom ...

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; 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 cont ...

. 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 states, a federal district, five major unincorporated territori ...

. 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 alterna ...

. 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 shel ...

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. Ross Harold Arnett Jr. (April 13, 1919 – July 16, 1999) was an American entomologist noted for his studies of beetles, and as founder of the ''Coleopterist's Bulletin''. Born in Medina, New York, he was a star student at Cornell University, wher ...

and Michael C. Thomas, '' American Beetles'' (CRC Press, 2001)

Species

*''

Sphaerius acaroides ''Sphaerius acaroides'' is a species of 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 i ...

'' *'' Sphaerius africanus'' *'' Sphaerius alticola'' *'' Sphaerius coenensis'' *'' Sphaerius coomani'' *'' Sphaerius cribratus'' *'' Sphaerius favosus'' *'' Sphaerius gustavlohsei'' *'' Sphaerius hispanicus'' *'' Sphaerius humicola'' *'' Sphaerius laeviventris'' *'' Sphaerius madecassus'' *'' Sphaerius minutus'' *'' Sphaerius politus'' *'' Sphaerius obsoletus'' *'' Sphaerius ovensensis'' *'' Sphaerius papulosus'' *'' Sphaerius perlaevis'' *'' Sphaerius scutellaris'' *'' Sphaerius silvicola'' *'' Sphaerius spississimus'' *'' Sphaerius tesselatus'' *'' Sphaerius texanus'' *'' Sphaerius tropicus''

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. The ...

, Myanmar, Cenomanian

References

External links

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