The rain beetles are a group 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 insects. The Coleoptera, with about 400,000 describ ...
s whose extant species are found only in the far west of
North America.
They spend most of their lives underground, emerging in response to rain or snow, thus the common name. Formerly classified in the
Scarabaeidae
The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...
(and later the
Geotrupidae
Geotrupidae (from Greek γῆ ''(gē)'', earth, and τρῡπητής ''(trȳpētēs)'', borer) is a family of beetles in the order Coleoptera. They are commonly called earth-boring dung beetles or dor beetles. Most excavate burrows in which t ...
), they are currently assigned to their own family Pleocomidae, considered the
sister group to all the remaining families of
Scarabaeoidea
Scarabaeoidea is a superfamily of beetles, the only subgroup of the infraorder Scarabaeiformia. Around 35,000 species are placed in this superfamily and some 200 new species are described each year. Its constituent families are also undergoing r ...
. The family contains a single
extant genus, ''
Pleocoma'', and two
extinct genera, ''Cretocoma'', described in 2002 from
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
deposits in
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
,
and ''
Proteroscarabeus'' of Late Cretaceous
China.
[Krell, Frank-Thorsten. "The fossil record of Mesozoic and Tertiary Scarabaeoidea (Coleoptera: Polyphaga)." Invertebrate Systematics 14.6 (2000): 871-905.]
Extant members of ''
Pleocoma'' are known from extreme southern
Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
, throughout the mountains of
Oregon
Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...
and
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, and into the extreme north of
Baja California
Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
.
References
*
External links
*
{{Taxonbar, from=Q311154
Scarabaeiformia