'Plectreuridae, often called Plectreurid spiders, are a small spider family confined to the North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n desert

Desert

A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

s and the island of Cuba

Cuba

The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...

. Only two living genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 are known - the nominate genus Plectreurys and Kibramoa. In the past, the family was more widespread, with the Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 genus Eoplectreurys

Eoplectreurys

Eoplectreurys is an extinct monotypic genus of spider from the family Plectreuridae, with a sole species, Eoplectreurys gertschi...

 known from China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, the Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 Palaeoplectreurys baltica from Baltic amber

Baltic amber

The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite, with about 80% of the world's known amber found there. It dates from 44 million years ago...

 and the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 Plectreurys pittfieldi from Dominican amber

Dominican amber

Dominican amber is amber from the Dominican Republic. Resin from the extinct species Hymenaea protera is the source of Dominican amber and probably of most amber found in the tropics....

.

These ecribellate

Cribellum

The cribellum is a silk spinning organ found in certain spiders. Unlike normal spinnerets, the cribellum consists of one or more plates covered in thousands of tiny spigots. These spigots produce extremely fine fibers which are combed out by the spider's calamistrum, producing silk with a wooly...

 (lacking a plate-like wooly silk

Spider silk

Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...

-producing structure anterior to the spinnerets on the venter), haplogyne spiders build haphazard web

Spider web

A spider web, spiderweb, spider's web or cobweb is a device built by a spider out of proteinaceous spider silk extruded from its spinnerets....

s under rocks and dead cacti

Cactus

A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

. Relatively little is known of their biology. Unlike the sicariids, scytodids and diguetids, to which they are related, they have eight eyes. In appearance females of Plectreurys resemble those of the larger species of the cribellate Filistatidae. They differ in their eye arrangement and in having the first femora (third leg segment from the body) bowed.

Species

†

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

Eoplectreurys

Eoplectreurys

Eoplectreurys is an extinct monotypic genus of spider from the family Plectreuridae, with a sole species, Eoplectreurys gertschi...

 Selden & Huang, 2010

• †Eoplectreurys gertschi
  Eoplectreurys
  Eoplectreurys is an extinct monotypic genus of spider from the family Plectreuridae, with a sole species, Eoplectreurys gertschi...
  
   Selden & Huang, 2010 (Middle Jurassic, China)

Kibramoa Chamberlin, 1924

• Kibramoa guapa Gertsch
  Willis J. Gertsch
  Willis John Gertsch was an American arachnologist. He classified a number of species, including the Brown recluse spider and the Tooth cave spider....
  
  , 1958 (USA, Mexico)
• Kibramoa hermani Chamberlin
  Ralph Vary Chamberlin
  Ralph Vary Chamberlin was an American zoologist from Salt Lake City, Utah. He received his PhD from Cornell University in 1904. He was a professor of zoology at Brigham Young University from 1908-1911, and at the University of Utah from 1925-1938....
  
   & Ivie
  Wilton Ivie
  Wilton Ivie was an American entomologist, who descriped Arachnida-species. . He was employed by the American Museum of Natural History in New York.Wilton Ivie: B.S., M.S. in biology from University of Utah....
  
  , 1935 (USA)
• Kibramoa isolata Gertsch, 1958 (Mexico)
• Kibramoa madrona Gertsch, 1958 (USA)
• Kibramoa paiuta Gertsch, 1958 (USA)
• Kibramoa suprenans (Chamberlin, 1919) (USA)
  • Kibramoa suprenans pima Gertsch, 1958 (USA)
• Kibramoa yuma Gertsch, 1958 (USA)

Plectreurys Simon, 1893

• Plectreurys angela Gertsch, 1958 (USA)
• Plectreurys ardea Gertsch, 1958 (Mexico)
• Plectreurys arida Gertsch, 1958 (Mexico)
• Plectreurys bicolor Banks, 1898 (Mexico)
• Plectreurys castanea Simon, 1893 (USA)
• Plectreurys ceralbona Chamberlin, 1924 (Mexico)
• Plectreurys conifera Gertsch, 1958 (USA)
• Plectreurys deserta Gertsch, 1958 (USA)
• Plectreurys globosa Franganillo, 1931 (Cuba)
• Plectreurys hatibonico Alayón, 2003 (Cuba)
• Plectreurys misteca Gertsch, 1958 (Mexico)
• Plectreurys mojavea Gertsch, 1958 (USA)
• Plectreurys monterea Gertsch, 1958 (USA)
• Plectreurys nahuana Gertsch, 1958 (Mexico)
• Plectreurys oasa Gertsch, 1958 (USA)
• Plectreurys paisana Gertsch, 1958 (Mexico)
• †Plectreurys pittfieldi Penney 2009 (Miocene, Dominican Amber)
• Plectreurys schicki Gertsch, 1958 (USA)
• Plectreurys tecate Gertsch, 1958 (Mexico)
• Plectreurys tristis Simon, 1893 (USA, Mexico)
• Plectreurys valens Chamberlin, 1924 (Mexico)
• Plectreurys vaquera Gertsch, 1958 (Mexico)
• Plectreurys zacateca Gertsch, 1958 (Mexico)

Tentatively placed in Plectreuridae:

†Palaeoplectreurys Wunderlich, 2004

• Palaeoplectreurys baltica Wunderlich, 2004 (Late Eocene, Baltic Amber)

External links