Tube-dwelling spider
Encyclopedia
The tube-dwelling spiders (family Segestriidae) consist of two large and widespread genera (Segestria and Ariadna) and one monotypic
genus
(Gippsicola from Australia
). The family is easily recognized because its members have six eyes (most spiders have eight) arranged in a semicircle and have the first three pairs of legs arranged forward (most spider
s have only the first two pairs so arranged.) The leg structure appears to be an adaptation for living in silken tubes, which unlike those of the atypical tarantula
s, may branch and are often built in tree
bark fissures, as well as under stones. These are haplogyne primitive araneomorphs related to the Dysderidae
. Both Segestria and Ariadna are known from North America
, South America
, Eurasia
, Africa
and New Zealand
, while Ariadna is also known from Australia. This wide distribution attests to the ancient origin of this family.
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus
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...
(Gippsicola from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
). The family is easily recognized because its members have six eyes (most spiders have eight) arranged in a semicircle and have the first three pairs of legs arranged forward (most spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s have only the first two pairs so arranged.) The leg structure appears to be an adaptation for living in silken tubes, which unlike those of the atypical tarantula
Atypical tarantula
The atypical tarantulas or purseweb spiders consist of only three genera. Purseweb spiders are accomplished ambush predators that spend most of their time in a sock-like, silken retreat on the ground from where they kill their prey....
s, may branch and are often built in tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
bark fissures, as well as under stones. These are haplogyne primitive araneomorphs related to the Dysderidae
Dysderidae
The family Dysderidae are araneomorph spiders found primarily in Eurasia, although extending into North Africa, with very few species occurring in South America, and one introduced into many regions of the world.Dysderids have six eyes, and are haplogyne, i.e...
. Both Segestria and Ariadna are known from 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...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, while Ariadna is also known from Australia. This wide distribution attests to the ancient origin of this family.
Genera
- Ariadna Audouin, 1826 (84 species; America, Africa, Asia, Australia)
- Gippsicola Hogg, 1900 (1 species; Australia)
- Segestria Latreille, 1804 (20 species; Palearctic, Americas, New Zealand, Central Asia)
See also
- Spider families
- List of Segestriidae species