The RTA clade is a clade of araneomorph

spider Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species d ...

s, united by the possession of a

retrolateral tibial apophysis This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids. Links within the glossary are shown . Terms A Abdomen or opisthosoma: One of the two main body parts ...

– a backward-facing projection on the tibia of the male

pedipalp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") a ...

. The clade contains over 21,000 species, almost half the current total of about 46,000 known species of spider. Most of the members of the clade are wanderers and do not build webs. Despite making up approximately half of all modern spider diversity, there are no unambiguous records of the group from the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Creta ...

and

molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleo ...

evidence suggests that the group began to diversify during the

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'', ...

Families

In 2005, Coddington included 39 families in a cladogram showing the RTA clade: *

Agelenidae The Agelenidae are a large family of spiders in the suborder Araneomorphae. Well-known examples include the common "grass spiders" of the genus ''Agelenopsis''. Nearly all Agelenidae are harmless to humans, but the bite of the hobo spider (''Erat ...

Amaurobiidae ''Amaurobiidae'' is a family of three-clawed cribellate or ecribellate spiders found in crevices and hollows or under stones where they build retreats, and are often collected in pitfall traps. Unlidded burrows are sometimes quite obvious in cru ...

Ammoxenidae Ground spiders comprise Gnaphosidae, the seventh largest spider family with over 2,000 described species in over 100 genera distributed worldwide. There are 105 species known to central Europe, and common genera include '' Gnaphosa'', '' Drassode ...

Amphinectidae Desidae is a family of spiders, some of which are known as intertidal spiders. The family is named for the genus '' Desis'', members of which live in a very unusual location — between the tides. The family has been reevaluated in recent years an ...

(

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

; merged into Desidae) *

Anyphaenidae Anyphaenidae is a family of araneomorph spiders, sometimes called anyphaenid sac spiders. They are distinguished from the sac spiders of the family Clubionidae and other spiders by having the abdominal spiracle placed one third to one half of th ...

Cithaeronidae Cithaeronidae is a small family of araneomorph spiders first described by Simon in 1893 Female ''Cithaeron'' are about long, males about . They are pale yellowish, fast-moving spiders that actively hunt at night and rest during the day, buildi ...

Clubionidae The sac spiders of the family Clubionidae have a very confusing taxonomic history. Once, this family was a large catch-all taxon for a disparate collection of spiders, similar only in that they had eight eyes arranged in two rows and conical anter ...

Corinnidae Corinnidae is a family of araneomorph spiders, sometimes called corinnid sac spiders. The family, like other "clubionoid" families, has a confusing taxonomic history. Once it was a part of the large catch-all taxon Clubionidae, now very much sma ...

* Cryptothelidae *

Ctenidae Wandering spiders (''Ctenidae'') are a family of spiders that includes the Brazilian wandering spiders. These spiders have a distinctive longitudinal groove on the top-rear of their oval carapace similar to those of the Amaurobiidae. They are hig ...

Desidae Desidae is a family of spiders, some of which are known as intertidal spiders. The family is named for the genus '' Desis'', members of which live in a very unusual location — between the tides. The family has been reevaluated in recent years an ...

Dictynidae Dictynidae is a family of cribellate, hackled band-producing spiders first described by Octavius Pickard-Cambridge in 1871. Most build irregular webs on or near the ground, creating a tangle of silken fibers among several branches or stems of one ...

* Gallieniellidae *

Gnaphosidae Ground spiders comprise Gnaphosidae, the seventh largest spider family with over 2,000 described species in over 100 genera distributed worldwide. There are 105 species known to central Europe, and common genera include '' Gnaphosa'', '' Drassode ...

Lamponidae Lamponidae is a family of spiders first described by Eugène Simon in 1893. It contains about 200 described species in 23 genera, most of which are endemic to Australia, with the genus ''Centrocalia'' endemic to New Caledonia, and two ''Lampona' ...

* Liocranidae *

Lycosidae Wolf spiders are members of the family Lycosidae (). They are robust and agile hunters with excellent eyesight. They live mostly in solitude, hunt alone, and do not spin webs. Some are opportunistic hunters, pouncing upon prey as they find it or ...

Miturgidae Miturgidae is a family of araneomorph spiders that includes nearly 170 species in 29 genera worldwide. First described by Eugène Simon in 1886, it has been substantially revised, and includes the previous family Zoridae as a synonym, and excludes ...

(paraphyletic) * Oxyopidae *

Philodromidae Philodromidae, also known as philodromid crab spiders and running crab spiders, is a family of araneomorph spiders first described by Tord Tamerlan Teodor Thorell in 1870 (then known as subfamily Philodrominae within Thomisidae). It contains ov ...

* Phyxelididae *

Pisauridae Nursery web spiders (Pisauridae) is a family of araneomorph spiders first described by Eugène Simon in 1890. They resemble wolf spiders (Lycosidae) except for several key differences. Wolf spiders have two very prominent eyes in addition to the ...

Psechridae Psechridae is a family of araneomorph spiders with about 70 species in two genera. These are among the biggest cribellate spiders with body lengths up to and funnel webs more than in diameter. The family belongs to the RTA clade of spiders ...

Salticidae Jumping spiders are a group of spiders that constitute the family Salticidae. As of 2019, this family contained over 600 described genera and over 6,000 described species, making it the largest family of spiders at 13% of all species. Jumping spi ...

* Selenopidae *

Senoculidae ''Senoculus'' is a genus of araneomorph spiders in the family Senoculidae, and was first described by Władysław Taczanowski in 1872. It is the only genus in the family Senoculidae. Species it contains thirty-one species, found in South Americ ...

Sparassidae Huntsman spiders, members of the family Sparassidae (formerly Heteropodidae), are known by this name because of their speed and mode of hunting. They are also called giant crab spiders because of their size and appearance. Larger species sometim ...

Stiphidiidae Stiphidiidae, also called sheetweb spiders, is a family of araneomorph spiders first described in 1917. Most species are medium size (''Stiphidion facetum'' is about long) and speckled brown with long legs. All members of this family occur in ...

Tengellidae Tengellidae is a former family of spiders that has been merged into the family Zoropsidae. Genera formerly placed in Tengellidae now in Zoropsidae include: *'' Anachemmis'' Chamberlin, 1919 *''Austrotengella'' Raven, 2012 *'' Ciniflella'' Mello- ...

(now merged into Zoropsidae) *

Thomisidae The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of thi ...

* Titanoecidae * Trechaleidae *

Trochanteriidae Trochanteriidae is a family of spiders first described by Ferdinand Karsch in 1879 containing about 52 species in6 genera. Most are endemic to Australia though '' Doliomalus'' and '' Trochanteria'' are from South America and ''Plator'' is from As ...

Zodariidae Ant spiders are members of the family Zodariidae. They are small to medium-sized eight-eyed spiders found in all tropical and subtropical regions of South America, Africa, Madagascar, Australia-New Guinea, New Zealand, Arabia and the Indian sub ...

*Zoridae (now a synonym of

) *Zorocratidae (no longer accepted; most genera now placed in

Udubidae Udubidae is a family of araneomorph spiders, most of whose members were formerly placed in the family Zorocratidae, which is no longer accepted. Phylogeny A study investigating the phylogenetic relationships of lycosoid spiders concluded tha ...

) *

Zoropsidae Zoropsidae, also known as false wolf spiders for their physical similarity to wolf spiders, is a family of cribellate araneomorph spiders first described by Philipp Bertkau in 1882. They can be distinguished from wolf spiders by their two rows ...

References

Araneomorphae {{Araneomorphae-stub