The RTA clade is a clade of araneomorphspiders, united by the possession of a retrolateral tibial apophysis – a backward-facing projection on the tibia of the male pedipalp.[1] The clade contains over 21,000 species, almost half the current total of about 46,000 known species of spider.[2] Most of the members of the clade are wanderers and do not build webs.[3] Despite making up approximately half of all modern spider diversity, there are no unambiguous records of the group from the Mesozoic and molecular clock evidence suggests that the group began to diversify during the Late Cretaceous.[4]
Families
In 2005, Coddington included 39 families in a cladogram showing the RTA clade:[5]
^Coddington, Jonathan A. & Levi, Herbert W. (1991), "Systematics and evolution of spiders (Araneae)", Annual Review of Ecology and Systematics, 22: 565–592, doi:10.1146/annurev.es.22.110191.003025, JSTOR2097274
^Hormiga, Gustavo & Griswold, Charles E. (2014), "Systematics, Phylogeny, and Evolution of Orb-Weaving Spiders", Annual Review of Entomology, 59 (1): 487–512, doi:10.1146/annurev-ento-011613-162046, PMID24160416
^Coddington, Jonathan A. (2005), "Phylogeny and classification of spiders"(PDF), in Ubick, D.; Paquin, P.; Cushing, P.E. & Roth, V. (eds.), Spiders of North America: an identification manual, American Arachnological Society, pp. 18–24, retrieved 2015-09-24
