Phylogeny and Classification of Spiders
18 FROM: Ubick, D., P. Paquin, P.E. Cushing, andV. Roth (eds). 2005. Spiders of North America: an identification manual. American Arachnological Society. 377 pages. Chapter 2 PHYLOGENY AND CLASSIFICATION OF SPIDERS Jonathan A. Coddington ARACHNIDA eyes, jumping spiders also share many other anatomical, Spiders are one of the eleven orders of the class Arach- behavioral, ecological, and physiological features. Most nida, which also includes groups such as harvestmen (Opil- important for the field arachnologist they all jump, a useful iones), ticks and mites (Acari), scorpions (Scorpiones), false bit of knowledge if you are trying to catch one. Taxonomic scorpions (Pseudoscorpiones), windscorpions (Solifugae), prediction works in reverse as well: that spider bouncing and vinegaroons (Uropygi). All arachnid orders occur in about erratically in the bushes is almost surely a salticid. North America. Arachnida today comprises approximately Another reason that scientists choose to base classifica- 640 families, 9000 genera, and 93,000 described species, but tion on phylogeny is that evolutionary history (like all his- the current estimate is that untold hundreds of thousands tory) is unique: strictly speaking, it only happened once. of new mites, substantially fewer spiders, and several thou- That means there is only one true reconstruction of evolu- sand species in the remaining orders, are still undescribed tionary history and one true phylogeny: the existing clas- (Adis & Harvey 2000, reviewed in Coddington & Colwell sification is either correct, or it is not. In practice it can be 2001, Coddington et ol. 2004). Acari (ticks and mites) are complicated to reconstruct the true phylogeny of spiders by far the most diverse, Araneae (spiders) second, and the and to know whether any given reconstruction (or classifi- remaining taxa orders of magnitude less diverse.
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