Palpigradi


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Palpigradi

 

an order of very small (to 2 mm) soil-dwelling arachnids. The body is elongated, and the cephalothorax is covered above by three plates. The abdomen has 11 segments and a long tail. The chelicerae are clawed. The pedipalps are fitted for walking, and the front pair of legs serve a tactile function. The arachnids are marked by cutaneous respiration, and most species lack tracheae. The lower surface of the abdomen has vesicles that draw in moisture. The excretory organs are coxal glands.

There are about 25 species, distributed primarily in the Mediterranean region, the Americas (from California to Chile), southeastern Asia, and southern Australia. No species have been encountered in the USSR. The most common species are those of the genus Koenenia. Palpigradi dwell in warm regions with karstic terrain. They live under rocks and descend deep into cracks in the limestone, often falling into caves.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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References in periodicals archive ?
Catalogue of the Smaller Arachnid Orders of the World: Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei and Solifugae.
Crustacea dominate as predators (Cheng 1976), while a range of centipedes (Class Chilopoda), symphylids (Class Symphyla), pauropods (Class Pauropoda), millipedes (Class Diplopoda), scorpions (Order Scorpiones), microwhip scorpions (Order Palpigradi), pseudoscorpions (Order Pseudoscorpiones), mites and ticks (Order Acari) and spiders (Order Araneae) have also been recorded as living in the intertidal region worldwide (Roth & Brown 1976).
Entre los 129 capitulos que versan sobre la sistematica de Arthropoda, tres se refieren a taxones afines al grupo de artropodos: "Pentastomida", "Onychophora" y "Tardigrada"; en tanto que 126 resenan los taxones caracteristicos de Arthropoda, asi los grupos de Chelicerata se incluyen en 14 capitulos relativos a "Xiphosura", "Pycnogonida", "Palpigradi", "Schizomida", "Uropygi", "Amblypygi", "Solifugae", "Ricinulei", "Araneae" "Scorpiones", "Pseudoscorpionida", "Opiliones", "Acari" y "Oribatei (Acari)"; y en cuatro capitulos de Myriapoda se discuten "Symphyla", "Pauropoda", "Geophilomorpha" y "Diplopoda".
Palpigradi.--A single, ?Pliocene, fossil palpigrade has been described from the Onyx Marble of Arizona, USA (Rowland & Sissom 1980).
Exceptions are, besides Opiliones (see below), Pseudoscorpiones (Weygoldt 1969), and anactinotrichid mites (Anactinotrichida = Parasitiformes s.l.) (Alberti 2006; Dunlop & Alberti 2007), which have no median eyes, and the eyeless Palpigradi. The extant Ricinulei are usually considered to lack eyes although they bear more or less distinct light spots on the cuticle that may be associated with light reception.
Three arachnid orders, Amblypygi, Uropygi, and Palpigradi share a narrow pedicel with Araneae, but the pro/ opisthosoma connection in spiders is especially flexible, probably to promote mobility of the spinnerets.
Two species of Palpigradi have been previously reported from Morocco (Harvey 2003).
AF005445 Uropygi Mastigoproctus giganteus AF005446 (Lucas 1835) Schizomida Stenochrus portoricensis AF005444 Chamberlin 1922 Ricinulei Pseudocellus pearsei U91489 (Chamberlin & Ivie 1938) Palpigradi Eukoenenia sp.