Palpigradi


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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.

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Group Paleozoic Mesozoic Cenozoic Total Pycnogonida 6 3 -- 9 "Euchelicerata" 5 -- -- 5 Xiphosura 75 20 1 96 Chasmataspidida 8 -- -- 8 Eurypterida 241 -- -- 241 Scorpiones 79 16 16 111 Opiliones 7 1 17 25 Phalangiotarbida 30 -- -- 30 Pseudoscorpiones 1 2 35 38 Solifugae 2 1 2 5 Acari: Anactinotrichida -- 1 10 11 Acari: Actinotrichida 15 15 253 283 Palpigradi -- -- 1 1 Ricinulei 15 -- -- 15 "Pantetrapulmonata" 3 -- -- 3 Trigonotarbida 71 -- -- 71 Araneae 18 31 930 979 Haptopoda 1 -- -- 1 Amblypygi 5 1 3 9 Uropygi 6 1 -- 7 Schizomida -- -- 4 4 all Chelicerata 588 92 1272 1952 Arachnida only 253 69 1271 1593 Table 2.
Alberti 2006; Dunlop & Alberti 2007), which have no median eyes, and the eyeless Palpigradi.
Catalogue of the Smaller Arachnid Orders of the World: Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei and Solifugae.
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).
Eukoenenia includes 60 species and is the most diverse genus of Palpigradi (Harvey 2002, 2003; Mayoral & Barranco 2002a).
AF005445 Uropygi Mastigoproctus giganteus AF005446 (Lucas 1835) Schizomida Stenochrus portoricensis AF005444 Chamberlin 1922 Ricinulei Pseudocellus pearsei U91489 (Chamberlin & Ivie 1938) Palpigradi Eukoenenia sp.
Some of the smaller arachnid groups, such as the 78 species of Palpigradi and 55 Ricinulei species, are so poorly known that no conclusions can be made about their social tendencies.
Arachnida, Mygalomorphae, Araneomorphae in Part, Pseudoscorpionida, Amblypygida, Palpigradi (D.
Los aracnidos de Mexico parte 1: Ricinulei, Amblypygi, Solifugae, Palpigradi, Schizomida, Uropygi.
Within arachnids only the spermatozoa of Scorpiones, Uropygi, Amblypygi, Araneae, Pseudoscorpiones and Ricinulei possess a flagellum (summary in Alberti 2000), in contrast to the spermatozoa of Solifugae, Acari, Palpigradi and Opiliones, which are aflagellate (the only exception is the opilionid genus Siro which shows an axoneme during the spermatogenesis; Juberthie et al.