Uropygi

Carl Linnaeus first described a whip scorpion in 1758, although he did not distinguish it from what are now regarded as different kinds of arachnid, calling it Phalangium caudatum. Phalangium is now used as a name for a genus of harvestmen (Opiliones). In 1802, Pierre André Latreille was the first to use a genus name solely for whip scorpions, namely Thelyphonus. from (') "tail" and (') "rump" referring to the whip-like flagellum on the end of the pygidium, a small plate made up of the last three segments of the abdominal exoskeleton. The classification and scientific name used for whip scorpions varies. Originally, Amblypygi (whip spiders), Uropygi and Schizomida (short-tailed whipscorpions) formed a single order of arachnids, Pedipalpi. Pedipalpi was later divided into two orders, Amblypygi and Uropygi (or Uropygida). Schizomida was then split off from Uropygi into a separate order. or Thelyphonida s.l. Conversely, when the name Thelyphonida is used for the whip scorpions alone, the parent clade may be called Uropygi, or Uropygi sensu lato. The table below summarizes the two usages. When the qualifications s.l. and s.s. are omitted, the names Uropygi and Thelyphonida are ambiguous. Phylogenetic studies show the three groups, Amblypygi, Uropygi s.s. and Schizomida, to be closely related. The Uropygi s.s. and Schizomida likely diverged in the late Carboniferous, somewhere in the tropics of Pangaea. ==Description==

Whip scorpions range from in length, with most species having a body no longer than ; the largest species, of the genus Mastigoproctus, can reach . An extinct Mesoproctus from the Lower Cretaceous Crato Formation could be the same size. Because of their legs, claws, and "whip", though, they can appear much larger, and the heaviest specimen weighed was 12.4 grams (0.44 oz). The opisthosoma consists of 12 segments. The first segment forms a pedicel, and each of the next eight segments has dorsal tergites. The last three segments are fused into closed rings, forming a pygidium that ends with a flagellum of 30–40 units. Like the related orders Schizomida and Amblypygi, whip scorpions use only six legs for walking, with the first two legs serving as antennae-like sensory organs. All species also have very large scorpion-like pedipalps (pincers) but there is an additional large spine on each palpal tibia. They have one pair of median eyes at the front of the cephalothorax and up till five pairs of lateral eyes on each side of the head, a pattern also found in scorpions. Whip scorpions have no venom glands, but they have glands near the rear of their abdomen that can spray a combination of acetic acid and caprylic acid when they are bothered. The acetic acid gives this spray a vinegar-like smell, giving rise to the common name vinegaroon. ==Behaviour==

'', a predator of millipedes Whip scorpions are carnivorous, nocturnal hunters feeding mostly on insects, millipedes, scorpions, and terrestrial isopods, The white young that hatch from the postembryos climb onto their mother's back and attach themselves there with special suckers. After the first moult, when they look like miniature adults but with bright red palps, they leave the burrow. The mother may live up to two more years. The young grow slowly, going through four moults in about four years before reaching adulthood. They live for up to another four years. ==Distribution and habitat==

Whip scorpions are found in tropical and subtropical areas, excluding Europe and Australia. Also, only a single species is known from Africa: Etienneus africanus, probably a Gondwana relict, endemic to Senegal, the Gambia and Guinea-Bissau. They usually dig burrows with their pedipalps, to which they transport their prey. ==Subtaxa==

As of 2026, the World Uropygi Catalog accepted the following 18 extant genera, all placed in the family Thelyphonidae: • Etienneus Heurtault, 1984 • Ginosigma Speijer, 1936 • Glyptogluteus Rowland, 1973 • Hypoctonus Thorell, 1888 • Labochirus Pocock, 1894 • Mastigoproctus Pocock, 1894 • Mayacentrum Viquez & Armas, 2006 • Mimoscorpius Pocock, 1894 • Ravilops Víquez & Armas, 2005 • Sheylayongium Teruel, 2018 • Thelyphonellus Pocock, 1894 • Thelyphonoides Krehenwinkel, Curio, Tacud & Haupt, 2009 • Thelyphonus Latreille, 1802 • Typopeltis Pocock, 1894 • Uroproctus Pocock, 1894 • Valeriophonus Viquez & Armas, 2005 • Wounaan Botero-Trujillo, Moreno-González & Prendini, 2024 • Yekuana Botero-Trujillo, Moreno-González & Prendini, 2024 In addition, nine extinct genera were accepted, two within the family Thelyphonidae: • †Mesoproctus Dunlop, 1998 • †Mesothelyphonus Cai & Huang, 2017 and seven unplaced as to family: • †Burmathelyphonia Wunderlich, 2015 • †Geralinura Scudder, 1884 • †Inmontibusichnus Knecht, Benner, Dunlop & Renczkowski, 2023 • †Parageralinura Tetlie & Dunlop, 2008 • †Parilisthelyphonus Knecht, Benner, Dunlop & Renczkowski, 2023 • †Proschizomus Dunlop & Horrocks, 1996 • †Prothelyphonus Frič, 1904 ==Notes==