Thelyphonida

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Thelyphonida
Mastigoproctus giganteus 224269691.jpg
Mastigoproctus giganteus , Uropygi
Hubbardia pentapeltis female.jpg
Hubbardia pentapeltis , Schizomida
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Clade: Tetrapulmonata
Clade: Thelyphonida
Orders

The clade Thelyphonida consists of two orders of arachnids, Uropygi (whip-scorpions) and Schizomida (short-tailed whip-scorpions). [1] Some sources use the name Thelyphonida to refer only to whip-scorpions rather than the clade. [2] Members of the clade Thelyphonida are mostly small arachnids. The last segment of the abdomen bears a whip-like tail or flagellum, shorter in Schizomida than Uropygi. They use only six legs for walking, the front pair being used for sensing. They are not venomous.

Contents

Biology

Members of the clade Thelyphonida are mostly small, many with a body around 25–30 mm (1.0–1.2 in) long, although some can reach 85 mm (3.3 in). [3] The opisthosoma (abdomen) is a smooth oval of 12 recognizable segments. The first is reduced and forms a pedicel, while the last three are constricted, forming the pygidium. The last segment bears a whip-like tail or flagellum, consisting of 30–40 units in whip-scorpions and no more than four segments in short-tailed whip-scorpions. [4] [5] [6] They share with Amblypygi the use of their first pair of legs for tactile sensing, rather than locomotion. They do not have venom and use their spiny palps to seize prey. Features common to the clade Thelyphonida include fused palpal coxae, pygidial glands, and the first pair of legs having elongated patellae. [2]

Nomenclature

The name Thelyphonida has been used in different senses. In one system, the whip-scorpions are treated as the order Uropygi and the short-tailed whip-scorpions as order Schizomida, within the class Arachnida. This approach is followed by various taxonomic databases as of September 2025. [7] [8] Molecular phylogenetic studies show that the two orders are sister taxa. [9] [1] Thelyphonida is then the clade containing the two, with the related order Amblypygi (whip-spiders) falling outside Thelyphonida, but grouped with it as the clade Pedipalpi. [1]

Clade Pedipalpi

Order Amblypygi (whip-spiders)

Clade Thelyphonida

Order Schizomida (short-tailed whip-scorpions)

Order Uropygi (whip-scorpions)

Confusingly, the names Thelyphonida and Uropygi may be swapped by some sources, with whip-scorpions treated as Thelyphonida, [10] and the parent clade of the two, if used, called Uropygi. [2]

References

  1. 1 2 3 Clouse, Ronald M.; Branstetter, Michael G.; Buenavente, Perry; Crowley, Louise M.; Czekanski-Moir, Jesse; General, David Emmanuel M.; et al. (2017), "First global molecular phylogeny and biogeographical analysis of two arachnid orders (Schizomida and Uropygi) supports a tropical Pangean origin and mid-Cretaceous diversification", Journal of Biogeography , 44 (11): 2660–2672, Bibcode:2017JBiog..44.2660C, doi:10.1111/jbi.13076
  2. 1 2 3 Ruiz, Gustavo R.S. & Valente, Roberta M. (2017), "First description of the male genitalia in a short-tailed whipscorpion (Arachnida: Schizomida), description of the female, and comments on pygidial glands and cuticular ultrastructure of Surazomus algodoal Ruiz & Valente, 2017", PLOS ONE, 18 (8) e0289370, doi: 10.1371/journal.pone.0289370 , PMC   10409265 , PMID   37552704
  3. ↑ Schmidt, Günther (1993), Giftige und gefährliche Spinnentiere[Poisonous and dangerous arachnids] (in German), Westarp Wissenschaften, ISBN   978-3-89432-405-6
  4. ↑ Minelli, Alessandro; Contrafatto, Giancarlo, eds. (2009), Biological Science Fundamentals and Systematics, Encyclopedia of Life Support Systems, vol. III, Oxford, UK: EOLSS Publications, p. 225, ISBN   978-1-84826-990-3 – via Google Books
  5. ↑ Ax, Peter (2000) [1999 original German ed.], Multicellular Animals: The phylogenetic system of the metazoa, vol. II: The Phylogenetic System of the Metazoa, translated by Kiney, S. (English ed.), Springer, p. 103, doi:10.1007/978-3-662-10396-8, ISBN   978-3-642-08681-6, S2CID   28516278 – via Google Books
  6. ↑ Coddington, J.A.; Giribet, G.; Harvey, M.S.; Prendini, L.; Walter, D.E. (2004), "18: Arachnida", in Cracraft, J.; Donoghue, M.J. (eds.), Assembling the Tree of Life, Oxford University Press, pp. 296–318, ISBN   0-19-517234-5
  7. ↑ "Arachnida", Interim Register of Marine and Nonmarine Genera , retrieved 2025-09-02
  8. ↑ "Arachnida", Global Biodiversity Information Facility , retrieved 2025-09-02
  9. ↑ Shultz, Jeffrey W. (2007), "A phylogenetic analysis of the arachnid orders based on morphological characters", Zoological Journal of the Linnean Society, 150 (2): 221–265, doi: 10.1111/j.1096-3642.2007.00284.x
  10. ↑ Garwood, Russell J.; Dunlop, Jason A. (2014), "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders", PeerJ, 2: e641, doi: 10.7717/peerj.641 , PMC   4232842 , PMID   25405073
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