Belongs within: Euchelicerata.
Contains: Chthoniidae, Iocheirata.
The Pseudoscorpiones are a group of small arachnids, superficially resembling scorpions due to the possession of large chelate pedipalps but lacking the elongate metasoma or posterior sting of a scorpion. Basal representatives of the Pseudoscorpiones include the Feaelloidea, characterised by anterior projections on the carapace, and fusion of the eleventh tergite and sternite to surround the anus.
Characters (Muchmore 1990): Body divided between anterior prosoma (cephalothorax) and posterior opisthosoma (abdomen), with the two sections broadly connected. Dorsal surface of prosoma covered by single large carapace; one or two pairs of eyes often present laterally toward the front. Venter of prosoma covered by coxae of palps and legs. Chelicerae two-segmented, chelate, attached close together under anterior margin of carapace; several setae present on chelicera with cluster of setae on medial side forming flagellum; comblike or membranous serrula present along side of each finger; spinneret (galea) present near end of movable finger. Pedipalps six-segmented, chelate; trichobothria present on chela. Legs six- or seven-segmented; pretarsus bearing two claws and arolium. Opisthosoma with twelve tergites; usually only eleven visible sternites; eleventh tergite and sternite sometimes fused as circumanal ring; twelfth tergite and sternite each very small anal plate. Spiracles present at lateral edges of third and fourth sternites.
<==Pseudoscorpiones [Cheliferinea, Chelonethi, Epiocheirata, Homosphyronida, Monosphyronida]
|--+--ChthoniidaeMHG08
| `--IocheirataMHG08
`--FeaelloideaMHG08
|--Feaella [Feaellidae]MHG08
| |--F. (Tetrafeaella) affinis Hirst 1911J97
| `--F. anderseniMHG08
`--PseudogarypidaeMHG08
|--Neopseudogarypus Morris 1948H81
| `--*N. scutellatus Morris 1948H81
`--PseudogarypusMHG08
|--P. banksiM90
|--P. bicornisMHG08
|--P. extensus Beier 1937S93
|--P. hemprichii Beier 1937S93
`--P. minor Beier 1947S93
Pseudoscorpiones incertae sedis:
‘Acarus’ scorpioides Linnaeus 1758H02
Opsochernes carbophilusFF99
Thelassochernes pallipesFF99
EctocerasT89
|--E. bidensT89
`--E. helferiT89
MegathisT89
|--M. desiderataT89
`--M. kochiiT89
Obisium Leach 1817S06
|--O. longimanumR13
`--O. trifidumT89
Dracochela Schawaller, Shear & Bonamo 1991 [Dracochelidae]H02
`--D. deprehendor Schawaller, Shear & Bonamo 1991H02
*Type species of generic name indicated
References
[FF99] Forster, R., & L. Forster. 1999. Spiders of New Zealand and their World-wide Kin. University of Otago Press: Dunedin (New Zealand).
[H81] Harvey, M. S. 1981. A checklist of the Australian Pseudoscorpionida. Bulletin of the British Arachnological Society 5 (6): 237–252.
[H02] Harvey, M. S. 2002. The neglected cousins: what do we know about the smaller arachnid orders? Journal of Arachnology 30 (2): 357–372.
[J97] Judson, M. L. I. 1997. Catalogue of the pseudoscorpion types (Arachnida: Chelonethi) in the Natural History Museum, London. Occasional Papers on Systematic Entomology 11: 1–54.
[M90] Muchmore, W. B. 1990. Pseudoscorpionida. In: Dindal, D. L. (ed.) Soil Biology Guide pp. 503–527. John Wiley & Sones: New York.
[MHG08] Murienne, J., M. S. Harvey & G. Giribet. 2008. First molecular phylogeny of the major clades of Pseudoscorpiones (Arthropoda: Chelicerata). Molecular Phylogenetics and Evolution 49: 170–184.
[R13] Reuter, O. M. 1913. Lebensgewohnheiten und Instinkte der Insekten bis zum Erwachen der sozialen Instinkte. R. Friedländer & Sohn: Berlin.
[S93] Selden, P. A. 1993. Arthropoda (Aglaspidida, Pycnogonida and Chelicerata). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 297–320. Chapman & Hall: London.
[S06] Strand, E. 1906. Die arktischen Araneae, Opiliones und Chernetes. In: Römer, F., & F. Schaudinn (eds) Fauna Arctica. Eine Zusammenstellun der arktischen Tierformen, mit besonder Berücksichtigung des Spitzbergen-Gebietes auf Grund der Ergebnisse der Deutschen Expedition in das Nördliche Eismeer im Jahre 1898 vol. 4 pp. 431–478. Gustav Fischer: Jena.
[T89] Thorell, T. 1889. Viaggio di Leonardo Fea in Birmania e regioni vicine. XXI.—Aracnidi Artrogastri Birmani raccolti da L. Fea nel 1885–1887. Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 521–729.