Scheme of classification - Chamberlin (1931)
Very few phylogenetic hypotheses have been proposed in the scientific literature. Chamberlin (1931) depicted a “scheme of classification” which was modeled on the classification that he proposed in the monograph. Some rearrangements were proposed by later authors, including the addition and deletion of families, but the overall scheme remained essentially the same.
- The scheme of classification proposed by Chamberlin 1931
Phylogenetic hypothesis - Harvey (1992)
Harvey (1992) presented a phylogenetic hypothesis based upon a cladistic analysis of 126 characters. This tree (reproduced below) proposed a number of significant changes:
- The Feaelloidea was thought to represent the sister-group to the Chthonioidea, which were united in the suborder Epiocheirata (meaning gentle hand, and referring to the lack of a venom apparatus in the chelal fingers).
- The remaining pseudoscorpions were placed in the suborder Iocheirata (meaning “poison hand” and referring to the presence of a venom apparatus in the chelal fingers).
- Within the Iocheirata, the Neobisioidea were hypothesized as the sister-group to the remaining taxa. This is in contrast to the classifications in which all pseudoscorpions with separate metatarsi and tarsi in each leg were placed in the Diplosphyronida (e.g. Chamberlin, 1930, 1931) or Neobisiinea (Beier, 1932).
- Recognition of the superfamily Olpioidea for Olpiidae and Menthidae. These families were previously treated within the Garypoidea by previous authors.
- Transfer of the Cheiridiidae and Pseudochiridiidae (part of the Cheiridioidea) to within the Garypoidea.
- Recognition of the superfamily Sternophoridea for Sternophoridae. This enigmatic family was previously regarded as a member of the Cheiridioidea by Chamberlin (1931) and all subsequent authors, despite Chamberlin’s misgivings regarding this relationship.
- Harvey's proposed phylogeny of the pseudoscorpion order (1992)
To fully clarify the current state of pseudoscorpion phylogeny and classification, the following alterations have been proposed since the publication of Harvey (1992):
- Judson (2000) disputed the synonymy of the Cheiridioidea with the Garypoidea, and revalidated the Cheiridioidea for Cheiridiidae and Pseudochiridiidae.
- Judson (2004) proposed that the Garypinidae — previously a subfamily of the Olpiidae — be recognized as a distinct family.
- Judson (1992, 1993) removed Pseudotyrannochthoniinae from Chthoniidae and treated it as a separate family of Chthonioide.
- Murienne et al. (2008) presented the first molecular phylogenetic analysis that mostly corroborated the previous trees and alterations. However, several anomalies were detected.