(Partly) after Wheeler & Hayashi, 1998, Shultz, 2007, and Dunlop, 2010

<==o Arachnida (hämähäkkieläimet; arachnids, spider-like arthropods)
   |--o Dromopoda sensu Schulz, 1990
   |  |-- Opiliones Sundevall, 1833 (harvestmen; lukit)
   |  `--o Novogenuata
   |     |-- Scorpionida Latreille, 1817 (scorpions; skorpionit)
   |     `--o Haplocnemata Börner, 1904
   |        |-- Pseudoscorpionida [Pseudoscorpiones; Chelonethida] (false scorpions; valeskorpionit)
   |        `-- Solifugae 1833 [Solpugida Banks, 1900; Solpugides Gervais, 1844; Solpugae Koch, 1842] (sunspiders, camelspiders, windscorpions; arolukit)
   `--+--o Acaromorpha Dubinin, 1957
      |  |-- Acari Leach, 1817 (ticks & mites; punkit)
      |  `--+?- †Trigonotarbida Petrunkevitch, 1949 sensu Dunlop, 1996 [Anthracomarti Karsh, 1882; Meridogastra Thorell & Lindström, 1885; Eurymarti matthew, 1895; Trigonotarbi Petrunkevitch, 1949]
      |     `-- Ricinulei Thorell, 1876 (hooded tickspiders; huppuhämähäkit)
      `--+?- †Phalangiotarbida (Haase, 1890) Petrunkevitch, 1955
         `--o Megoperculata Shultz, 1990
            |-- Palpigradi Thorell, 1900 (blind scorpions; micro whip-scorpions; sokkoskorpionit)
            `--o PanTetrapulmonata Shultz, 2007
               |?- †Trigonotarbida Petrunkevitch, 1949 sensu Schulz, 2007 [Anthracomarti Karsh, 1882; Meridogastra Thorell & Lindström, 1885; Eurymarti Matthew, 1895; Trigonotarbi Petrunkevitch, 1949]
               `--+?-o †Uraraneida Selden & Shear, 2008
                  |  |-- †Attercopus fimbriunguis (Shear, Selden & Rolfe, 1987) Selden & Shear in Selden, Shear & Bonamo, 1991 [Gelasinotarbus? fimbriunguis Shear, Selden & Rolfe, 1987]
                  |  `-- †Permarachne novokshonovi Eskov & Selden, 2005
                  `--o Tetrapulmonata Shultz, 1990
                     |--+-- †Idmonarachne brasieri Garwood, Dunlop, Selden, Spencer, Atwood, Vo & Drakopoulos, 2016
                     |  `-- Araneae Clerck, 1757 (spiders; hämähäkit )
                     `--o Schizotarsata Shultz, 2007
                        |?- †Plesiosiro madeleyi Pocock, 1911; L.Carb. WEu. [Haptopoda Pocock, 1911: Plesiosironidae Pocock, 1911]
                        `--o Pedipalpi Börner, 1904
                           |-- Amblypygi (whip-spiders; skorpionilukit)
                           `--o Uropygi Thorell, 1882 sensu Shultz, 2007
                              |--o Thelyphonida Latreille, 1804 [Uropygi] (whip scorpions; vinagroons; siimaskorpionit)
                              |  |-- Geralinuridae
                              |  |-- Hypoctonidae [Thelyphonidae: Hypoctoninae]
                              |  `--o Thelyphonidae Lucas, 1835
                              |     |-- Mastigoproctinae
                              |     |-- Thelyphoninae
                              |     `-- Typopeltinae
                              `-- Schizomida Petrunkevitch, 1945 (short-tailed whip-scorpions)


Alternative phylogenies of Arachnides:

After Garwood, Dunlop, Selden, Spencer, Atwood, Vo & Drakopoulos, 2016 (fig. 3a)

<==o Arachnida
   |-- Palpigradi
   `--+--+--+-- Opiliones
      |  |  `-- †Phalangiotarbida
      |  `--+-- Pseudoscorpiones
      |     `-- Scorpiones
      `--+--+-- Ricinulei
         |  `--+-- Parasitiformes
         |     `--+-- Solifugae
         |        `-- Acariformes
         `--+-- †Trigonotarbida
            |--+-- †Uraraneida
            |  `--+-- †Idmonarachne
            |     `-- Araneae
            `--+-- †Plesiosiro
               `--+-- Amblypygi
                  `--+-- Thelyphonida
                     `-- Schizomida

Reference(s):

  • Garwood, R. J., Dunlop, J. A., Selden, P. A., Spencer, A. R. T., Atwood, R. C., Vo, N. T. & Drakopoulos, M., 2016: Almost a spider: a 305-million-year-old fossil arachnid and spider origins.
    –Proceedings of the Royal Society of London B: Biological Sciences: Vol. 283, #1827, pp. [doi: 10.1098/rspb.2016.0125]

After Shultz, 2007

<==o Arachnida
   |--o Stomothecata
   |  |-- Opiliones
   |  `-- Scorpionida
   `--+-- Palpigradi
      |--o Acaromorpha
      |  |-- Acariformes
      |  `--o Cryptognomae
      |     |-- Ricinulei
      |     `-- Anactinotrichida
      `--+--o Haplocnemata
         |  |-- Pseudoscorpionida
         |  `-- Solifugae
         `--o PanTetrapulmonata
            |-- †Trigonotarbida
            `--o Tetrapulmonata
               |-- Araneae
               `--o Schizotarsata
                  |-- †Plesiosiro
                  `--o Pedipalpi
                     |-- Amblypygi
                     `--o Uropygi
                        |-- Thelyphonida
                        `-- Schizomida

Reference(s):

  • Shultz, J. W., 2007: A phylogenetic analysis of the arachnid orders based on morphological characters.
    –Zoological Journal of the Linnean Society: Vol. 150, #2, pp. 221-265 [doi: 10.1111/j.1096-3642.2007.00284.x]

After Giribet et al., 2002 (via Shultz, 2007)

<==o Arachnida
   |--o Dromopoda
   |  |-- Opiliones
   |  `--o Novogenuata
   |     |-- Scorpionida
   |     `--o Haplocnemata [“Apatellata”]
   |        |-- Pseudoscorpionida
   |        `-- Solifugae
   `--o Micrura
      |-- Acari
      `--+-- Palpigradi
         `--+-- Ricinulei
            `--o Tetrapulmonata
               |-- Araneae
               `--o Pedipalpi
                  |-- Amblypygi
                  `--o Uropygi
                     |-- Thelyphonida
                     `-- Schizomida

After Wheeler & Hayashi, 1998 (via Shultz, 2007)

<==o Arachnida
   |--o Dromopoda
   |  |-- Opiliones
   |  `--o Novogenuata
   |     |-- Scorpionida
   |     `--o Haplocnemata [“Apatellata”]
   |        |-- Pseudoscorpionida
   |        `-- Solifugae
   `--o Micrura
      |--o Acaromorpha
      |  |-- Ricinulei
      |  `-- Acari
      `--o Megoperculata
         |-- Palpigradi
         `--o Tetrapulmonata
            |--o Uropygi
            |  |-- Thelyphonida
            |  `-- Schizomida
            `--o Labellata
               |-- Amblypygi
               `-- Araneae

Reference(s):

  • Wheeler, W. C. & Hayashi, C. Y., 1998: The phylogeny of the extant chelicerate orders.
    –Cladistics: Vol 14, #2, pp. 173-192

After Shultz, 1990 (via Shultz, 2007)

<==o Arachnida
   |--o Dromopoda
   |  |-- Opiliones
   |  `--o Novogenuata
   |     |-- Scorpionida
   |     `--o Haplocnemata [“Apatellata”]
   |        |-- Pseudoscorpionida
   |        `-- Solifugae
   `--o Micrura
      |--o Acaromorpha
      |  |-- Ricinulei
      |  `-- Acari
      `--o Megoperculata
         |-- Palpigradi
         `--o Tetrapulmonata
            |-- Araneae
            `--o Pedipalpi
               |-- Amblypygi
               `--o Uropygi
                  |-- Thelyphonida
                  `-- Schizomida

After Van der Hammen, 1989 (via Shultz, 2007)

<==o Arachnida
   |--o Myliosomata
   |  |-- Opiliones
   |  `--+-- Xiphosura
   |     `-- Scorpionida
   `--o Rostrosomata
      |--o Sternocoxata
      |  |--o Haplocnemata [“Apatellata”]
      |  |  |-- Pseudoscorpionida
      |  |  `-- Solifugae
      |  `--o Epimerata
      |     |-- Palpigradi
      |     `-- Acariformes [Acari]
      `--o Neosternata
         |--o Cryptognomae
         |  |-- Ricinulei
         |  `-- Anactinotrichida [Acari]
         `--o Tetrapulmonata [“Arachnida”]
            |--o Uropygi
            |  |-- Thelyphonida
            |  `-- Schizomida
            `--+-- Amblypygi
               `-- Araneae

After Weygoldt & Paulus, 1979 (via Shultz, 2007)

<==o Arachnida
   |-- Scorpionida
   `--o Lipoctena
      |--o Apulmonata
      |  |-- Palpigradi
      |  `--o Holotracheata
      |     |--o Haplocnemata
      |     |  |-- Pseudoscorpionida
      |     |  `-- Solifugae
      |     `--o Cryptoperculata
      |        |-- Opiliones
      |        `--o Acaromorpha [“Acarinomorpha”]
      |           |-- Ricinulei
      |           `-- Acari
      `--o Tetrapulmonata [“Megoperculata”]
         |--o Uropygi
         |  |-- Thelyphonida
         |  `-- Schizomida
         `--o Labellata
            |-- Amblypygi
            `-- Araneae

Reference(s):