Withiid  Pseudoscorpions  -  Family:  Withiidae
      The smallest of the four families in the Superfamily: Cheliferoidea, the Withiidae were originally considered to be subfamily within the Cheliferidae by Chamberlin in 1931; however, the German arachnologist, Peter J.H. Weygoldt (1933-2021) elevated them to the rank of family in 1970.  The World Catalogue of Pseudoscorpions now counts 174 extant species in 38 genera (plus one species in one genus extinct).   The extant species are divided among two subfamilies.
The oldest fossils discovered so far are from the extinct Genus: Beierowithius.   Found in Baltic amber in Poland they are dated at 39 - 33.9 My old.  More recent fossils have been found in the Dominican Republic (from the Miocene, 20.4 - 13.8 My ago).   Fossils have also been found in Tanzania but these remain somewhat contentious.
      The family is said to have a cosmopolitan distribution but most species - which usually hide and live in leaf litter, under bark and rocks -  are quite localised.  There is however, one species that bucks that trend; the species Withius piger has been identified from far flung placed such as Scandinavia, New Zealand and Mexico as well as North Africa  where the specimens originally described in 1878 by Eugene Simon were found.   Withius piger lives  'primarily in stored grain' which is likely to be an opportunistic adaptation to human activity and this also explains its wide distribution, having been introduced, as it is in Australia, in most areas where it lives.   It is listed here as a possible resident of the Northern Rivers region but it should be mentioned that Australian records of the species are quite rare and so far no local records exist.

Subfamily:  Withiinae
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      Withius piger     (possible occurrence)

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Taxonomy:
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Phylum:   Arthropoda   (Arthropods)
          > Subphylum:   Chelicerata   (Chelicerates)
                    > Class:   Arachnida   (Arachnids)  
                                        > Order:   Pseudoscorpiones   (Pseudoscorpions)
                                                  > Suborder:   Iocheirata
                                                            > Infraorder:   Panctenata
                                                                 > Zoosection:   Elassommatina
                                                                      > Superfamily:   Cheliferoidea
                                                                                > Family:   Withiidae   (Withiid Pseudoscorpions)
                                                                                          >  Subfamily:   Withiinae
                                                                                                              > Genus:   Withius
                                                                                                                        > Species:   W. piger^

^  =  possibly
References  and  links:
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>      Simon, E., (1878).   ‘Études arachnologiques. XI.  Liste des espèces de la famille des Cheliferidae qui habitant l'Algérie et le Maroc.’    Annales de la Société Entomologique de France,  5 (8): 144-153.

      https://bie.ala.org.au/species/https://biodiversity.org.au/afd/taxa/46bde684-065c-49b0-bc24-47f5c220dfcf#overview​
      https://museum.wa.gov.au/catalogues/pseudoscorpions/family/withiidae
​      https://species.wikimedia.org/wiki/Peter_Weygoldt
      https://www.biodiversity.org.au/afd/taxa/WITHIIDAE​
      https://www.mindat.org/taxon-7257.html

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