Mouse  Spiders  -  Family:  Actinopodidae
      Restricted to just Australia and South America the Mouse Spiders are medium to large spiders with a well-rounded egg-shaped abdomen and a large  shiny cephalothorax with a bulbous head and chelicerae.  Their eyes are well spaced out across the head rather than clustered together.  The predominant colours are black or very dark brown but the chelicerae, abdomen and lower halves of the legs often display bright colours. Bodylength varies from 10 - 35 mm depending on species and females tend to be larger than the males.  The females are often plain black, robustly built and have relatively large bodies for their short, thick legs. Male Mouse Spiders are a bit more slender with longer legs and they are the one displaying the species specific colouring.   Recent work by a number of arachnologists have seen the family be expanded by 75 species over the past five years to now  contain 124 species in 3 genera as of December 2023 although, due to their elusive nature it is entirely possible that there are still more species left to be discovered than there are known right now.
      There are currently no fossils known of Actinopodid spiders but their present distribution suggests that their ancestors do predate the break-up of Gondwana some 180 Mya confirming their ancient origins.
Mouse Spiders are ambush hunters who build tunnels usually with hinged lids*.   They will position themselves at the entrance of the tunnel with the lid closed and when they sense the prey nearby they will rush from the tunnel entrance to grab it. For many species the lid is all but indistinguishable from its' surroundings.  The tunnel, often lined with silk,  can be as long as 30 cm and is not just a straight tube, it often has at least one side chamber connected to it and sometimes, more than one way to reach the surface.  The female spiders spends her entire life in it - although she may occassionally forage outside for a short duration -  the male stays until he reaches sexual maturity at which stage he will periodically leave or even abandon his tunnel in search of a mating partner.  The female will deposit her eggs and often care for her young inside the tunnel until the spiderlings are old enough to leave the nest.
*  =  The term 'trapdoor' is a misnomer as it suggests an inward falling device used to 'trap' the prey.  Instead the lid always opens outwards, allowing the spider to
​emerge from the tunnel and grab the prey  with its' legs.  From a spiders' viewpoint, a trapdoor could not work.
       Of the Australian contingent of Actinopodid spiders, the Red-headed Mouse Spider is the most widespread thanks to their hatchling spiders' ability to use ballooning as a means of dispersal.  They spin a long thread from their spinnerets and allow the wind to catch it, carrying them to a new location.  This is a unique ability that the Red-headed Mouse Spider has among Mygalomorphs.   No other  uses it, they disperse on foot. 
   Mouse Spider venom is very similar to that of Funnel-web Spiders.  For that reason care must be taken with Mouse Spiders.  Fortunately, they are not nearly as keen to bite and, more often than not - and, for unknown reasons - they seem to produce a 'dry' bite.  Only once was funnel-web antivenom required, which produced a positive result, and that was in the case of a 19-month old infant that had been bitten by a Mouse Spider. (There is no specific Mouse Spider antivenom.) 
      Eastern Mouse Spider  -  Missulena bradleyi
      Missulena dipsaca

​    
      Missulena insignis     (possible occurrence)
      Red-headed Mouse Spider  -  Missulena occatoria

      

Taxonomy:
​
Phylum:   Arthropoda   (Arthropods)
          > Subphylum:   Chelicerata   (Chelicerates)
                    > Class:   Arachnida   (Arachnids) 
                                        > Order:   Aranea   (Spiders)
                                                  > Suborder:   Mygalomorphae   (Mygalomorphs)
                                                                      > Superfamily:   Avicularioidea   
                                                                                >   Family:   Actinopodidae   (Mouse Spiders)
                                                                                                              > Genus:   Missulena
                                                                                                                        > Species:   M. bradleyi - Eastern Mouse Spider
                                                                                                                        > Species:   M. dipsaca
                                                                                                                        > Species:   M. insignis  ^
                                                                                                                        > Species:   M. occatoria - Red-headed Mouse Spider
 
*  =  likely
^  =  possibly
Note:  Since Murphy and Roberts (2015), the alternative spelling: 'Actinopidae' is cropping up here and there.  Whereas protected under taxonomic rules, it should not be used. 
References  and  links:
​
>      Isbister, G.K.,  (2004).   'Mouse spider bites (Missulena spp.) and their medical importance.'  Med J Aust. 180 (5): 225–227. doi:10.5694/j.1326-5377.2004.tb05890.x. S2CID 37977034.
>      Murphy, J.A.   and Roberts, M.J.,  (2015).   'Spider families of the world and their spinnerets.'    British Arachnological Society, York, volume 1 & 2, pp. i-xii, 1-189; xiii-xvi, 191-553.

​       https://australian.museum/learn/animals/spiders/mouse-spiders/
      https://wsc.nmbe.ch/family/1/Actinopodidae
      https://www.arachne.org.au/01_cms/details.asp?ID=2427

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