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Toowoomba trapdoor

Fact Box
Euoplos species (QM)
(previously considered to be an Arbanitis species or Aganippe berlandi; see notes below)
formerly Ctenizidae
Body length:
female: 35 mm
male: 26 mm
In a burrow with a neatly fitting door; males wander above ground at night in autumn
The venom of this species seems to have low toxicity for humans but males may exhibit an aggressive stance as a defence against potential predators and the female during mating
Euoplos species
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The female
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The male
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Closed burrow
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Open burrow
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A verified female

Opinions as to the identity of the trapdoor spider found in large numbers in and around Toowoomba have changed considerably during the last 30 years. Initially, it was thought by Main to be Arbanitis variabilis but the photos and description of Aganippe berlandi in Ramon Mascord's 1980 book, "Spiders of Australia", indicated this was more likely to be the correct scientific name for this species, although the Aganippe genus has now been renamed Idiosoma and has a distinctly different eye arrangement. However, subsequent mygalomorph revisions, particularly by Dr. Robert Raven (1985 and 2005) of the Queensland Museum, transferred to the genus Euoplos many species originally considered to be Arbanitis species. The Toowoomba Euoplos trapdoor shares with Idiosoma berlandi the tendency to make thick plug doors when on creek banks or in black soil locations but thin doors woven from dry grass leaves in other places. It differs from I. berlandi in that it lacks a visible pair of sigilla (small depressions) on the upper surface of the abdomen which can easily be seen on I. berlandi. Another distinctive feature of Euoplos is the fact that it has a fovea (a groove that runs across the centre of the upper side of the cephalothorax) that is deep and curves forward whereas that of Arbanitis species is not significantly curved.

The Toowoomba trapdoor is found widely across the Darling Downs and can tolerate relatively dry open grassland areas, unlike funnel-web spiders. The female rarely leaves the burrow but large numbers of mature males do so to search for mates during autumn and early winter, usually appearing during or after periods of rain.

The male is a much darker brown than the female but always brown not shiny black like all funnel-webs. It has a characteristic double spur on the inside of the tibia of the first pair of legs.

Males rear up when provoked but do not readily yield venom as funnel-web spiders do.

Spider(s) with a very similar appearance: Euoplos variabilis flavomaculata, Cataxia spinipectoris, Namea salanitri, Aname barrema and Arbanitis species.

Email Ron Atkinson for more information.    Last updated 24 April 2018.