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Tree-dwelling funnel-web

Fact Box
Species:
Hadronyche formidabilis (QM)
Previous species name:
Atrax formidabilis (RM)
Family:
Hexathelidae,
formerly Dipluridae
Body length:
female: 45 mm
male: 23 mm
Habitat:
This species builds a burrow in a decaying tree trunk or fence post, usually in rainforest areas; trip-line threads radiate from the burrow entrance
Toxicity:
The venom of males is lethal to humans; this species seems to have venom that is more potent than any other common funnel-web species
Hadronyche formidabilis
Click to enlarge
Male Leg II 'spur'
Click to enlarge
Burrow entrance

The characteristics of this funnel-web species are mostly the same as for the ground-dwelling species, Hadronyche infensa. Only an expert taxonomist can distinguish the females of these two species, but the male Hadronyche formidabilis has a characteristic knob-like spur on the tibia of the second pair of legs. Hadronyche infensa males lack this spur.

The tree-dwelling funnel-web, also known as the Northern Rivers funnel-web, is much less common on the Darling Downs than Hadronyche infensa, although it is relatively common in the forests of the Queensland-New South Wales border. Its venom appears to be slightly more toxic than that of Hadronyche infensa.

Both funnel-web species are found only along the edge of the Toowoomba range and on nearby hills and mountainous areas that receive above average rainfall. Mature males usually appear during or after rain but only over the period late October to early February. They are active at night but seek a dark, moist shelter during the daytime. They quickly die when exposed to drying conditions and will not live for long if they wander into a house or some other similar construction. Having emerged from their burrows, mature males inevitably die within the next few days whereas adult females usually live for more than 5-10 years.

Darling Downs funnel-webs are distinguished from the common trapdoor species in that they are a glossy black colour (not dark brown) and have spinnerets with terminal segments that are longer than they are wide.

When provoked, both sexes rear up (though they do not jump) and drops of venom appear on the ends of their fangs. This tendency to void venom is an important identifying feature of funnel-web spiders.

The neurotoxin in the venom of funnel-web spiders can cause serious illness in an hour or two, the male producing the more potent venom although the volume injected is usually much smaller than for the female. Envenomation can be prevented by the application of a compression bandage over the bite site. An effective antivenom is now available in districts where funnel-webs are known to exist. Surprisingly, virtually all domesticated animals are naturally immune to funnel-web spider venoms.

Spider(s) with a very similar appearance: Hadronyche infensa.


Email Ron Atkinson for more information.    Last updated 30 January 2002.