Atracidae is a family of mygalomorph spiders, commonly known as Australian funnel-web spiders or atracids. It has been included as a subfamily of the Hexathelidae, but is now recognised as a separate family. All members of the family are native to Australia. Atracidae consists of three genera: Atrax, Hadronyche, and Illawarra, comprising 35 species. Some members of the family produce venom that is dangerous to humans, and bites by spiders of six of the species have caused severe injuries to victims. The bites of the Sydney funnel-web spider (Atrax robustus) and northern tree-dwelling funnel-web spider (Hadronyche formidabilis) are potentially deadly, but no fatalities have occurred since the introduction of modern first-aid techniques and antivenom.
Description
Spiders in the family Atracidae are medium to large in size, with body lengths ranging from 1 to 5 cm (0.4 to 2.0 in), with one exceptional specimen reaching 8 cm (3.1 in). They have a hairless carapace covering the front part of their bodies. Some atracids have relatively long spinnerets; this is especially true of the Sydney funnel-web spider (A. robustus). Males have a large mating spur projecting from the middle of their second pair of legs. Like other Mygalomorphae – an infraorder of spiders that includes the tropical tarantulas – these spiders have fangs that point straight down the body and do not point towards each other (cf. Araneomorphae). They have ample venom glands that lie entirely within their chelicerae. Their fangs are large and powerful, capable of penetrating fingernails and soft shoes.
Australian funnel-web spiders make their burrows in moist, cool, sheltered habitats – under rocks, in and under rotting logs, and some in rough-barked trees (occasionally meters above ground). They are commonly found in suburban rockeries and shrubberies, rarely in lawns or other open terrain. A burrow characteristically has irregular silk trip-lines radiating from the entrance. Unlike some related trapdoor spiders, they do not build lids to their burrows.
Distribution
The primary range of the Australian funnel-web spiders is the eastern coast of Australia, with specimens found in New South Wales, South Australia, Victoria, Tasmania and Queensland. The only Australian states or territories without members of this family are Western Australia and the Northern Territory.
Taxonomy
The first atracid spider to be described was Hadronyche cerberea, by Carl Ludwig Koch in 1873. Octavius Pickard-Cambridge described another atracid species, A. robustus, four years later. For a considerable time, confusion existed as to the limits of the genera Hadronyche and Atrax, not helped by the destruction of the type specimens of Hadronyche cerberea during World War II. In 1980, Robert J. Raven merged the two genera under Atrax. In 1988, Michael R. Gray separated them again, and in 2010, added a third genus, Illawarra.
The family placement of the group has varied. In 1892, Eugène Simon placed Atrax and Hadronyche in the family Dipluridae. In 1901, Henry R. Hogg considered them to be sufficiently distinctive to form a separate group, which he called "Atraceae" – the basis of the modern family name Atracidae. When in the 1980s, Raven elevated part of Simon's Dipluridae to the family Hexathelidae, he included the atracine group. Molecular phylogenetic studies consistently threw doubt on the monophyly of the Hexathelidae. In 2018, the group was restored to a full family as Atracidae. The following cladogram shows the relationship found between Atracidae and related taxa. Its sister taxon is Actinopodidae.
Genera
, the World Spider Catalog accepts the following genera:
Atrax O. Pickard-Cambridge, 1877 — Australia
Hadronyche L. Koch, 1873 — Australia
Illawarra Gray, 2010 — Australia
Medical significance
Australian funnel-web spiders are one of the most medically significant groups of spiders in the world and are regarded by some to be the most deadly, both in terms of clinical cases and venom toxicity. Six species have caused severe injuries to human victims: the Sydney funnel-web spider (Atrax robustus), the northern tree-dwelling funnel-web spider (H. formidabilis), the southern tree-dwelling funnel-web spider (H. cerberea), the Blue Mountains funnel-web spider (H. versuta), the Darling Downs funnel-web spider (H. infensa), and the Port Macquarie funnel-web spider (H. macquariensis).