''Hadronyche formidabilis'', the northern tree-dwelling funnel-web spider, is a medically significant

mygalomorph The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to the ...

spider found in

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

and

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. It is also known as the Northern Rivers funnel-web spider or northern funnel-web spider.

Taxonomy

A member of the genus '' Hadronyche'', the northern tree-dwelling funnel-web spider was first described in 1914, by

William Joseph Rainbow William Joseph Rainbow (1856–1919) was an entomologist and arachnologist whose work includes the first catalogue of Australian spiders. Life Rainbow was born in 1856 in Yorkshire, England. His father was a Warrant Officer in the Royal Marines, ...

in the genus ''

Atrax ''Atrax'' is a genus of venomous Australian funnel web spiders that was first described by O. Pickard-Cambridge in 1877 from the type species ''Atrax robustus''. it contains only three species: ''A. robustus'', '' A. sutherlandi'', and '' A. ...

'', having been collected from the vicinity of the

Richmond River The Richmond River is a river situated in the Northern Rivers region of New South Wales, Australia. Course and features The river rises at the northern end of the Richmond Range, near its junction with the McPherson Range, on the Queensl ...

. Rainbow suspected it may have needed to be placed in a genus separate to ''Atrax'' at the time, but demurred due to the lack of male specimens. The species name is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''formidabilis'' "terrifying". Within the genus ''Hadronyche'', it is classified in the heterogeneous ''cerberea'' group, alongside the southern tree-dwelling funnel-web ('' H. cerberea''), the Blue Mountains funnel-web ('' H. versuta'') and 12 other species from southern New South Wales and Victoria.

Description

The northern tree-dwelling funnel-web spider has a glossy black carapace, and matte black or dark brown chelicerae, legs and abdomen. The dorsolateral surface of the abdomen may have a plum- or purplish tinge. The carapace of both sexes is longer and thinner than other members of the genus ''Hadronyche''. With a body length of 40-50 millimetres, it is the largest member of the funnel-web subfamily Atracinae. The species is very similar to the ground-dwelling Darling Downs funnel-web spider ('' Hadronyche infensa''); the male northern tree-dwelling funnel-web spider distinguished by its knobby spur on the tibia of the second pair of legs, which the male Darling Downs funnel-web spider lacks. Trapdoor spiders are more brown overall in colour. Male and female northern tree-dwelling funnel-web spiders rear up and display their fangs when confronted, drops of venom appearing on the ends of their fangs. They are unable to jump. The venom of the species is potentially deadly to humans, and regarded as the most toxic of those in the family Atracidae. A high proportion of bites—five out of eight recorded cases—from the northern tree-dwelling funnel-web spider result in severe symptoms of envenomation. The venom can be successfully treated with the antivenom for the related

Sydney funnel-web spider The Sydney funnel-web spider (''Atrax robustus'') is a species of venomous Mygalomorphae, mygalomorph spider native to eastern Australia, usually found within a radius of Sydney. It is a member of a group of spiders known as Australian funnel- ...

(''Atrax robustus''). Symptoms of envenomation can occur within 15 to 20 minutes. Applying pressure bandages and immobilising the patient can significantly delay the onset of symptoms and remains a critical part of the management of an Australian funnel-web spider bite. Despite the venom lacking the δ-atracotoxin or atraxin of ''A. robustus'', the symptoms are very similar to those from a Sydney funnel-web spider bite. Common symptoms include

diaphoresis Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distribu ...

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

sinus tachycardia Sinus tachycardia is an elevated sinus rhythm characterized by an increase in the rate of electrical impulses arising from the sinoatrial node. In adults, sinus tachycardia is defined as a heart rate greater than 100 beats per minute (bpm). The ...

, muscle spasm or fasciculation, nausea and vomiting, altered consciousness and local pain at the bite site.

Pulmonary oedema Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due to ...

occurs frequently and comes on early. As these spiders are larger than the Sydney funnel-web spider, it may be that they inject greater amounts of venom, making the northern tree-dwelling funnel-web spider possibly the deadliest venomous spider species in the world per volume.

Distribution and habitat

The northern tree-dwelling funnel-web spider is found in eastern Australia from South East Queensland to the Hunter River in New South Wales. This and the southern tree-dwelling funnel-web spider (''

Hadronyche cerberea ''Hadronyche cerberea'', the southern tree-dwelling funnel-web spider, is a venomous Mygalomorphae, mygalomorph spider found in central New South Wales, Australia. Taxonomy and naming German naturalist Ludwig Carl Christian Koch, Ludwig Koch des ...

'') are the only two species of Australian funnel-web spiders that live predominantly in trees. It lives in rotting logs, branches and hollow furrows and pipes of trees, particularly tallowwood (''

Eucalyptus microcorys ''Eucalyptus microcorys'', commonly known as tallowwood, is a species of medium to tall tree that is endemic to eastern Australia. It has rough, fibrous or string bark on the trunk and branches, lance-shaped to egg-shaped adult leaves, flower bud ...

''), as well as in epiphytes. They have been recorded in trees 30 m (100 ft) above the ground. Roving males are encountered after rain and at night between late October and early February. They seek shelter during the day.

Ecology

The arboreal habitat suggests that wood-boring beetles are a main prey item of the northern tree-dwelling funnel-web spider.

References

External links

{{Taxonbar, from=Q2342849 formidabilis Spiders of Australia Spiders described in 1914 Taxa named by William Joseph Rainbow Venomous arthropods Arthropods of New South Wales Arthropods of Queensland