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

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

and

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

. 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 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 five species. Originally placed with the curtain web spiders, it wa ...

'', having been collected from the vicinity of the

Richmond River The Richmond River is a river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may ...

. 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 languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''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 ''Hadronyche infensa'', the Darling Downs funnel-web spider, is a venomous mygalomorph spider, one of a number of Australian funnel-web spiders found in Queensland and New South Wales. Taxonomy The Darling Downs funnel-web spider was describ ...

''); 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 sweat, is the fluid secreted by 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 distributed over much of the ...

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

sinus tachycardia Sinus tachycardia is a sinus rhythm of the heart, with an increased rate of electrical discharge from the sinoatrial node, resulting in a tachycardia, a heart rate that is higher than the upper limit of normal (90–100 beats per minute for adu ...

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

Pulmonary oedema Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

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'') 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

epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

s. 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 Arachnids of Queensland