New Zealand has 1157 described spider species, with an estimated total fauna of 2000 species.[1][2][3] Over 97 per cent are endemic, and the rest have been introduced through human activities or were natural wind-borne introductions.[1][3]
The New Zealand spider with the largest leg span is the Nelson cave spider (Spelungula cavernicola), with a leg span of up to 13 centimetres (5.1 in) and a 3 centimetres (1.2 in) body length.
The Australian white-tailed spider, first recorded in New Zealand in 1886, has been falsely attributed as the cause of many necrotising spider bites.[4]
The flat huntsman spider (Delena cancerides), also from Australia, and called the Avondale spider in New Zealand, was accidentally introduced in the early 1920s, possibly in shipments of hardwood logs used for railway sleepers.[5] The huntsman spiders, which are considered harmless to humans, have been collected for use in at least two films.
Very few New Zealand spiders have bites that can cause significant injury to humans, and of these, only one – the katipō – is endemic. Katipō bites have been known to cause systemic effects, such as hypertension, seizure, or coma, though no deaths as a result of katipō bites have been recorded for over 200 years. Its more dangerous close relative, the venomous Australian redback spider, has established a foothold in some parts of New Zealand, notably in Taranaki and Central Otago.[6]