Spiders - destination New Zealand

New Zealand has a rich spider fauna, with over 1100 species known so far. Amazingly, well over a thousand of them are thought to be as unique to New Zealand as kiwi and tuatara. However, some 70 species found here are either introduced in association with humans or have colonised New Zealand by natural processes.

A number of species can be found naturally in both Australia and New Zealand. They probably arrived in New Zealand by a process known as ballooning, where a young spiderling plays out a length of silk which is caught by the breeze and carries the spider aloft. A spider might travel a matter of metres or, if it gets caught up in a suitable weather system, it may even cross the Tasman Sea.  This process has been going on for millions of years and is still going on today. Australian species such as the crab spider Sidymella trapezia is suspected to have naturally dispersed to New Zealand and was first collected here in 2003.

Other spiders have arrived here by anthropogenic dispersal. This means they’ve come here with humans or cargo. Well-known species such as white tailed spiders (Lampona cylindrata and L. murina) and the daddy longlegs (Pholcus phalangioides) have almost certainly reached New Zealand this way. Another recently recognised example is the white porch spider (Cryptachaea gigantipes).

The white porch spider is one of the cobweb spiders (family Theridiidae), a group that includes infamous species such as the redback, katipō and black widow. Fortunately, like the great majority of cobweb spiders, the white porch spider is quite harmless. It was first noted in Auckland around the year 2000. In its native Australia, this spider likes to live on the underside of natural overhangs. In New Zealand, it makes use of similarly shaped structures on houses and other buildings. It has now reached as far south as Upper Hutt.

Te Papa's online Spiders of New Zealand.

Reference:
Smith HM, Vink CJ, Fitzgerald BM, Sirvid PJ (2012)  Redescription and generic placement of the spider Cryptachaea gigantipes (Keyserling, 1890) (Araneae: Theridiidae) and notes on related synanthropic species in Australasia. Zootaxa 3507: 38-56. Online abstract.