Hi Flossiepip, as far as I can see
Ariamnes triangulatus is a NZ species, looking at that Urquhart 1887 paper (
http://rsnz.natlib.govt.nz/volume/rsnz_ ... 002350.pdf, p.7) it's an original description, and the few other mentions of the species I can find give its range as New Zealand, no mention of Australia that I can see. Says it frequents
Leptospermum, and gives Te Karaka as a locality. I'm a bit puzzled though, because Urquhart's illustration (Plate VIII, Fig. 6) shows a spider with a much less elongated abdomen than your one, very like an
Argyrodes. The illustration is of a female, but Urquhart says the male's abdomen "does not differ essentially from female in form or coloration".
Looking at some
Ariamnes pictures online, some of them definitely look like yours (e.g.
https://www.flickr.com/photos/nickadel/22789649421), while others look more like Urquhart's illustration (e.g.
https://nature.berkeley.edu/~gillespie/ ... rodes.html - this page also has some elongated ones, and also talks about
Argyrodes, but the "
A. alepeleke" that is illustrated is an
Ariamnes apparently, even though it has an
Argyrodes-like abdomen).
Ariamnes triangulatus is the only species in the genus listed in The NZ Inventory of Biodiversity (spelled as
Arianme triangulatus).
So in summary, as far as I can make out, your spider definitely definitely looks like an
Ariamnes, but it may be some species other than
triangulatus, unless that species is more variable than Urquhart realised. So maybe yours is a new record for NZ? There's an Australian species,
A. colubrinus, that's supposed to be quite common and could conceivably balloon over, but it looks like it's even more elongated than yours, nor is the colour quite right -
http://www.bowerbird.org.au/observations/53345. There's at least one other Australian species,
A. flagellum, but that doesn't look quite right either.