Helen Ranson was looking through some leaf litter when she happened upon a spider she had never seen before.
Ms Ranson, a citizen scientist and part of a group known as BioBlitz, showed her colleague, Canberra's renowned "spider man", Stuart Harris.
"She said to me 'Oh Stuart, what's this?' And I looked at it, and was like, 'Oh no, that's a new species.' I just knew straight away," Mr Harris said.
"We were all over the moon jumping around, you can imagine how they felt.
"They just went out for a day in the bush to maybe find some pretty spiders and then they found a new species."
Mr Harris led the BioBlitz group, who were interested in learning about finding spiders, on an expedition late last year to the Murrah Flora Reserve on the NSW South Coast.
The spider, which on Wednesday was named Maratus sapphirus, was sent to Dr Jurgen Otto, a biologist and peacock spider expert, who confirmed Mr Harris' suspicions.
Mr Harris said the name Maratus sapphirus came from his suggestion of sapphire.
"Maratus which means peacock spider is the name that's given to any spider in that genus [type]," he said.
"Because it was found on the Sapphire coast – the South Coast of NSW – I suggested the name be something to do with sapphire, also because of its colour."
Mr Harris said the chances of finding a new species as a citizen scientist was slim, and that the find was "significant".
In the past nine years, experts have seen a large increase in the number of Maratus species, with many resulting from discoveries by citizen scientists, photographers or other members of the public.
There are 63 species.