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.

Maratus sapphirus was found in the Sapphire Coast of NSW. Credit: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.