Sticherus cunninghamii
(formerly known as Gleichenia cunninghamii)

This is also known as "Umbrella Fern", Tapuwae kotuku, and Waekura.

It is found in many parts of the country, but in the Kaimais I have only found it at higher altitudes.

It is quite distinctive - you'll recognise it when you see it. There is another Sticherus with finer leaves.