We have many, many filmy ferns in Karamea called Hymenophyllum. Kahurangi is a wet place and filmy ferns just love it.
A very common filmy fern here is Hymenophyllum sanguinolentum. Hymenophyllum means membranous leaf and sanguine means blood, so if you dry this little fern out and crush it it smells distinctly of blood or rusty iron.
You will see these all over trees here, they grow on runners, and if it hasn't rained for a few days they start to ball up. The Lake Hanlon walk is a good place to spot them.
Hymenophyllum sanguinolentum is distinct if you look at fertile fronds with a good macro or a microscope, the spores underneath have little membranes or covers holding them in called indusia that have little crests on them, like some sort of a crazy crown. Other similar looking ferns do not have these crowns, so it is a "dead giveaway" if you see these you know that you are looking at this one.
You can see the little crests clearly in the microscopic photo 1. The fern has a distinct zig zag habit which you can see in photo 2.
For more details see https://karamea.nz/web/life/hymenophyllum_sanguinolentum
Enjoy our fern paradise :)