You might need the Big Book Of New Zealand Mosses for that one. I remember talking to Roy Perry some years ago, who at the time seemed to be looking at a lot of tree ferns - he was a bit disappointed that Tony Smith didn't think some of the things he had found were worth including in his Moss Flora - I wonder if Roy left any notes on what he had found?
I think I may have found it; Ptychomnion aciculare images and illustrations look spot on http://www.anbg.gov.au/abrs/Mosses_online/images/RS_Ptychomnion_aciculare.jpg
Yep, that looks like it Barry. Well done!