Hi Andre, I think you're right to pick it as 'different' it has the plastic look of what used to be P. richardii, P. richardii has been divided into a number of species which I haven't got my head around yet, not that it matters as it isn't any of those. P. vestitum is purported to hybridise with all the other native Polystichum so it could be a hybrid but I confess I've always treated it as P. vestitum, despite the coriaceous pinnae and not quite right appearance. If you can get hold of NZ Ferns and Allied Plants, Brownsey and Smith-Dodsworth, there are good drawings of the rhachis scales and indusia which are your best field characters to go on.