Common on dead kopi (Corynocarpus laevigatus) bark - on standing dead trees and on fallen bark shards. Fruiting bodies externally black, rather hard, internally white.

Determination tentative.

Voucher: P.J. de Lange CH2995 & B. Maxwell, PDD 116647

A well-known bracket but I can't remember the name right now. Soft and flexible, not hard and woody. I will add FUNNZ number once I give it one in the morning.

Back at the Mangapapa Conservation Area, on dead wood of a living tree (tree is pictured too).

The real Polyporus hypomelanus? The visible parts very closely match the description by Cunningham (1965). Notably has the "glabrous and polished ochraceous surface" that my other P. hypomelanus (cf. https://inaturalist.nz/observations/101134380 ) does not have. Also this one does have an acute or even margin, but the margins on all specimens of that other record are inrolled.
This one was on kanuka or manuka, a fallen branch that was still upright, not lying on the ground.
I saw this one (but alas did not photograph) as it developed to maturity over 10 days or so and it started life with a creamy-green gelatinous cap and quite a pronounced, reticulate stipe, which gradually expands into and becomes part of the kidney-shaped thing you see before you. From gloopy and pale it gets black hyphae creeping across the cap on its way to maturity. It's quite an impressive and quick transformation from gloopy and soft tiny-bolete-looking thing to a more typical small woody bracket.
I still have this specimen and it remains polished-looking. It is 5cm across now and the pores are 2-3 per mm, but I guess these dimensions will have shrunk a little as it has dried.