Saxicolous on andesite rock - common on bare rocks near permanent snow line. Thallus up to 60 mm diameter (usually less), upper surface pale greyish-white, conspicuously white-pruinose,lower surface and margins densely covered in black rhizinomorph felt (rhizinomorphs protruding along thallus margins). Fits this species well except that all material seen had apothecia. Galloway (2007) notes 'an absence of apothecia' -is this diagnostic of this species or did he mean he hadn't seen any. Either way this is the best name I could come up with for this common high alpine Umbilicaria on Mt Ruapehu. Voucher in AK. Images were taken for me by Jeremy R. Rolfe Galloway, D.J. 2007: Flora of New Zealand; Lichens, including lichen-forming and lichenicolous fungi. Revised second edition.1 ed. Lincoln, Manaaki Whenua Press. 1006 p.