Pseudocyphellaria haywardiorum

The thallus of Pseudocyphellaria haywardiorum is more or less circular, measuring 30–80 mm in diameter. This lichen loosely attaches from its edges to its centre. The edges of the thallus appear to rise slightly and display rounded lobes, spanning 2–20 mm in length and 4–25 mm in width. These lobes stand apart but touch each other and have a complex overlapping pattern. The lichen's margins are sinuous, rising weakly with an irregular formation ranging from finely to coarsely jagged. The underbelly of the lichen occasionally presents soredia – small reproductive propagules – and has a greyish-white, eroded appearance. The upper surface showcases a spectrum of colours from dark grey-blue to brown-black, particularly becoming darker at the lobe tips when moist. When dry, the central area can vary from dark olive-brown to a pale yellowish tint with greyish edges. The surface texture can be flat or slightly wavy, with the tips more wrinkled and the remainder distinctly dotted. Additionally, the upper surface is matte, ranging from smooth to minutely spiderweb-like in parts. Depending on its state, it feels either leathery to brittle when dry or soft and limp when wet. It is sorediate, and it lacks phyllidia or pseudocyphellae. Small, irregular light buff-coloured spots (maculae) can be seen, forming a mesh-like patterns towards the lobe tips. …

On Raoul Island, it is known from fragmentary specimens collected from amongst the debris of Kermadec pōhutukawa that were toppled by a cyclone, suggesting that in that location it inhabits the upper tree canopy. In Kohimarama, where it is quite rare, it has been found growing on the trunks of cabbage trees and on fallen dead branches.