Its distinct elongated thallus and small brown ascospores set it apart from other similar lichen species.

The species epithet pinnatum is derived from the Latin word for "feathered" and refers to the pinnate branching pattern of the thallus.

The type specimen was collected in 1988 from English Peaks in the Northern Province of Papua New Guinea, at 3,600 m (11,800 ft) above sea level.

[2] The upper surface of the thallus is pale gray to white, with a smooth or rugose texture that may appear slightly wrinkled above the apothecia.

According to the available data, it grows on the trunks of Dacrycarpus trees in stunted, Dacrycarpus-dominated forests around Mount Kenevi.