Its narrow lobes are 0.5–2 millimetres wide, linear or sometimes appearing beaded (moniliform), and branch moderately to densely, primarily in pairs near the thallus edge.

The upper surface appears bright yellowish-green to pale greyish-yellow and is smooth, lacking vegetative reproductive structures like isidia or soredia.

When present, the spore-producing structures (apothecia) are stalked, up to 1 centimetre wide, with discs varying from pale yellowish-brown to dark red-brown.

Small, shiny spore-producing structures (pycnidia) commonly appear at lobe tips, producing rod-shaped to slightly spindle-shaped reproductive cells (conidia) 5–6.5 μm long.

[4] In Chile's Magallanes region, P. angustata characteristically inhabits exposed, smooth bark, particularly on Nothofagus betuloides trees growing at the edges of bogs.