Siphula ceratites  

Thallus to 3 cm tall, forming compact tufts, scattered or continuous in extensive patches; branches to 2 mm diam., chalk-white, pale greyish or ivory, ± erect, not or sparingly branched, cylindrical or somewhat flattened, longitudinally folded or furrowed, particularly towards the ± rooting base, smooth, rugose or scabrid-pruinose, solid; apices rounded, not markedly tapered. Soredia and isidia absent. Photobiont chlorococcoid.
Anamorph: not known.
Teleomorph: not known.
Chemistry: cortex C+ violet to yellow-brown (soon fading), K+ yellow to yellow-brown, KC+ yellow-orange to yellow-brown, Pd–; medulla UV± violet-glaucous or ± yellow (siphulin).