Chrysothrix palaeophila

The species is characterised by an endophloeodal (immersed) thallus, barely visible as a bleaching of the bark substrate. It has a unicellular green algal photobiont, with their spherical cells dispersed or aggregated in chains. The apothecia of the lichen are scattered, measuring 0.1–0.3 mm wide, convex to more or less spherical in shape, and typically densely covered with yellow to yellow-green pruina. The ascospores are fusiform (spindle-shaped) to ellipsoid, contain three septa, and measure 10–15 by 2.5–4 μm.^[2]

Chrysothrix palaeophila contains vulpinic acid as a major secondary metabolite (lichen product), along with pulvinic dilactone in minor or trace amounts.^[2]

This species has a restricted distribution, known only from a few collections in Tasmania. It is found in cool temperate rainforest or wet eucalypt forest, predominantly on ancient conifers such as Lagarostrobos franklinii and Athrotaxis selaginoides, as well as on Eucalyptus obliqua.^[2] In 2012, Chrysothrix palaeophila, described as "very rare", was known to occur in four locations.^[3]

Chrysothrix palaeophila grows in fissures on dry, cracked wood and dry, fibrous bark, which are environments that are typically devoid of other lichens. This cryptic nature suggests it may have been overlooked in other locations.^[2] Its growth appears to be restricted to the trunks of ancient trees.^[3]