Xylographa erratica

The species is a wood-inhabiting lichen whose sterile fungal threads (hyphae) grow through the wood and become lichenized by forming internal plugs of algal cells. As these plugs merge and expand, they can swell when wet and push apart the wood fibres, producing a cracked, "unkempt" surface appearance. The algal partner (photobiont) is a green, rounded (chlorococcoid) alga about 9–20 μm in diameter. The fruiting bodies (ascomata) are small, narrowly to broadly oval (ellipsoid), and typically develop singly, elongating in one direction. The disc may be exposed or partly hidden and can appear flat to concave and brown, with a pale to dark brown margin that is not strongly differentiated from the surrounding tissue. Under the microscope, the asci are 55–75 μm long and mostly 12–15 μm wide, each containing eight oval ascospores that are typically 11–12 μm long and 5–6 μm wide, though occasional spores fall outside this range. Adjacent asexual fruiting structures (conidiomata) produce long, curved, thread-like (filiform) conidia (asexual spores) about 15–20 × about 0.5 μm. The thallus chemistry is characterized by stictic acid as the major lichen substance, with norstictic acid reported as trace or absent.

Xylographa erratica grows on conifer wood, including both coastal driftwood in the intertidal zone and inland wood in forest habitats. It has been reported from humid boreal conifer forests and along coastal beaches up to about 880 m elevation, and is known from scattered localities in northern Europe, northeastern Asia, and western North America between roughly 51° and 60°N latitude. In the continental boreal forests of the Russian Far East it may be locally abundant, and it can occur in the same maritime driftwood habitats as the similar species X. opegraphella.

== References ==