Xylographa soralifera

Xylographa soralifera is a species of bark-dwelling, crustose lichen in the family Xylographaceae. It was described in 2008 and belongs to the X. vitiligo complex, but differs from that species in both morphology and chemistry, including its production of fumarprotocetraric acid.

Taxonomy

Xylographa soralifera was described as new to science by Håkon Holien and Tor Tønsberg in 2008. The holotype is from Kittitas County, Washington, near Cle Elum; roughly elevation, where it was growing on conifer wood. In the same paper the authors clarified long-standing confusion within the X. vitiligo species complex by typifying several historical names.
The new species was set apart from X. vitiligo on the basis of its typically thallus with convex, mostly pale soralia and by its fumarprotocetraric acid chemistry; X. vitiligo instead has a poorly delimited thallus with excavate soralia and contains stictic acid.

Description

The thallus of Xylographa soralifera is crustose and occurs within to on the surface of the wood. It is usually distinctly, and sorediate—producing powdery propagules. Soralia are whitish to greenish, mostly convex, often with a thin pale rim, and about 0.3–0.6 mm across; they may coalesce. Soredia are comparatively coarse. The thallus is C−, K− and PD− in spot tests, while the soralia are PD+ ; fumarprotocetraric acid is confirmed by thin-layer chromatography.
Fruiting bodies may be present or absent; when present they are round to narrowly elliptic, solitary or clustered, with a pale brown to flesh-colored that is flat to strongly concave. Typical dimensions are about 0.1–0.3 × 0.2–0.8 mm. Asci are cylindrical to more or less club shaped with eight hyaline, simple ellipsoid to ovoid ascospores. The is a green coccoid alga.
Separation from similar taxa: compared with X. vitiligo, X. soralifera usually shows clearly convex areoles and soralia, and the two differ chemically as noted above. Other sorediate, wood-associated species with overlapping chemistry can occur in similar habitats—e.g., Mycoblastus fucatus, Ramboldia cinnabarina, and Pertusaria pupillaris —but these differ in thallus color, soralia form, and chemistry.

Habitat and distribution

Xylographa soralifera grows on wood, most frequently on slowly decomposing, decorticated logs and stumps in relatively open forest. In Norway it is most often on spruce and Scots pine, and more rarely on wood of downy birch, common juniper and goat willow. In North America it occurs on wood—and only rarely on bark—of several conifers including western larch, pine, Douglas fir, western redcedar and western hemlock.
The species has a northern and/or alpine tendency. In Europe it is known from Norway, Sweden, and the Italian Alps. In North America it is recorded from the Pacific Northwest and interior mountains—Washington and Montana in the United States, British Columbia in Canada—and farther south at higher elevations in Arizona. Documented sites span roughly in elevation. The authors also note that Pacific coast driftwood in Washington and southwestern British Columbia commonly bears X. vitiligo, whereas X. soralifera has yet to be found there.