Calicium adspersum

About

Calicium adspersum is a species of pin lichen in the family Caliciaceae. It forms grey, granular crusts on bark and dead wood, producing black, pin-like fruiting bodies about 0.6–1 mm tall with a yellowish, powdery coating on the head. It was described by Christiaan Hendrik Persoon in 1798 from material on oak wood, and later authors applied a series of alternative names and rank placements to the same taxon in the early 19th century. The species has an antitropical distribution, occurring in temperate regions of both hemispheres, but is generally uncommon and is especially scarce in North America, where few verified collections are known. A Tasmanian subspecies, C. adspersum subsp. australe, differs in its thinner thallus and smaller, grey spores with oblique ridges. Two other subspecies have been described, including one from the Himalayas of India. Under the microscope the species has spirally ridged ascospores and also produces tiny asexual spores (conidia) that can germinate and form fungal colonies in laboratory culture. NatureServe ranks the species as globally vulnerable, linking its decline mainly to the loss and fragmentation of old-growth forest habitat and noting that it may be slow to recover because suitable host trees take many decades to develop.

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