Chaenotheca is a genus of lichen-forming fungi in the family Coniocybaceae. The reproduction structures are a mass of loose ascospores that are enclosed by a cup-shaped exciple sitting on top of a tiny stalk, having the appearance of a dressmaker's pin (called a mazaedium), hence the common name pin lichen. Genus members are also commonly called needle lichens. The genus has a worldwide distribution, with the greatest diversity in the temperate forests of the northern hemisphere, though species have also been recorded from the southern hemisphere including Australia, New Zealand, and South America. Species of Chaenotheca are small, inconspicuous lichens that grow mainly on bark and decaying wood in sheltered, humid, low-light microhabitats such as old-growth and ancient woodland, and are considered indicators of ecological continuity in forest environments.

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