Zwackhiomyces is a genus of fungi that grows parasitically or parasymbiotically (living in close association, sometimes harmfully) on lichens, particularly those containing green algae as their photosynthetic partner. The fungus produces several distinctive microscopic structures that define the genus. The fungus forms small, dark reproductive structures called , which range from 75 to 250
micrometres (μm) in diameter. These structures are typically pear-shaped to spherical and may be either partially or completely embedded in the host lichen's tissue. The outer surface appears black and may be either matte or slightly glossy. The wall () of the fruiting body is brown in colour and distinctively constructed, with pigments concentrated primarily in the spaces between cells (intracellular spaces). At the fruiting body's apex, these pigments form characteristic fine . The wall cells themselves are rounded and may compress against each other, creating a distinctive texture. Inside the fruiting bodies, the fungus produces spore-bearing sacs called
asci, which are cylindrical in shape and relatively rigid in structure. Each ascus typically contains 4, 6, or 8 spores and is equipped with a special opening mechanism () that helps release the spores. The asci are surrounded by thread-like sterile filaments called . These filaments are branched and interconnected, embedded in a gel-like matrix, and relatively stiff in texture. They measure about 6–10 μm long and 1–2 μm wide. The spores () are colourless (
hyaline) and divided into two cells by a cross-wall (
septum). They often show a fine warty surface texture and are usually asymmetrical, with the upper cell being larger and more rounded than the lower cell. The spores typically measure 11–27 μm in length. When treated with certain laboratory stains, the fungal structures show characteristic reactions. The spore-bearing tissue turns reddish-brown with iodine, while the fungal threads (
hyphae) and spore sacs often turn reddish-violet when treated with
methylene blue. The warty spore surfaces may turn blue when treated with
lactophenol blue stain. ==Species==