Nail Fungus Identification (Poronia punctata)

Poronia punctata is checked by its small, flat, disc-like fruiting bodies on a short stalk.

• Each disc is round to slightly irregular and usually white to pale gray.
• The upper surface shows many tiny black dots, giving a peppered look.
• Fruiting bodies are typically about 0.4-1.2 inches (1-3 cm) across.
• They grow low and close to the substrate, not as tall mushrooms with caps and gills.

Look for the flat white disc with black pinpoints first, since that combination is the fastest visual check.

Poronia punctata shows clear visual changes as its fruiting bodies expand and age.

• Young plant: Early fruiting bodies appear as small, pale, rounded pads on dung, with the dark embedded dots not yet prominent.
• Mature plant: At maturity, each disc becomes broader and flatter, often about 0.4-1 inch (1-2.5 cm) across, with a distinct black-speckled upper surface.
• Fruiting stage: The fertile stage is marked by conspicuous black perithecial openings, flask-shaped spore chambers, scattered across the white to gray disc and visible without magnification.

Poronia punctata is most noticeable when its fruiting bodies appear in warm months on old dung. These small, flat-topped, white to pale gray discs with black pore dots are the main seasonal clue. As they age, the discs often become dingier, crack, or wear away, making older specimens less distinct. Outside the fruiting period, there is usually little visible above the substrate to identify.

Poronia punctata is known from Europe and has also been recorded in parts of North America. It is most often found on old dung in short-grazed grassland, especially pasture used by horses or cattle. That habitat is a strong identification clue. Finding it on weathered dung in open grassland helps separate it from many small black fungi that grow on wood, soil, or leaf litter instead.

Poronia punctata is a dung-inhabiting mushroom, so the main safety concern is misidentification and handling rather than known toxicity from the fungus itself.

• Wrong mushroom risk: Any wild mushroom can be confused with another species. For humans, ingestion is the main hazard if identification is wrong.
• Contaminated substrate: It grows on animal dung. For humans and pets, contact with the fruiting bodies or nearby substrate can expose skin to manure residues and microbes; ingestion is the clearer risk.