Bryostigma huriellae

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Bryostigma huriellae is a tiny fungus that lives on a crusty lichen in South Korea. It belongs to the order Arthoniales, but its exact family placement is uncertain. The species was described in 2020 by lichenologists Sergey Kondratyuk and Jae-Seoun Hur. Its host is the crustose lichen Huriella pohangensis, which is why the fungus has the name huriellae.

The infection spots are very small and often hard to see with the naked eye—usually detectable only under high magnification. On the lichen, these spots may form small groups of spore-producing structures. If the host lichen is damaged, Bryostigma huriellae can be lethal to it. The visible fungal bodies (ascomata) are 70–100 μm across and 50–70 μm thick, usually embedded inside the host. They are typically black, sometimes dark brown at the top and sides, and turn greyish-black in a potassium hydroxide solution, with the brown tone fading. The base remains clear.

Microscopic features include paraphysoids up to about 3 μm in diameter (some widening to 3–4 μm at the tips) and a curvature above the asci tips. The asci themselves are 20–24 by 12–15 μm. The ascospores are hyaline (transparent), 1-septate, and measure 9–13 by 3.5–5.5 μm; one cell tends to be broader. In water, the outer epispore is barely visible.

Bryostigma huriellae is similar to B. parietinarium and B. dokdoense but differs by producing much smaller infection spots and by having distinct microscopic characteristics and a different host preference.