Thelotrema hnatiukii

About

Thelotrema hnatiukii is a species of crustose lichen in the family Graphidaceae. It grows on tree bark on Aldabra (Seychelles) and has a pale grey thallus that lies mostly within the outer bark, so the lichen can be easy to miss. The round fruiting bodies (ascocarps) are 0.5–0.8 mm across, with a slightly raised margin around a pore 0.2–0.5 mm wide; when dry, the brown rim tissue is often visible through the opening (ostiole). Each ascus contains eight colourless ascospores that are somewhat muriform and measure about 12 × 9 to 17 × 7 μm; most spores have 4–6 main cross-walls, and some segments are also split lengthwise. The thallus contains stictic acid and turns yellow when tested with potassium hydroxide solution.

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