Cryptothecia methylperlatolica is a corticolous (bark-dwelling) lichen in the family Arthoniaceae. It is a small crustose lichen that forms whitish-gray patches on tree bark in primary rainforest in western Brazil. It is distinguished by the absence of powdery reproductive structures, by linear spore-producing areas that are slightly raised above the surface, and by the presence of 2-O-methylperlatolic acid. It was formally described in 2022 from material collected in a municipal nature park near Porto Velho in Rondônia State, and it remains known only from Brazil.
Cryptothecia methylperlatolica was described in 2022 by André Aptroot from bark-collected material collected in a municipal nature park near Porto Velho, Rondônia, Brazil, at an elevation of about . The holotype (M.E.S. Cáceres 15215 & A. Aptroot) is deposited in the herbarium of the (ISE). Within Cryptothecia, it is characterized by a whitish-gray thallus that lacks soredia, linear spore-producing areas that are slightly raised above the surface, broadly ellipsoid (multi-chambered) ascospores (45âÂÂ50 à27âÂÂ30 üm), and the presence of 2-O-methylperlatolic acid in the thallus. It was considered close to C. albomaculans, which differs in having a thallus and spore-producing areas that are flush with the surface. The specific epithet methylperlatolica refers to 2-O-methylperlatolic acid, the compound detected in the thallus.
The thallus of Cryptothecia methylperlatolica is crustose and continuous, forming a dull, whitish gray patch up to across and up to 0.1 mm thick. It lacks a and soredia, and it is bordered by a narrow brown hyphal about 0.3 mm wide. The is (a member of the green algal genus Trentepohlia). Spore-producing are whitish, linear and flat, 0.5âÂÂ6 à0.3âÂÂ0.5 mm, and somewhat raised above the surrounding thallus. The asci are visible to the naked eye as ochraceous dots, immersed in groups of about 5âÂÂ50 within these spore-producing areas, and are more or less spherical, about 100âÂÂ125 üm in diameter. Ascospores are produced eight per ascus. They are hyaline (colorless), muriform, broadly ellipsoid, and measure 45âÂÂ50 à27âÂÂ30 üm, without a gelatinous sheath. Pycnidia have not been observed. In standard spot tests, the thallus is UVâÂÂ, CâÂÂ, KâÂÂ, KCâ and PâÂÂ. Thin-layer chromatography detectes 2-O-methylperlatolic acid as the main lichen substance.
Cryptothecia methylperlatolica grows on tree bark in primary rain forest at Parque Natural Municipal near Porto Velho (Rondônia, western Brazil), at around elevation. As of its original publication, it had not been reported from outside Brazil. No additional occurrences were reported up to 2025.