Malmidea perplexa

The thallus is crust-like, continuous and smooth, about 100–250 μm thick, dull to slightly shiny and grey-green; soredia and isidia are absent. The medulla is whitish and K–. The photobiont is chlorococcoid with cells 6–8 μm in diameter. Apothecia are sessile, rounded, 0.4–0.7 mm across and 150–180 μm high; the disc is plane to slightly convex and brown-grey to sooty, bordered by a thin biatorine margin of the piperis type that is about 20 μm thick, slightly prominent and whitish-grey to dark brownish-grey. The proper exciple is hyaline and internally lacks the medullary layer (about 30–70 μm wide) and lacks hydrophobic granules; the subhymenium is about 20 μm high and light brown, the hymenium 75–120 μm and hyaline, and the hypothecium 30–80 μm and hyaline, K–; the epihymenium is indistinct. Asci measure 50–65 × 10–15 μm. Ascospores number 6–8 per ascus, are colourless, ellipsoid, non-septate and halonate, 9–13 × 5–7 μm with an about 0.5-μm halo. No lichen substances were detected by thin-layer chromatography or high-performance liquid chromatography.^[2]

The species grows on tree bark in evergreen forests in Thailand (including sites in Chiang Mai and Khao Yai and the Kaeng Krachan area) and is also recorded from south-eastern Brazil (São Paulo), at roughly 520–1000 m elevation.^[2]