Malmidea coralliformis

The thallus forms a thin, crust-like growth (about 50–70 μm thick) on bark and is densely warted (verrucose), with individual warts about 0.2–0.3 mm high and 0.1–0.3 mm wide that often coalesce and branch; soredia and isidia are absent. The medulla is whitish and reacts K+ (orange). Apothecia (the spore-producing discs) are sessile, rounded and 0.7–1.1 mm in diameter; the disc is brown to dark grey-brown with a thin, biatorine margin of the granifera type. The rim tissue (proper exciple) is hyaline peripherally and internally shows a medullary layer of loosely arranged, periclinally arranged hyphae bearing hydrophobic granules that partly dissolve in potassium hydroxide solution with a greenish-yellow reaction. The subhymenium is brown, the hypothecium (tissue beneath the hymenium) is blackish-brown and K–, and the hymenium is 75–100 μm high. Asci are 60–70 × 13–15 μm. Ascospores number 6–8 per ascus, are colourless, ellipsoid, non-septate and halonate, measuring 10–17 × 6–10 μm. The authors report several unknown xantholepinones as the detectable chemistry and note the absence of atranorin.^[2]

The species is known from northern Thailand (Chiang Mai province), where it grows on tree bark in humid evergreen Dipterocarpus forest around 700 m elevation. The original material was collected along the trail to Monthanthan waterfall in Doi Suthep–Pui National Park.^[2]