Lecanactis minutissima

Lecanactis minutissima is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. Found in Sri Lanka, the lichen is characterised by its pale ochraceous thallus and sessile apothecia with dark brown, covered with thick white granular.

Taxonomy
Lecanactis minutissima was formally described by Gothamie Weerakoon and André Aptroot in 2015. The type specimen was collected by the first author in Morningside, Sooriyakanda, on the bark of a dead Syzygium tree.

Description
This lichen has a crustose, non-corticate, and continuous thallus with a dull, pale ochraceous appearance. It grows epiperidermally without a surrounding. The algae in the thallus are. The apothecia are sessile, round to angular or ellipsoidal, with a dark brown measuring approximately 0.2–0.5 mm in width, covered with a thick white granular. The of the apothecia is flush with the disc,, and equally pruinose. The has a thick layer of large crystals. The and  are black, except for a hyaline layer of large crystals on the excipulum's outside. The hamathecium is not, weakly amyloid, with anastomosing. The asci are cylindrical and of the Abietina-type. are hyaline, consistently contain three septa, curved, somewhat, and measure 13–18 by 2–3 μm. Pycnidia were not observed in this species. The lichen's chemistry, as tested with standard chemical spot tests, is negative for UV, C, K, KC, and Pd reactions, and no substances were detected through the use the thin-layer chromatography.

The lichen is most similar to Lecanactis dubia and Lecanographa illecebrosula, but differs from them in ascospore size, apothecium margin characteristics, and chemical reactions.

Habitat and distribution
Lecanactis minutissima is found in wet, mountainous tropical forests, where it grows on the stringy bark of dead trees. At the time of its original publication, it was only known to occur in Sri Lanka.