Lecanactis rubra

Lecanactis rubra is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. Found in Madagascar, it was formally described as a new species in 2009 by Damien Ertz and Emmanuël Sérusiaux. The type specimen was collected by Sérusiaux from the gorge of Manambolo (Mahajanga Province) at an altitude of 300 m. At this location, about 3 km upstream from Bekopaka, in a dry forest with calcareous soil, it was found growing on bark. This lichen is only known to occur at the type locality.

Lecanactis rubra has a cream-coloured, verrucose (pimply), mat thallus that lacks a cortex. The prothallus is dark brown and byssoid (i.e., like teased wool). The ascospores are fusiform (spindle-shaped) with 3 septa, and typically measure 22.5–27.0 by 5.5–6.0 μm. The lichen contains gyrophoric acid, a secondary compound that can be detected using thin-layer chromatography. It also has an unidentified anthraquinone that is present as numerous red crystals in the excipulum (the ring-shaped layer surrounding the spore-bearing hymenium); the specific epithet rubra refers to this characteristic.