Tetramelas flindersianus is a saxicolous (rock-dwelling) crustose lichen species in the family Physciaceae. First described scientifically in 2020, it is found in Australia.
The type specimen of the lichen was collected on Tasmania's Flinders Island. It was found approximately southeast of West Point, either on or near a siliceous rock outcrop. Tetramelas flindersianus, is named after its type locality, Flinders Island in Tasmania. It is similar to Tetramelas filsonii, but is distinct in having a non-amyloid , narrower , and containing only atranorin.
The thallus of Tetramelas flindersianus is and , growing up to 60 mm wide and 1 mm thick. The , ranging from 1âÂÂ2.5 mm wide, can be scattered or contiguous, sometimes aggregating to form a secondary somewhat (scaly) crust that occasionally lifts off the . The upper surface of the thallus is off-white to grey-white, dull, and in parts, with no visible . The cells measure 8âÂÂ23 üm wide, and the is white, lacking crystals of calcium oxalate.
The are 0.3âÂÂ1 mm wide, in type, and can be separate or in small groups, broadly to , with a black, non-powdery (), flat to weakly convex . The proper is prominent, , and shiny, measuring 40âÂÂ50 üm thick. The is dark brown to dark olive-brown, while the beneath is brown to brown-black, forming a central plug. The is 65âÂÂ90 üm thick, colourless, and the beneath it is pale brown, 20âÂÂ35 üm thick. are 1.5âÂÂ2.0 üm wide, sparsely branched, with dark brown capped tips. The are of the Bacidia type, containing eight spores. The are initially of the Callispora- or Physconia-types, then of the Buellia-type, brown, ellipsoid to broadly or bottle-shaped, measuring 13âÂÂ20 by 5âÂÂ7 üm, and the outer spore-wall is . are immersed, , with measuring 5âÂÂ7 by 0.7âÂÂ1 üm. Chemically, the thallus contains atranorin as a major lichen product.
Tetramelas flindersianus has been found on hard, siliceous rocks such as quartzite at two locations on Flinders Island, Tasmania, and one in Victoria. It is associated with typical nearshore lichen species like Buellia stellulata, Caloplaca cribrosa, Catillaria austrolittoralis, Lecanora subcoarctata, Pertusaria xanthoplaca, Rinodina blastidiata, and Tylothallia verrucosa.