Tetramelas flindersianus

Tetramelas flindersianus is a saxicolous (rock-dwelling) crustose lichen species in the family Physciaceae. First described scientifically in 2020, it is found in Australia.

Taxonomy
The type specimen of the lichen was collected on Tasmania's Flinders Island. It was found approximately 5.8 km 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.

Description
The thallus of Tetramelas flindersianus is and, growing up to 60 mm wide and 1 mm thick. The, ranging from 1–2.5 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 8–23 μm wide, and the  is white, lacking crystals of calcium oxalate.

The are 0.3–1 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 40–50 μm thick. The is dark brown to dark olive-brown, while the  beneath is brown to brown-black, forming a central plug. The is 65–90 μm thick, colourless, and the  beneath it is pale brown, 20–35 μm thick. are 1.5–2.0 μm 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 13–20 by 5–7 μm, and the outer spore-wall is. are immersed,, with  measuring 5–7 by 0.7–1 μm. Chemically, the thallus contains atranorin as a major lichen product.

Habitat and distribution
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.