Thelotrema
Crustose lichens containing a trentepohlioid alga; thallus smooth, scurfy, sorediate or immersed; apothecia sunken deep in thalline warts or partly surrounded by scurfy thalline material, the rim formed of a thin layer of intertwining hyphae, sometimes splitting radially, separating from the wall of the thalline wart and arching over the disc; hymenium formed of straight, unbranched paraphyses evenly spaced in thick gel; hypothecium colourless; asci narrowly clavate, thin walled and with a modestly thickened tholus, IKI-; spores 1-8 per ascus, colourless or light brown, elliptical to elliptic-fusiform, with transverse septae only, or muriform, the septae often unevenly thickened so that the cells are elliptical in shape.
References: Purvis et al. 1992.
Thelotrema lepadinum (Ach.) Ach.
Thallus creamy white, smooth and extensive, waxy; apothecia 1-2 mm wide, housed in barnacle-like warts opening by a gaping hole about 0.3-0.5 mm wide, the inner rim visible within as a papery margin curling over the disc, usually rent into 3-4 segments; hymenium 140-190 µ high, colourless; spores muriform with 10-15 transverse and 1-3 longitudinal septae, 60-135 × 15-25 µ.
Reactions: Spot tests all negative.
Contents: No known lichen substances.
Habitat: On mostly smooth bark of conifers or broadleaf trees in very humid, oldgrowth forests. Lower elevations.
Similar Species: Unmistakable for the barnacle-like apothecial warts and presence on smooth bark.
Specimens: Goward 96-895, 96-951.
Local Status: Rare.