Hypotrachyna laevigata

Thallus loosely adnate, to 15 cm diam.; lobes crowded, becoming ± imbricate, linear to sublinear, dichotomously to subdichotomously or rarely irregularly branched, (1–) 2–6 (–8) mm broad, ± subrevolute; margins mostly entire, sometimes irregularly lobulate or laciniate-dissected, not ciliate; apices truncate, sometimes pointed; lobe axils sinuous or V-shaped; upper surface glaucous to bluish grey-white or grey-green, smooth or small-pitted, shiny or matt, maculate, sorediate; soralia terminal to subterminal, rarely cuff-shaped, often globose; soredia granular, grey or blackened; medulla white; lower surface black with a brown margin, shiny, smooth, densely rhizinate; rhizines moderately to densely branched, continuing to lobe margins and often protruding beyond, sometimes as a dense mat. Apothecia rare, laminal, stalked; disc (1–) 3–10 mm diam., dark brown; exciple mostly sorediate, entire, becoming torn on larger apothecia. Ascospores rare, reported as 18–21 × 9–13 μm but measured as 12.5–13.5 × ca 5 μm in British material. Pycnidia subterminal and laminal; conidia bifusiform, 4–6 (–7.5) × ca 1 μm. Cortex K+ yellow, medulla C+ pale orange, K–, KC+ deep orange, Pd–, UV+ bluish-grey or UV– (atranorin, chloroatranorin, barbatic acid [major], 4-O- demethylbarbatic acid [submajor], obtusatic acid [trace], norobtusatic acid [trace]).

This is a variable species but in general is characterised by the maculate upper surface, globose soralia and a white medulla, the latter clearly separates H. laevigata from H. endochlora. This also is a polyphyletic species and African populations have been assigned to a separate species, H. nyandaruaensis (Kirika et al. 2019). This provides some indication that H. laevigata populations growing in disjunct geographic areas may correspond to distinct lineages.