Bryoria rigida

Bryoria rigida forms upright, cushion-like tufts that can grow up to 5 cm tall. The species is distinctly bicolorous, with black basal parts and olivaceous-brown apical portions. The main stems are black, reaching up to 0.8 mm in width, and give rise to rigid, evenly branched offshoots. The smaller branchlets, often with an olive-brown tint near their tips, project upwards at sharp angles of about 45° to 65°. Many of these branches have small, spine-like projections with constricted bases.^[2]

The surface of the lichen features black, elongated pores known as pseudocyphellae, which are typically 0.1 mm wide and 0.2–0.7 mm long. These structures are most commonly found on the finer branches. Unlike some related species, B. rigida does not produce soralia or isidia, meaning it lacks specialized structures for asexual reproduction. Other reproductive structures, including apothecia and conidiomata, have not been observed.^[2]

Chemical spot tests tests reveal that the cortex and medulla react positively with para-phenylenediamine (PD+ red-orange), while other standard spot tests yield negative results. The main secondary metabolites identified are fumarprotocetraric acid, with protocetraric acid sometimes present, along with trace amounts of quaesitic and confumarprotocetraric acids, as determined by thin-layer chromatography.^[2]

Bryoria rigida has been recorded from Yunnan, China,^[2] and both Darjeeling and Sikkim in India,^[4] though it is likely more widespread across the Himalayan region. It occurs at elevations between 3,500 and 4,300 m (11,500 and 14,100 ft) in humid, fog-dominated environments. The species grows on both moss-covered rocks and tree branches. The type locality is a mixed montane forest composed of Rhododendron species, Abies delavayi, and Fargesia nitida, where annual precipitation is about 1,874 mm (73.8 in) and the average temperature ranges from 7 to 8 °C (45 to 46 °F).^[2]