Halecania
Crust lichens containing a trebouxioid alga; thallus areolate, verrucose, granular, sorediate, or in some, squamulose; apothecia with an algal rim that resembles that thallus more than the disc, formed of rounded cells and abundant algae, often also with an apparent inner, non-algal rim; hymenium of gel-embedded paraphyses that are often branched in upper portions; hypothecium colourless; asci clavate or cylindrical, similar to Catillaria-type, but the tholus not vertically elongated as in that genus; spores 8 per ascus, with a single septum, surrounded by a thick gelatinous perispore that is usually easily observed.
References: Purvis et al. 1992; Tønsberg 1992.
Halecania viridescens Coppins & P. James
Thallus areolate, the areoles up to 0.2 mm wide, producing soralia on the surface, quickly disintegrating into soredia, the soredia individually 12-20 µ wide; apothecia 0.2-0.4 mm wide, with a thalline rim bearing abundant soredia, the disc dark grey or greyish brown; spores 12-17 (‑20) × 4-6 µ, surrounded by a gelatinous halo 0.5-1 µ thick.
Reactions: P+ orange-red.
Contents: Argopsin.
Habitat: On mossy branches, usually growing among cyanolichens, in waterfall sprayzones. Lower elevations.
Similar Species: Micarea cf. micrococca, when sterile, could be confused with H. viridescens, but has larger soredia that often pile up into coralloid masses, and has a relatively yellowish green colour. Bacidia viridifarinosa may also appear similar, and is known from about 70 km south of the study area, so should be sought. It differs in reacting UV+ orange.
Specimens: Björk 14390.
Local Status: Rare.
Notes: This species is more common on the coast, rare in inland regions.