Flora of New Zealand Series

Thallus crustose, uniform, spreading, smooth to somewhat unevenverrucose, or with lobulate isidia, greenish-white or pale grey-white, corticolous, muscicolous or rarely saxicolous. Photobiont green, Chlorococcoid. Apothecia sessile to ± pedicellate usually constricted at base, to 4 mm diam., disc yellow or golden, ochraceous to ± blackened, ± pruinose, often contorted with sterile tissue, plane to subconvex, margins thin or thick, yellow, orange, ochraceous or rarely black, entire to crenate or ± inflexed. Asci of Brigantiaea -type, without an external apical cap but with thick, I+ blue-staining external wall layer, inner apical apparatus present and inner wall layers amyloid (I+ blue). Ascospores 1, exceptionally 2 per ascus, ellipsoid, colourless, mature spores brownish, muriform, large, to 150 µm long (immature spores may be much smaller). Paraphyses thin, with a few anastomoses and branches, not distinctly thickened at apices. Epithecium and excipulum encrusted with yellowish crystals (K+ red-purple). Thallus K+ yellow (atranorin and chloratranorin).

Brigantiaea is a genus of c. 12 species from both Northern and Southern Hemispheres placed in the monotypic family Brigantiaceae [Hafellner and Bellemère Nova Hedwigia 35: 237-261(1982)]. Although described by Trevisan in the mid 19th century [ Riv. Period. Accad. Padova 1: 249(1853); Linnaea 12: 283-298(1856)] it is still often included in the genus Lopadium, although with hesitation [see Santesson Symb. bot. upsal. 12: 521-523(1952)]. The genus is discussed by Poelt and Vĕzda [ Bestimmungsschl. eur. Flecht. Erg. II: 116(1981)] and by Hafellner and Bellemère (loc. cit.). Four species are recognised in New Zealand. Myxodictyon described by Massalongo [ Atti R. Ist. veneto Sci. ser. 3, 5: 254 (1860)] is a later synonym of Brigantiaea. See also Hafellner [ Lichenologist 15: 263-266 (1983)].