Flora of New Zealand Series

Type : Lecanora austera Nyl. [Fuscidea austera (Nyl.) P.James] =Fuscidea aggregata (Flot.) V.Wirth & Vězda

Description : Thallus dark-brown to pale creamish or greyish brown, thin or thick, areolate, often developing in patches forming a mosaic, each patch delimited by a thin, black prothallus. Prothallus generally present, black or brown, conspicuous at thallus margins and between areolae. Cephalodia absent. Photobiont, green, trebouxioid. Ascomata apothecia, lecideine to aspicilioid (cryptolecanorine) with margins well developed to absent. Apothecial discs black to dark-brown by virtue of a heavily pigmented epithecium. Hymenium colourless, or streaked with brown pigments, I− (non-amyloid). Paraphyses simple or slightly branched, especially at apices; apices expanded or not, with apical cell sometimes constricted at base, rarely submoniliform (with constricted cells for half the length of the paraphyses), free in K. Asci Teloschistes -type, with strongly amyloid inner wall and a ±well-developed, weakly amyloid, apical gelatinous envelope. Exciple weakly, or well-developed, radiate, brown-pigmented or hyaline in innerparts, barely discernible in immersed apothecia. Hypothecium of anastomosing hyphae, colourless, usually thin. Ascospores colourless, often becoming brownish when mature, simple or rarely 1-septate, thin-walled, ellipsoidal to subarcuate, often truncate, generally less than 11 μm long, sometimes ±constricted at centre, without a halo or gelatinous epispore . Conidiomata pycnidia, immersed in younger parts of thallus, wall brown or pale, opening by a broad ostiole. Conidia bacillar, 3–5 × 0.7–1.5 μm.

Chemistry : Divaricatic, fumarprotocetraric, norstictic present as major compounds (usually only one acid present), or with traces of other depsidones (such as confumarprotocetraric, protocetraric or succinprotocetraric acids), or without any demonstrable chemistry.

Fuscidea is a genus of some 20 species (Kantvilas 2001, 2004g; Kirk et al. 2001), included in the family Fuscideaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005; Reeb et al. 2004). Genera of the Fuscideaceae tend to have dark thalli and apothecia. The family as presently understood comprises six genera [Fuscidea, ? Lettauia, ? Maronea, ? Orphniopsora, ? Ropalospora and ? Sarrameana (Ekman 1993; Brodo & Wirth 1998)] of which Fuscidea, Maronea and Sarrameana are present in New Zealand. Among lecideaceous crustose lichens, species of Fuscidea are rather readily delimited through the characters of unique ascus type (Oberhollenzer & Wirth 1984), paraphyses and chemistry. Thalli in most species have a brownish tint and apothecia are very dark brown to black (hence the generic name). The excipular structure in Fuscidea is very variable; some species have a dark or pale lecideine margin, while others have immersed, aspicilioid (cryptolecanorine) apothecia with no margin or a margin that is vaguely thalline in structure. This variation is described in detail by Oberhollenzer & Wirth (1984) who suggest that the genus is divisible into four groups based on the excipular structure, viz. the cyathoides -group; the kochiana -group; the intercincta -group and the curvula -group. Species are found on siliceous rocks or on acidic tree bark, in cool, moist habitats; coastal, oceanic or alpine. Four species, all saxicolous, are known from New Zealand, three of them apparently restricted to the subantarctic islands (Hertel 1984b, 1985b, 1989; Fryday 2000c, 2003). However, the genus is still very poorly collected and understood here, and it is likely that several species will be found in mainland New Zealand on subalpine to alpine rocks as well as in coastal habitats. Kantvilas (2001, 2004g) gives detailed information on eight species (comprising 10 taxa) known from E Australia and Tasmania, the first comprehensive accounts of the genus from the Southern Hemisphere.

The genus Finerania C.W. Dodge (Dodge 1971: 459) is here tentatively referred to Fuscidea, pending further investigations. If indeed it proves to be conspecific, a case will have to be made for the conservation of Fuscidea, which was described one year after Finerania. However, Fuscidea has been widely used since its description, whereas Finerania has never subsequently been noted, by any lichenologist since Dodge's original description, Dodge's description is also factually inaccurate as he refers (incorrectly) to Trentepohlia as being the photobiont, and to the ascospores as being ellipsoidal and 1-septate (in reality simple and bean-shaped).