Flora of New Zealand Series

Type : Fuscoderma applanatum (D.J.Galloway & P.M.Jørg.) P.M.Jørg. & D.J.Galloway [=Leioderma applanatum D.J.Galloway & P.M.Jørg.]

Description : Thallus squamulose to subfoliose, ±adnate, ±orbicular, in loosely to closely attached rosettes. Lobes flat to subconvex, discrete to subimbricate with thickened margins, ±delicately pubescent, sometimes sorediate. Upper surface smooth to fissured, shallowly pitted to papillate or somewhat areolate–scabrid, brownish. Medulla white. Lower surface whitish at margins, pale buff to ochre-brown centrally, thinly arachnoid with a short-celled brownish tomentum, rarely with clustered fascicles of white to blue-black simple rhizohyphae. Cyanobiont Nostoc, in clusters. Ascomata apothecia, sessile, constricted at base, laminal, discrete to crowded; disc plane becoming subconvex, orange-brown with persistent pale proper exciple; thalline exciple absent; photobiont layer penetrating apothecium along subhymenium; hymenium I+ blue only around asci, I− in upper parts. Asci without distinct apical amyloid structures. Ascospores ellipsoidal, irregularly ornamented, apiculate at both ends. Conidiomata pycnidia, rare.

Fuscoderma is a genus of five species (Jørgensen & Sipman 2002a: 36, fig. 3; Jørgensen 2003c, 2004e), included in the family Pannariaceae (Eriksson et al. 2004; Pennycook & Galloway 2004) and restricted to New Zealand, Tasmania, Papua New Guinea and Argentina, mostly growing on shrubs and trees in moist, humid habitats. Fuscoderma is clearly related to Leioderma but readily distinguished from it even in the field by its more closely attached, often more adnate thalli, which are also generally thicker and browner. It further differs in several internal characters inlcuding hymenial and ascus iodine reactions. Phylogenetic relationships of Fuscoderma are still enigmatic, but of the genera in the Pannariaceae having a similar apothecial ontogeny (viz., Erioderma, Fuscoderma and Leioderma), Fuscoderma appears to be more closely related to certain groups of taxa in Psoroma s. lat., and Pannaria  s. lat., than to Erioderma or Leioderma (Jørgensen & Galloway 1989: 297). Four species are recorded from New Zealand (Galloway & Jørgensen 1987; Jørgensen & Galloway 1989, 1992b; Jørgensen 1999a, 2003c).