


Australian Biological Resources Study
| Checklist of the Lichens of Australia and its Island Territories | ||
| Introduction | A–D | E–O | P–R | S–Z | Oceanic Islands | References | ||
| Umbilicaria decussata (Vill.) Zahlbr. | ||
| Cat. Lich. Univ. 8: 490 (1932) Lichen decussatus Vill., Hist. Pl. Dauphine 3: 964, pl. LV (1789). T: Dauphine (Hauts Alpes), France; holo: the illustration in Villars. | ||
| Thallus usually monophyllous, orbicular, 1–8 cm wide,  rarely polyphyllous, coriaceous, rigid; margins entire or variously incised,  becoming ±torn, often upturned. Upper surface dull,  pale to dark grey or brownish grey, scabrid, markedly faveolate-reticulate,  with sharp ridges radiating from the elevated umbo, decreasing towards the  margins, with a whitish coarsely granular necral layer centrally or extending  onto ridges, with or without thick blackened and glossy margins. Isidia and  soredia absent. Lower surface grey to pale brown, smooth, rarely with very fine  wrinkles, commonly bullate, ±continuously covered with sooty black  thalloconidia with a narrow grey to pale brown or occasionally patchy  peripheral zone; rhizinomorphs absent. Thalloconidia single-celled, spherical  to ovoid, 6–8 µm diam. Apothecia rare in Australian material, scattered, 1–3 mm  diam., black, initially adnate, becoming substipitate; disc plane, not gyrose,  often with a central column of sterile tissue (omphalodisc), becoming convex  and distorted with age. Ascospores simple, ellipsoidal, colourless, 6–13 × 3–7  µm (only immature ascospores seen). Pycnidia not seen for Australian material;  Wei & Jiang (1993) reported bacilliform conidia 2–3 × 1 µm. CHEMISTRY: Medulla K–, C+ red or C–, KC+ red or KC–, P–; containing gyrophoric acid (major), lecanoric acid (minor). Narui et al. (1996) reported ovoic acid (minor), but this has not been confirmed for Australian specimens. | ||
| Occurs in N.S.W., A.C.T., Vic. and Tas.; grows on exposed, windswept, alpine rocks or on sheltered rock outcrops. Also in North and South America, Europe, northern Asia, Antarctica and New Zealand. | ||
| Louwhoff (2009c) | ||
| Checklist Index | 
| Introduction | A–D | E–O | P–R | S–Z | Oceanic Islands | References | 
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