Xanthoparmelia amplexula
≡Parmelia amplexula Stirt., Trans. Proc. Roy. Soc. Vict. 17: 69 (1881).
Description : Thallus moderately adnate to adnate on rock, rarely on decorticated wood or soil, 5–10 cm diam. Lobes sparingly imbricate or not, subirregular to sublinear-elongate, irregularly branched, 0.8–2(–3) mm wide, central laciniae flat or absent. Upper surface yellow-green, darkening or blackened towards centre (because of dark-tipped isidia), matt, emaculate, smooth, without areolae or soredia, isidiate. Isidia sparse to densely developed, cylindrical, simple to branched or coralloid, to 2 mm tall, apices syncorticate. Lower surface pale-brown to dark-brown, rhizinate. Rhizines sparse to moderately dense, slender, concolorous with lower surface. Apothecia rare, subpedicellate, 1–5–6 mm diam., disc strongly concave to plane, glossy, dark-brown; thalline exciple thin, persistent, isidiate. Ascospores 7–12 × 5–6 μm. Pycnidia rare. Conidia bifusiform, 6–7 × 0.5 μm.
Chemistry : Cortex K−; medulla K−, C−, KC+ rose-pink, Pd−; containing usnic acid ±loxodin, norlobaridone (major), ±scabrosin 4,4'-diacetate, ±scabrosin 4-acetate 4'-butyrate, ±scabrosin 4,4'-dibutyrate, ±scabrosin 4-acetate 4'-hexanoate; rarely traces of norlobariol, isonorlobaridone, norlobariol methyl ester, connorlobaridone, constipatic and protoconstipatic acid (Elix 1994s: 212).
N: Auckland (Piha, Karekare). S: Nelson (St Arnaud, Lake Rotoiti), Canterbury (Cass), Otago (Cluden, Theatre Flats, Rockburn, Lamb Hill, Port Chalmers, Blackhead, Dunedin). St: On coastal and inland (montane to subalpine) rocks. Known also from Australia, Norfolk I., Lord Howe I., New Caledonia and South Africa (Elix 1994s: 213; Louwhoff & Elix 2002b; McCarthy 2003c, 2006).
Australasian
Illustration : Galloway (1981a: 542, fig. 10 – as Xanthoparmelia scabrosa).
Xanthoparmelia amplexula is characterised by: the saxicolous habit; a foliose thallus; cylindrical isidia; a pale or brown lower surface; and the presence of norlobaridone and ±loxodin in the medulla. It is often confused with X. scabrosa but differs in the nature of the isidia. X. amplexula has slender, syncorticate, cylindrical isidia which may or may not be branched, whereas in X. scabrosa the isidia are epicorticate, warty or globose, become inflated at the apices, and are at length erumpent.
