Flora of New Zealand Series

=Siphula medioxima Nyl., Lich. Nov. Zel.: 15 (1888).

≡Nylanderiella medioxima (Nyl.) Hue, Ann. Mycol. 12 (6): 509 (1914).

Lectotype: New Zealand. Greymouth, supra terram, 1886, R. Helms 127 – H-NYL 40178 [fide Galloway (1985a: 524)]. Isolectotype – W (ex Herb. Lojkanum).

Siphula medioxima. Lectotype: New Zealand, sine loco [probably near Greymouth], R. Helms 47 – W (ex Herb. Lojkanum) [fide Kantvilas (1998b: 120)].

Description : Flora (1985: 523).

Chemistry : Cortex and medulla K+ yellow to brownish red, C−, KC−, Pd+ yellow-orange, UV−; containing thamnolic acid and traces of an unidentified compound.

N: Northland (Herekino Gorge, Great Barrier I.). South Auckland (Hunua Ra., Mt Moehau,Table Mountain, Kaitarakihi, Coromandel Ra., Te Aroha, Kaimai Ra.), Gisborne (Lake Ruapani), Wellington (Riapehu, Tararua Ra., Rimutaka Ra.). S: Nelson (Pakawau, Mt Arthur, Lead Hills, Cobb Ridge, St Arnaud Ra., Travers Valley), Marlborough (Mt Stokes), Westland (Denniston and Stockton Plateaux), Canterbury (Lewis Pass, Arthur's Pass, Mt Cook), Otago (Mt Brewster Haast Pass, Blue River, Forgotten River, Humboldt Mts, The Remarkables, Old Man Ra., Silver Peaks, Maungatua), Southland (Key Summit, Resolution I., above Cascade Cove Dusky Sound, near Lake Poteriteri, Borland Saddle, Longwood Ra.). St: (Mt Anglem, Glory Cove Paterson Inlet, Table Hill, Mt Allen, Tin Ra., Disappointment Cove, Cook's Arm, Fraser Peaks, Fright Cove Port Pegasus, Smith's Lookout). A: (Musgrave Inlet). On soil, and among mosses in subalpine to high-alpine grassland, in scrub and bog associations above treeline, among mosses on tree stumps and at the base of forest trees, s.l. to 1600 m. Widely distributed in the palaeotropics being known from South and East Africa, Réunion, Madagascar, Central America, Venezuela, the Caribbean, Brazil, Borneo, Japan, China, Taiwan, Papua New Guinea, and Tasmania (Bratt 1972, 1976a; Mathey 1974; Kantvilas 1994b, 1998b, 2002a; Aptroot 2002e; Kantvilas & Elix 2002; McCarthy 2003c, 2006; Kantvilas et al. 2005a).

Pantropical

Exsiccati : Moberg (1994a: No. 143); Vězda (1997f: No. 317; 1998b: No. 379).

Illustrations : Mathey (1974: 811, fig. 21; 812, figs 24–26; 813, figs 27, 28); Malcolm & Galloway (1997: 142); Kantvilas (1998b: 122, fig. 1); Kantvilas & Jarman (1999: 142); Malcolm & Malcolm (2000: 41, 83, 91).

Siphula decumbens is characterised by: the terricolous, rarely muscicolous habit; the whitish thallus; the generally broad, scabrid (×10 lens) lobes that are frequently dorsiventral (with one side more markedly scabrid than the other) and irregularly branched and lobed in several planes; the lobulate, crenulate or lacerate apices; and the presence of thamnolic acid (K+ bright-yellow turning brownish red). The species is very variable over a range of ecologies, exhibiting considerable morphological variation. Specimens from alpine soils form very densely crowded swards of erect or decumbent broad lobes with broadly rounded or crenulate apices. Abrasion from trampling (by either animals or trampers along tracks) leads to proliferation of regenerating lobules and nodules, and also to carriage of thallus fragments to lower altitudes in forest and scrub, where the increased shelter and humidity allow thalline lobes to become more elongate and distinctively lacerate-fenestrate (Galloway 1985a: 524; Kantvilas 1996c: 121).