Siphula decumbens
Synonyms
Siphula medioxima Nyl., Nylanderiella medioxima (Nyl.) Hu
Family
Icmadophilaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Fruticose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
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).
Distribution
North Island: Northland (Herekino Gorge, Great Barrier Island). South Auckland (Hunua Range, Mt Moehau, Table Mountain, Kaitarakihi, Coromandel Range, Te Aroha, Kaimai Range), Gisborne (Lake Ruapani), Wellington (Riapehu, Tararua Range, Rimutaka Range). South Island: Nelson (Pakawau, Mt Arthur, Lead Hills, Cobb Ridge, St Arnaud Range, 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 Range, Silver Peaks, Maungatua), Southland (Key Summit, Resolution Island, above Cascade Cove Dusky Sound, near Lake Poteriteri, Borland Saddle, Longwood Range). Stewart Island: (Mt Anglem, Glory Cove Paterson Inlet, Table Hill, Mt Allen, Tin Range., Disappointment Cove, Cook’s Arm, Fraser Peaks, Fright Cove Port Pegasus, Smith’s Lookout). Auckland Islands: (Musgrave Inlet).
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.
Habitat
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.
Siphula decumbens is the most widespread species of Siphula in New Zealand and also the most variable. It occupies a variety of habitats from subalpine soils at sea level around Foveaux Strait and on Stewart Island, to alpine soils in most mountainous areas of South Island, to epiphytic moss communities on tree trunks and stumps in sites in north Westland, Nelson, the Coromandel Range, Great Barrier Island, and North Auckland. When growing among bryophytes in shaded, ± humid habitats, thalli of S. decumbens are thinner, flatter, more delicate, marginally lacerate-fenestrate with a granularareolate surface with a pronounced greenish or blue-green colour. Forms from exposed alpine soils are shorter, thicker, more coriaceous and crowded-congested, and may yet prove to be specifically distinct. In some alpine areas along tracks well used by trampers and climbers, thalli of S. decumbens are fragmented and dispersed in the soil at the side of the tracks. In such situations it is possible to observe a change in the morphology of S. decumbens from the alpine grassland type, to the lacerate-fenestrate type characteristic of forest conditions, as fragments are carried down through subalpine scrub into the upper reaches of the forest and establish there in damper and more shaded conditions. It is possible, too, that in certain areas, trampling by deer also influences the distribution of this species.
Detailed description
Thallus lobes variable, narrow, 2-6 mm wide, 0.3-3(-4) cm tall, ± terete or flattened, rarely simple, strap-like, margins entire or variously notched and incised, apices rounded, furcate or irregularly pectinate, ± unilaterally thickened, crowded, congested. Surface ± smooth, coriaceous to roughened, scabrid-areolate or furrowed, in humid, low-light sites often ± fenestrate with ragged, lacerate margins, chalky white in subalpine exposed sites, becoming greenish in sheltered, humid or shaded sites, 0.3 mm thick, smoother and more coriaceous in exposed subalpine habitats, 0.05-0.1 mm thick in shade forms.
Chemistry: Cortex and medulla K+ yellow to brownish red, C−, KC−, Pd+ yellow-orange, UV−; containing thamnolic acid and traces of an unidentified compound.
Substrate
Terricolous, rarely muscicolous
Etymology
decumbens: From the Latin decumbere ‘to lie down, recline’, in botany refers to creeping plants with upright tips
Attribution
Fact sheet prepared by Marley Ford (22 April 2023). Information in the Brief description, Distribution, Habitat, Features and Similar taxa sections copied from Galloway (1985, 2007).
References and further reading
Galloway D.J. 1985: Flora of New Zealand: Lichens. Wellington: PD Hasselberg, Government Printer. 662 pp.
Galloway D.J. 2007: Flora of New Zealand: Lichens, including lichen-forming and lichenicolous fungi. 2nd edition. Lincoln, Manaaki Whenua Press. 2261 pp.