Placopsis perrugosa
Common name
Snakeskin lichen
Synonyms
Lecanora (Eulecanora) endorhodea, Lecanora perrugosa, Placodium perrugosum, Placodium thaumastum, Squamaria perrugosa, Squamaria thaumasta
Family
Trapeliaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Foliose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by closely appressed thalli forming neat rosettes to irregularly spreading and coalescing patches 1–10 cm diam., occasionally more; expanded, 2–5(–8) mm long and 1.5 mm wide, irregularly branched, rounded to somewhat cuneate at apices; an upper surface that is variable in colour, creamish, grey-green or grey-white, olive-brown, grey-brown to dark red-brown or brown-black, distinctively shallowly verrucose-papillate resembling snakeskin, especially towards margins, cracked, with cracks 0.2–0.3 mm wide separating angular areolae to 1.2 mm diam., centrally verruculose-areolate, verruculae crowded, hemispherical. to 0.5 mm diam., glossy rarely finely white-pruinose in parts, without isidia, or soredia; cephalodia that are scattered, sessile, flattened, suborbicular to 2.5 mm diam., or effigurate, radially cracked to 3 mm diam. or coalescing centrally to 5 mm diam., to warted-glomerulate and not effigurate to 3.5 mm diam, yellowish to red-brown, matt, not pruinose, containing Nostoc or Scytonema; apothecia that are scattered, to crowded, sessile to subpedicellate, rounded 0.5–1.5 mm diam.; with a thalline margin that is prominent, persistent, entire, smooth to glossy; discs that are plane, pink- or red-brown to dark-brown to ±black, matt, epruinose; an epithecium that is yellow-brown, and 15–20 μm thick; a colourless hymenium, 100–200 μm tall; ellipsoidal ascospores (13–)15–18(–21.5) × 7–9(–9.5) μm; pycnidia immersed in thalline verrucae, ostioles punctiform, brown-black; and conidia that are thread-like, straight or curved, 18–24 × 0.5 μm. P. perrugosa is often parasitised by *Phaeospora perrugosaria (q.v.).
Distribution
North Island: Northland (Warawara Ranges, Kawerua, Mt Tutamoe, Great Barrier Island), Auckland (Rangitoto Island, Takapuna), South Auckland (Coromandel Peninsula, Te Aroha), Hawke’s Bay (Puketitiri), Wellington (Mt Ruapehu, Ohakune, Ruahine Ranges, Tararua Ranges). South Island: Nelson (Mt Arthur, St Arnaud Range), Westland (Buller River, Kelly’s Creek, Fox Glacier, Haast River), Marlborough (d’Urville Island, Ship Cove, Mt Fyffe), Canterbury (Arthur’s Pass, Waimakariri River, Cass, Craigieburn Ranges, Torlesse Ranges, Akaroa Banks Peninsula, Upper Godley Valley, Kea Point Mt Cook, Waihi Gorge, Lake Ohau), Otago (Huxley River, Makarora, Earnslaw Burn, Forgotten River, Mt Watkin, Harbour Cone Otago Peninsula, Swampy Hill, Maungatua, Taieri Mouth), Southland (Homer, Wapiti River, Spey River, Borland Saddle, Invercargill). Stewart Island: (Oban Cemetery). Chatham Islands: (Te Awatapu slump). Auckland Islands: (Laurie Harbour). Campbell Island: (Mt Lyall, Mt Dumas, Tucker Cove, Mt Fizeau, Mt Sorenson, Mt Honey).
Known also from Australia, Papua New Guinea, the Galapagos Islands, southern South America, the Falkland Islands and Tristan da Cunha.
Habitat
A widespread and often common species (the most commonly encountered species in New Zealand) spreading over rock faces, boulders, stones and pebbles, along river and stream banks, glacial moraines and roadside cuttings where native rock is exposed; rarely on decorticated wood impregnated with sand, occasionally on old rusty iron and commonly (though locally) on polished surfaces of tombstones in cemeteries, and locally common on margins of bitumen footpaths and roads, s.l. to 2000 m.
Detailed description
Chemistry: Gyrophoric acid (major) and lecanoric acid (minor).
Similar taxa
Placopsis perrugosa has marginal lobes that are discrete, often furcate or divergent, and flattened, not swollen, contiguous and ±inrolled as in P. brevilobata (q.v.).
Substrate
Saxicolous, occasionally lignicolous, or on artificial surfaces (bitumen, iron)
Attribution
Fact sheet prepared by Melissa Hutchison (February 2023). Brief description, Distribution, Habitat, and Features 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.