Placopsis murrayi
Family
Trapeliaceae
Flora category
Lichen – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Lichens - Placodioid
Current conservation status
2018 | At Risk – Naturally Uncommon | Qualifiers: RR
Brief description
Characterised by the thick, tartareous, closely attached thallus with neatly delimited, pleated margins; a white medulla suffused with a yellow pigment (K+ reddish purple) in the lower parts; conspicuous long, deep, parallel cracks radiating from centre to margins; characteristic immersed, elongated, vein-like cephalodia; immersed aspicilioid apothecia developing centrally; and broadly ellipsoidal to ovoid ascospores, (20–)23–27(–28.5) × 15–17.5 μm.
Distribution
North Island: Hawke’s Bay (Waipawa Saddle (Lat. 44ºS) on the Ruahine Range). South Island: Canterbury (Goat Pass at the head of the Mingha Valley near Arthur’s Pass (Allison Knight, pers. comm.)), mountains of Otago and Southland between lat 44º30’S and 45º16’S (e.g. Secretary Island, Head of Gorge Burn, S arm of Lake Te Anau, Dusky Sound, Mt Hodges).
Only rarely collected. More widely distributed in high-rainfall areas and is well worth looking for, as it is a most exciting lichen to see in the field.
Habitat
On hard rocks above treeline in high-rainfall areas close to, but especially west of, the Main Divide in Fiordland, south-western New Zealand. Here, it associates with Aspiciliopsis macrophthalma, Porina guentheri, Porpidia macrocarpa, Placopsis aspicilioides, P. lambii, P. subcribellans, and also with an unidentified, athalline species of Scolicosporum. Further north, in West Otago (Hidden Falls), P. murrayi co-occurs on damp, moss-covered rocks with Hypogymnia lugubris, Lichina minutissima, Mycobilimbia australis, Parasiphula fragilis, Placopsis subgelida, Siphula decumbens, and Stereocaulon colensoi.
The apparent rarity of P. murrayi, plus the difficulty in collecting specimens of it from extremely hard rock in remote parts of Fiordland, has meant that comparatively few specimens have so far been collected, and we do not as yet have a very good idea of its ecological requirements. It is not known from Stewart Island or from the subpolar islands to the south (Galloway 2004).
Detailed description
Thallus rosette-forming to irregularly spreading, or in coalescing patches, closely attached to substratum, 400–650(–800) μm thick, tartareous, (1–)2–5(–7) cm diam., without a marginal prothallus, but with a dark-brown to black prothalline zone underlying thallus and attaching to substratum, 150–250 μm thick, overlain by a pigmented, ochraceous zone, 50–100 (–250) μm thick, the pigment commonly visible as an ochraceous zone at base of cracks near centre of thallus, and reacting K+ reddish purple. Upper surface pale-pinkish or pinkish white when dry (pale lettuce-green when wet); uniform, smooth or shallowly undulate, minutely maculate through regular discontinuities in photobiont layer, small, isolated clumps of photobiont appearing as minute, green maculae (×10 lens) when wet; without isidia, pseudocyphellae or pruina; dissected by long, deep, parallel cracks radiating from centre to margins, cracks dividing margins into contiguous, flabellate lobes (1–)2–4(–6) mm wide. Margins entire, flat or shallowly convex, suffused brownish, abruptly and neatly delimited. Medulla white, with an ochraceous pigment (K+ reddish purple) in lower parts. Photobiont green, chlorococcoid, in dense clusters, cells rounded, 5–7 μm diam., in a discontinuous layer 140–150 μm thick. Cephalodia immersed, level with thallus surface, elongated, vein-like, never rosette-forming, 1–3 mm wide, 1–3 cm long, dividing into 2–3 branches towards periphery, radiating centrally and penetrating thallus to within 1 cm of margins, puplish blue when moist, pale pinkish white when dry, surface smooth or cracked, not pruinose; cyanobiont Scytonema, in chains, cells compressed, cylindrical to fabiform, 10–12.5 μm diam. Apothecia immersed, aspicilioid, developed on central areolae and delimited by narrow to deep cracks, solitary to 2–4-together, round to irregular or deformed through mutual pressure, 0.5–1.5(–2.5) mm diam., disc concave to plane, red-brown, covered with a thin to thick, pinkish or pale-brownish pruina. Thalline margin prominent, entire, smooth to minutely papillate, swollen, 0.2 mm thick, pale-pinkish. Proper margin very thin, visible as a pale-pinkish rim to disc, often separated from thalline margin by a narrow crack. Epithecium brownish, granular, 15–30 μm thick. Hymenium hyaline to pale yellowish brown, 150–200(–225) μm tall. Hypothecium opaque, densely interwoven, yellow-brown to dark red-brown. Asci cylindrical, 130–150 × (12–)15–20 μm. Ascospores uniseriate in ascus, broadly ellipsoidal to oval, apices rounded or pointed, (20–)23–27(–28.5) × 15–17.5 μm. Pycnidia widely scattered, immersed in thallus, 250–350 μm diam., ostiole punctiform-depressed, pale red-brown. Conidia not seen.
Chemistry: Thallus K− (above), K+ red-purple (lower medulla), C+ red, KC+ red, Pd−; containing gyrophoric acid (major), 5-O-methylhiascic acid (minor), lecanoric acid (minor), and two unidentified anthraquinones (minor) reacting K+ red-purple.
Similar taxa
It is distinguished from Aspiciliopsis macrophthalma by the elongated vein-like cephalodia, and the differing chemistry (Galloway 2013). The Campbell Island endemic, P. venosa, has smaller ascospores, narrower cephalodia, and a different chemistry (Galloway 2007).
Substrate
Saxicolous
Etymology
murrayi: This species was first collected by the late James Murray (1923–1961), in February 1959, from rocks in subalpine grassland above treeline on Secretary Island in Fiordland. Murray noted on his collection that the species was rare in this locality, and he recorded it as “Placopsis (Aspiciliopsis) new sp.” (Murray 1963a: 230). It is named in his honour.
The development of branched, elongated, vein-like, immersed cephalodia in the New Zealand species P. murrayi and P. venosa is a remarkable advance on the more usual, orbicular, flattened-effigurate to hemispherical type of cephalodia found in all other species (Galloway 2013).
Attribution
Fact sheet prepared by Melissa Hutchison (27 March 2022). Brief description, Distribution, Habitat, Features, and Similar taxa sections copied from Galloway (2007, 2013).
References and further reading
Galloway DJ. 2004. Placopsis hertelii (Agyriaceae, Ascomycota) endemic to New Zealand, with descriptions of four additional new species of Placopsis (Nyl.) Linds., from New Zealand. Bibliotheca Lichenologica 88: 147–161.
Galloway DJ. 2007. Flora of New Zealand Lichens. Revised 2nd edition including lichen-forming and lichenicolous fungi. In two volumes: vol. 1 pp 1–1006; vol. 2 pp 1007–2261). Manaaki Whenua Press, Lincoln, NZ. 2261 p.
Galloway DJ. 2013. The lichen genera Aspiciliopsis, and Placopsis (Trapeliales: Trapeliaceae: Ascomycota) in New Zealand. Phytotaxa 120(1): 1–194. https://doi.org/10.11646/phytotaxa.120.1.1.