Placopsis gelida
Common name
Bulls eye lichen
Synonyms
Lichen gelidus
Family
Trapeliaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Placodioid
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by neat, thalline rosettes; large central, deeply plicate cephalodia without pruina; eroding soralia generally delimited by a sharply defined and slightly raised margin, either scattered and discrete to confluent and covering much of the thallus; farinose greenish to green-grey soredia; and rather rare, scattered apothecia.
Distribution
South Island: Otago (Flagstaff, Mt Cargill, Mt Teviot, Blue Mountains), Southland (Stirling Point, Bluff).
Bipolar. Known also from both Northern and Southern Hemispheres where it has a wide distribution, being recorded from Great Britain and Ireland, Scandinavia, Iceland, Greenland, Europe, Macaronesia, North America, Siberia, and Java. Also recorded from Hawai’i and Australia. In South America it is known from Venezuela, Bolivia, and from the far south of Chile and Argentina.
Habitat
On rock outcrops from s.l. to 1000 m.
Detailed description
Thallus determinate, effigurate, ± lobate at margins, orbicular at first becoming confluent, spreading in a crust, to 8 cm diam., saxicolous, very rarely muscicolous. Marginal lobes closely to ± loosely attached, contiguous, separated by cracks to 0.1 mm wide, 1.5-2.5 mm long or extending to centre of thallus, areolate-cracked centrally, apices uneven, rounded or crenulate, sometimes with a narrow, olive-brownish peripheral zone. Upper surface ± areolate-cracked, areolae irregularly angular, ± swollen or plane, 0.6-2 mm diam., glaucous, whitish, creamish or olive brownish, smooth, matt, epruinose, sorediate. Soredia scattered, central, rounded or radially elongate, eroded or plane, often irregularly confluent, granular, olive-greenish or whitish. Isidia absent. Cephalodia discrete, central in young thalli, scattered in older plants, sessile, 1-3(-8) mm diam., orbicular, radially folded and cracked, yellow-brownish to red-brown, matt. Apothecia rare, scattered, sessile, orbicular, 0.8-2 mm diam., thalline margin thick, prominent, entire, matt, proper margin occasionally visible, thin, entire, pinkish-red or brown, disc plane, smooth or minutely scabrid, dark pinkish to yellow-brown or red-brown, often white-pruinose, matt. Hymenium 110-200 µm tall, pale sordid yellowish or granular-nubilated in upper part. Hypothecium colourless or faint pinkish. Ascospores uniseriate or subbiseriate, ellipsoid, 12-20 × 6-13 µm. Pycnidia immersed in slight swellings, ostioles brown-black, 0.1 mm diam. Conidia filiform, straight or curved, 15-27 × 0.5 µm.
Chemistry: Thallus K−, C+ red, KC+ red, Pd−; containing gyrophoric acid.
Substrate
Saxicolous
Attribution
Fact sheet prepared by Melissa Hutchison (16 June 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.
Galloway D.J. 2013: The lichen genera Aspiciliopsis, and Placopsis (Trapeliales: Trapeliaceae: Ascomycota) in New Zealand. First published by Magnolia Press, in Auckland. Phytotaxa 120(1): 1-194.