Arthonia radiata
Synonyms
Opegrapha radiata Pers., A. subramulosa Müll.Arg., Arthonia ramulosa C.Knight & Mitt.
Family
Arthoniaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Crustose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by the corticolous habit; the pale grey-white to brownish thallus, delimited by a thin black line of prothallus and forming mosaics on bark; black, elongate to branched apothecia in star-like clusters; and 3-septate ascospores, the apical cell not enlarged.
Distribution
North Island: Auckland, Wellington (Wellington City). South Island: Canterbury (Mt Palm, Lowry Peaks Range, Peel Forest).
Known from Great Britain, Europe, Scandinavia, North America and Australia.
Habitat
On smooth-barked trees (e.g. Acer pseudoplatanus*) in parks and gardens, and on Cytisus scoparius* and Discaria toumatou more widely in the countryside. A pioneer species on smooth bark of deciduous trees.
Detailed description
Thallus immersed, usually delimited by a brown or brown-black prothalline line and often mosaic-forming, whitish, pale-grey, sometimes with a brownish or olivaceous tinge. Apothecia variable, rounded, elongate to stellate, 0.2–0.8 mm diam., linear to sparingly branched or stellate and to 1–2 × 0.1–0.2 mm, flat to subconvex, black, epruinose. Hymenium 35–50 μm tall, colourless; epithecium brown or olivaceous, K+ greenish. Hypothecium 10–25 μm thick, colourless to pale olivaceous, K+ greenish. Paraphysoids numerous, 1–2 μm thick, apices slightly swollen to 3–4 μm diam., with brown apical caps. Asci broadly clavate. Ascospores obovoid to oblong, 3-septate, apical cell not enlarged, 15–20 × 4.5–6 μm.
Substrate
Corticolous
Attribution
Fact sheet prepared by Marley Ford (January 2023). Brief description, Distribution, Habitat, and Features sections sourced from Galloway (2007).
References and further reading
Galloway D.J. 2007: Flora of New Zealand: Lichens, including lichen-forming and lichenicolous fungi. 2nd edition. Lincoln, Manaaki Whenua Press. 2261 pp.