Varicellaria cacuminum
Synonyms
Pertusaria montana Imshaug
Family
Pertusariaceae
Flora category
Lichen – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Lichens - Crustose
Current conservation status
Not Evaluated
Brief description
Separated from other species of the genus by its saxicolous habit, lack of soralia and abundant apothecia with single-spored asci containing enormous, single-celled ascospores.
Distribution
Known only from rocks on the summits of several mountains on Campbell Island, New Zealand.
Habitat
On rocks on the mountain tops of Campbell Island. Associated lichen species in the collections are few but include Megalaria obludens, Miriquidica effigurata, and small, indeterminate thalli of Placopsis sp. and Trapelia sp.
Detailed description
Thallus creamy white, becoming pinkish in the herbarium; widespreading, several centimetres across, with a well-defined margin, sometimes with a thin indistinct greyish prothallus; areolate-rimose, areoles usually ± flat, sometimes irregularly slightly convex, rhomboid with irregular margins, (0.4–)0.6–0.8(–1.2) mm across, 0.4– 0.7 mm thick. In Section: cortical zone 25–50 µm thick, brown at the surface becoming paler lower down; photobiont zone c 100 µm thick, interrupted by bundles of medullary tissue; photobiont chlorococcoid, cells 9–15 µm diam.; medulla c. 500 µm thick, IKI–. Apothecia scattered to locally abundant in groups 1–2 cm across, arising from thalline warts 0.4–0.6 mm diam., initially ± poriform but expanding to expose a slightly concave, white granular pruinose disc up to 0.4 mm across with a thick, raised thalline margin c. 0.1 mm thick. In Section: hymenium 250–350 mm high, IKI+ orange-brown, but IKI– after pre-treatment with K, paraphyses abundant, branched and anastomosing c. 1.5 µm wide, upper part of hymenium and exciple usually dark brown (K+ golden brown) pigmented. Exciple composed of several layers of cells c 5 µm wide. Asci ± completely filled by the ascospores except for a small conical space at the apex, no features distinguishable, IKI+ dark blue after pre-treatment with K; ascospores 1/ascus, (178–)241.7 ± 32.9(–315) × (50–)86.8 ± 16.58(–112) µm, l/b ratio (2.0–)2.88 ± 0.57(– 4.2), n = 25, wall 10–12 µm thick, with a thick stratified outer layer c. 10 µm thick and thin inner layer 1–2 µm thick, surface smooth with a thick gelatinous epispore. Conidiomata rare, immersed in the thallus with only a pale ostiole visible, conidia bacilliform 4–6 µm long
Chemistry: K–, C+ red, Pd–, UV+ bright pale creamy-yellow; lecanoric acid detected by tlc and GE microcrystal test, ±unidentified substance, ±atranorin.
Similar taxa
The only other species of Varicellaria currently reported from New Zealand is V. velata (Turner). This species is similar to V. cacuminum in having large ascospores in mono-spored asci, but differs, primarily, in its corticolous habit. It occasionally occurs on rock when it can be distinguished from the new species by its apothecia having a fully exposed disc at maturity that is usually coated with farinose pruina giving the impression of a thallus covered with punctiform soralia. The two species also differ chemically having very different reactions under UV light. Whereas V. velata only fluoresces dull orange-brown, the new species fluoresces bright pale creamy-yellow, although the substance responsible for this reaction is unknown.
Other species in the New Zealand lichen biota can be distinguished from V. cacuminum by thalline chemistry and ascospore dimension. Pertusaria otagoana D.J. Galloway is the only species with similar sized ascospores but that species differs in having poriform apothecia enclosed in raised thalline warts with a dark ostiole, and a thallus containing norstictic acid.
Substrate
Saxicolous
Etymology
cacuminum: cacumen = summit (genitive plural cacuminum = of the summits)
Dr Henry A. Imshaug had annotated the collections Pertusaria montana, but this name has subsequently been used for a very different species from China
Attribution
Fact sheet prepared by Marley Ford (3 October 2022). Brief description, Distribution, Habitat, and Features sections copied from Fryday (2022).
References and further reading
Fryday A.M. 2022: Varicellaria cacuminum (lichenized Ascomycota, Pertusariales), a new species of lichenized-fungi from Campbell Island/Motu Ihupuku, with notes on Varicellaria and other Pertusariales in New Zealand. New Zealand Journal of Botany 60. https://www.tandfonline.com/doi/full/10.1080/0028825X.2022.2120823