Usnea inermis
Family
Parmeliaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Fruticose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by the corticolous habit; the tufted to somewhat elongate, yellow-green thallus that may sometimes have black banding or even be completely superficially blackened; irregularly to densely branched; terete to angular-compressed branches, 1–1.5 mm wide at base, with long secondary branchlets parallel to primary branches; soralia are sparse to frequent with isidiomorphs. Soralia become eroded-pulverulent when the isidiomorphs fall off or break down to soredia. Isidiomorphs can be black tipped. There are three chemotypes: psoromic acid, squamatic acid or nil acids. All of these will give a K negative spot test.
Distribution
North Island: Northland (Warawara Range, Kawerua, Bay of Islands, Aorangi Island, Hen & Chickens Island, Great Barrier Island, Little Barrier Island), Auckland (Auckland City), South Auckland (Mt Maungatawhiri Coromandel Peninsula, Great Mercury Island, Slipper Island, Whale Island, Rotorua, Hamilton), Wellington (Kapiti Island, Mokopuna Island). South Island: Marlborough (d’Urville Island), Canterbury (Riccarton Bush, Prices Valley, Mt Sinclair Banks Peninsula), Otago (Omarama, Shag Valley, Waikouaiti River, Flagstaff, Wairongoa, Waipori, Maungatua), Southland (the Wilderness, Borland Bog). Stewert Island: (Islet Cove, Port Pegasus).
Known also from Australia.
Habitat
Coastal and lowland to subalpine on scrub. On trees and shrubs in coastal forest; frequent on introduced trees and shrubs and on decorticated wood (fenceposts, gates etc.).
Detailed description
Thallus glossy, smooth, branching rather irregular, corticolous. Branches 1-1.5 mm wide at base, tapering towards apices, terete or irregularly subterete, to angular-compressed, slightly faveolate- impressed in parts, Branches are tapering and often forked at the apex, these may be blacktipped. Occasionally papillate. Soralia sparse to frequent, flat, becoming subconvex and, later eroded- pulverulent, rarely completely investing branches in spreading, convex soralia. Apothecia not seen.
Chemistry: There are three chemotypes, psoromic acid, squamatic acid or nil acids. All three give a K negative spot test result, however the psoromic acid chemotype gives a bright yellow result with P.
Similar taxa
Subalpine collections from Discaria and Melicytus alpinus are often superficially blackened and strongly resemble species of sect. Neuropogon. Yellow/green forms of U. inermis can be confused with Usnea torulosa. The lack of norstictic acid can distinguish U. inermis from U. acromelana.
Could also be confused with U. cornuta and U. dasaea, but U. inermis can be distinguished from the other species chemically because it is never K+. Usnea cornuta and U. dasaea are both K+ but U. dasaea will slowly turn a deep dark red because of the galbinic acid. Also the axis is very narrow in U. cornuta, with a lax medulla.
Substrate
Corticolous, lignicolous.
Etymology
inermis: Not spiny, unarmed
Attribution
Fact sheet prepared by Marley Ford (2 May 2021). Brief description, Distribution, Habitat, Features, and Similar taxa sections copied from Galloway (1985, 2007), with suggestions from Dr Jennifer Bannister.
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.