Heterodermia tremulans
Family
Physciaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Foliose
Current conservation status
2018 | At Risk – Naturally Uncommon | Qualifiers: DP, SO
Distribution
Only recently recognised to be present in New Zealand so distribution is poorly known. Current records are from Northland and the Farewell Spit area.
Also in Australia. A pantropical and pantemperate lichen.
Habitat
Coastal rock
Detailed description
Thallus foliose, orbicular to irregularly spreading, adnate to loosely adnate, 2–7 cm wide, often coalescing and forming colonies to 15 cm wide. Lobes 0.7–1.5 mm wide, plane to slightly convex, sublinear, ±flexuose, dichotomously to subdigitately branched, usually discrete at the periphery, radiating; apices not ascending, with short lateral lobes, eciliate. Upper surface greyish white to grey to brownish grey, ±darker at the apices, pruinose or not, sorediate; soredia whitish or greyish, granular, forming labriform soralia at the tips of the main and lateral lobes. Medulla white. Lower surface corticate, whitish to pale brown, rarely dark grey in the centre. Rhizines sparse, marginal, concolorous with the thallus or becoming darker, or even black near the apices, irregularly branched, to 1 mm long. Apothecia rare, laminal, sessile to substipitate, 1–3 mm wide; margin initially crenulate, becoming sorediate; disc concave, brown to brown-black, epruinose. Ascospores Pachysporaria-type, ellipsoidal, 23–32 × 12–14 μm. Pycnidia immersed or slightly protruding; conidia bacilliform, 4–5 × 1 μm.
Chemistry: Cortex K+ yellow, C–, KC–, P+ yellow; medulla K+ yellow, C–, P– or P+ pale yellow; containing atranorin (major), zeorin (major), 16β-acetoxyhopane-6α,22-diol (major), 6α-acetoxyhopane-16β,22-diol (major), 6α,16β-diacetoxyhopane-22-ol (minor), leucotylin (minor), chloroatranorin (minor).
Similar taxa
Although this lichen has commonly been confused with Heterodermia speciosa, the latter has linear-elongate lobes and larger spores (25–37 × 14–18 μm), whereas H. tremulans has short, often flexuose lobes and smaller spores (23–32 × 12–14 μm).
Substrate
Saxicolous (coastal rock)
Etymology
heterodermia: From the Greek heteros (other, different) and derma (a skin or hide), in reference to the presence or absence of a lower cortex
tremulans: trembling, shaking
Attribution
Fact sheet prepared by Marley Ford (3 March 2021). Brief description, Distribution, Habitat and Features sections copied from Elix (2011).
References and further reading
Elix J.A. 2011: Heterodermia. Australian Physciaceae (Lichenised Ascomycota). Australian Biological Resources Study, Canberra. Version 18 October 2011. http://www.anbg.gov.au/abrs/lichenlist/PHYSCIACEAE.html
Taylor M., Bieleski R.L. and Allan H.H. 2002: Meanings and origins of botanical names of New Zealand plants. Auckland Botanical Society Bulletin 26.