This is a macrolichen that is well recognizeable, also to non-specialists.
Morphology: Thallus corticolous or partly muscicolous, to 6 cm diam, or
more often of dispersed lobes or fragmentary over mosses, light grey becoming ± suffused red-brown, lobes rather narrow, 0.3-10 cm broad, fragile, thin, papyraceous, mostly closely adpressed, often ± elongate, ± imbricate at the centre. Upper surface smooth, undulate, rarely subfaveolate in part, ± shining
or faintly reticulate but without well-defined sulcae, lacking isidia and soredia, but sometimes with scattered or rarely clustered adpressed folioles. Margins
irregular, often downturned, generally with scattered or +/- clustered, crenulate folioles. Lower surface ± smooth, occasionally striate-ridged, persistently
naked, pale buff, becoming darker brown towards the median part of older lobes. Medulla white. Photobiont Nostoc. Apothecia frequent, disc rounded to
reniform, red-brown to black, margins +/- entire or irregularly crenulate, +/- incurved edges or ill-formed folioles, dorsal surface smooth, not areolatecracked,
+ subfaveolate. Pycnidia not uncommon, marginal, semi-immersed, pale red-brown.
Anatomy: Thallus c. 230 μm thick. Upper cortex 25-28 μm thick, 2-4 cells thick, colourless, lumens 5-10 μm diam, overlain by a colourless amorphous layer 2-4 μm thick. Lower cortex pale, c. 10-20 μm thick, lumens c. 4 μm diam,
septate hairs absent. Cortex above apothecia smooth at outer edge, 25-45 μm, 3-5 (-7) cells thick, colourless, overlain by a colourless featureless layer, 6-9 μm thick. Photobiont layer 50-65 μm thick. Nostoc cells violet-blue. Medulla
90-100 μm thick, very compacted, hyphae unorientated, c. 4 μm thick. Thecium 80-85 μm high, +/- pale red-brown, hypothecium c. 35 μm, small-celled, compact, pale red-brown, paraphyses simple, c. 4 μm thick, enlarging towards the
apices to c. 6 μm, epithecium red-brown. Ascospores pale to red-brown, 3-septate, (13-) 15-19.5 (-21) x 6-7 (-7.5) μm. Conidia longly ellipsoid with tapered ends, 3-4 x 1 μm, smaller than usual for the genus.
This is a macrolichen species belonging to a taxonomically well known group, occurring in the sparse native forest remnants on an island with growing tourism. It is susceptible to changes in microclimate, e.g. caused by developments for tourism in adjacent areas.
A criterion: will not be applied, owing to lack of concrete data.
B criterion: will not be applied, owing to lack of concrete data.
C criterion does not apply.
D criterion: species can be considered under criterion D to be VU owing to number of occupied trees <500.
The species is proposed for listing as VU (D1) owing to a small overall number of colonized trees.
Madeira; an unlocalized single old report from the Canary Islands, mentioned in the original publication, is apparently wrong and a result of incorrect labeling.
Only occurring on trees in the natural mountain forest remnants around 850 m on Madeira. Total Area of Occupancy probably only a few square meters, at most a few square decameters (pers. obs. F. Schumm, A. Aptroot & others).
Population Trend: Uncertain
Epiphytic on trees in the remnants of natural mountain forest on Madeira. This habitat, known as laurisilva, is endemic to Macaronesia and has suffered much losses in the past century.
Direct: Forest descruction, road expansion, forest fire andf collecting by lichenologists and naturalists.
Indirect; This species is dependent on a humid microclimate in native forest remnants. Both the global warming and the development of areas lower on the island for tourism have had a drying effect already in recent decades.
A summary of threats to Madeira laurisilva forests can be found from the WWF: http://www.worldwildlife.org/ecoregions/pa0425
Limit developments for tourism in areas adjacent to native forest. The species should not be collected anymore, and should feature on a leaflet with protected plants.
James, P.W. and White, F.J. 1987 Studies on the genus Nephroma I. The European and Macaronesian species. Lichenologist 19: 215-268.
Sérusiaux, E. 1989 Liste Rouge des macrolichen dans la Communauté Europeenne. Département de Botanique, Liège.