This is a macrolichen that is recognizeable also for non-specialists.
Morphology: Thallus corticolous or ± muscicolous, wide-spreading, in +/- loosely attached patches to 10 cm diam, on mossy boles or encircling smaller branches and twigs, grey in shade or more often suffused or entirely deep
red-brown in exposed habitats; lobes numerous, overlapping, +/-horizontal to 1 cm long and 0-6 cm wide. Upper surface with a +/-complete or incomplete, coarse, raised white sulcate reticulum with a finer pale mosaic within (faintly
seen in the dry state becoming very distinct in moist thalli). The coarse sulcate reticulum sometimes cracks but soredia or isidia do not develop, instead sulcae give rise to few or numerous folioles which are simple, nodulose or flattened,
rounded, becoming variously lobed with a distinct paler margin, sometimes so abundant as to obscure the main lobes of the thallus. Margins at first +/- even and entire, undulate, often becoming crenulate-uneven or with few to numerous, often clustered, simple or branched folioles. Lower surface mostly pale tan, only brownish medially, smooth or often faintly striate-ridged, generally even or in part +/- shallowly bullate, naked or sparingly pale pubescent. Medulla white. Photobiont Nostoc. Apothecia rather scarce, persistently concave with a +/- raised margin around the disc, about 1-5 mm from the lobe apex, lobe margins often frilled, sometimes proliferating disc red-brown, shining, dorsal surface patchily sulcate-ridged, not scabrose. Pycnidia not observed.
Anatomy:Thallus 110-140 (-180) μm thick. Upper cortex 22-25 μm thick, even, fractured in vicinity of sulcae, 4-5 cells thick, colourless to pale red-brown, lumens up to 7 μm diam, rounded, covered by a thin gelatinized layer at the surface. Lower cortex 11-15 μm thick, 2-3 cells thick, colourless, cell lumens up to 5 μm diam, walls rather unequally thickened, hairs sparse, mostly concentrated in the median area of older parts of lobes, simple, 1-4 celled, up to
25 μm in length, colourless, cells 2-4 μm, +/- spherical or cuboid. Cortex above apothecia up to 7 cells thick, cells somewhat vertically elongate, 8-12 x 4-4.5 μm, pale straw above, colourless below. Photobiont layer c. 45 μm
thick, Nostoc, cells grey-blue or deep blue-aeruginose, 9-11 μm diam. Medulla 45 μm thick (to 180 μm in the vicinity of the sulcations), hyphae interwoven, 4-5 μm thick. Thecium (45-) 55-70 μm high, epithecium red-brown coagulating, paraphyses simple, rather stout widening to 5-7 μm at the apices,
hypothecium 20-25 μm, pale red-brown, asci 40-55 x 17-20 um. Ascospores pale brown, eventually becoming red-brown, ellipsoidal, three-septate, (16-)17-20 x 6.4-7 (-8) μm.
This is macrolichen belonging to a taxonomically well known group. It is restricted to native forest remnants on one or two islands of the Azores, where it is rare.
A criterion: lack of information prevents application of A.
B criterion: does not apply as population is not documented to be highly fragmented.
C criterion does not apply.
D criterion: estimated number of occupied trees >125 but <500, the species would qualify as VU under D1.
The species is proposed as VU under D1.
Azores, known with certainty from Pico, between 500 and 900 m alt.
EOO = 31.5 km sq
AOO = 21 localities times 4 = 84 sq. km, which is higher than the EOO, so AOO = also 31.5
Epiphytic in the remnants of natural mountain forest on Pico, where it probably occurs only with several square meters, and at most a few square decameters.
In historical times also found on Terceira, where it has not been seen for about a century now, despite increased research, so that it can be safely reported as extinct on Terceira. There are also reports from Faial and Sao Miguel. These need to be confirmed.
The species is so rare that no picture is available on internet.
It would probably be correct to say that out of four known localities one is extinct, depending on the definition of locality (i.e. when areas with different names are seen as different localities, not if this is defined as 1 km2). This would mean that decline is 25% (based on the number of localities). For detailed quantitative information on Pico, see the distribution map in the illustrations part.
Population Trend: Decreasing
Epiphytic on native trees in remnants of natural mountain forest.
Indirect: Climate change may cause the microclimate to become unsuitable.
Indirect: Invasive plants may similarly change the microclimate of these relatively open, low forests.
Direct: Developments for tourists, like parking places, new roads and lodges.
A summary of threats to Madeira laurisilva forests can be found from the WWF: http://www.worldwildlife.org/ecoregions/pa0425
Preserving the forest remnants in their original species composition. Zero tolerance for invasive trees, shrubs and larger herbaceous plants.
Recent reports from other areas than Pico should be checked for accuracy.
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.