Placocarpus melanophthalmosus Cl. Roux & Gueidan
Bull. Soc. linn. Provence, num. spéc. 14: 165, 2011
Synonyms:
Distribution:
Description: Thallus at first crustose, then squamulose, developing on the thalli of Rhizoplaca-species, the squamules of very variable sizes, 0.5-20 x 0.2-13 mm, 0.2-3 mm thick, brown but completely ash-grey-pruinose, subdivided into smaller, convex elements. Upper cortex composed of 1–2(-4) layers of para- or almost scleroplectenchymatous cells in the upper part, and a colourless lower part, overlain by a 2.5-15 μm thick epinecral layer (sometimes missing); small crystals (insoluble in N, soluble in K) present in upper cortex and algal layer, visible under polarized light; medulla thick, white, I + slowly (and often faintly) blue, with both large and small crystals. Perithecia without involucrellum, immersed in the squamules, up to 50 per squamule, appearing as black dots. Exciple pyriform, colourless throughout, except near the ostiole; hamathecium of short periphyses and pseudoparaphyses, interascal filaments absent; hymenial gel hemiamyloid, I+ red (I+ blue at very low concentrations of I), K/I+ blue. Asci 8-spored, clavate, bitunicate, with a thick tholus and an ocular chamber, I- except the outer coat which reacts I+ reddish, 61-72 x 18.5-23 μm. Ascospores 1-celled, hyaline, long-ellipsoid, (15.5)18.3-25(-27) x (6-)8-10(-12) μm, thinly halonate especially when young. Pycnidia immersed, appearing as black dots as the perithecia, pyriform to subglobose, plurilocular, Dermatocaarpon-type. Conidia simple, hyaline, short-bacilliform, straight, (3.5)4-5.5(-6) x 1-1.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.Note: a species first described from the Pyrenees as a parasite of Rhizoplaca melanophthalma, later also found in the French Alps (Alpes-de-Haute-Provence) as a parasite of Rhizoplaca chrysoleuca (Roux & Gueidan 2011, Roux & Bertrand 2016). To be looked for in the Italian Alps.
Growth form: Squamulose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)
paras Rhizoplaca-species
Predictive model
M. Bertrand - Source: Roux C. & Bertrand M. (2016) Bull. Ass. Fr. Lichénologie 41(1): 1-7 Placocarpus melanophthalmosus Cl. Roux et C. Gueidan: nouvelle station, nouvel hôte.
France
Growth form: Squamulose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)
paras Rhizoplaca-species
Predictive model
