Sclerophyton rostratum Egea & Torrente

Data Set Maintenance: Data set authentic and standard item. Data set author(s): Egea J. M. & Torrente P. (00.03.23). Data set not to be published after submission.

Nomenclature: Current taxonomic status: basionymous or accepted. Taxonomic rank: species. Sclerophyton. Genus of unknown placement (incertae sedis) (Roccellaceae Chevall 1826); Arthoniales.

Taxonomic Literature: Egea J.M. & Torrente P., The Briologist 98: 207-217 (1995).

Biogeography: Continent: Northern America. Checklist records: Sonoran Desert.

Ecology: Biotroph; lichenized, lignicolous, episubstratic; growing partially shaded or fully shaded, under conditions which are dry.

Lichen Photobionts: Primary photobiont present, trentepohlioid.

Thallus: Crustose, rimose or areolate (primarily areolate); separate thallus parts thick. Thallus Outline: Often persistent. Upper Surface: Grey-green or brownish yellow, smooth or rough; special structures absent; epruinose; without hairs; not sorediate, soralia isolated, not confluent with other soralia.

Reproduction Strategy: With sexual (and possible asexual) stages. Ascocarps: Perithecioid, orbicular or irregular, forming independently from the host thallus or mycelium, not emerging, becoming adnate, abundant, pseudostromatic, .2-.5 mm in diam.. Margin: Sometimes distinct to indistinct; external filaments absent. Disk: Plane, black, pruinose, pruina white. Exciple: Not carbonized, brownish red (above) to pale brown. Amphithecium (thalline excipulum): Photobiont absent. Amphithecial Cortex: Absent. Epithecium: Without epithecium; apical cells not swollen to slightly swollen. Hymenium: 300-350 µm high, white, iodine reaction: Lugol’s negative, hemiamyloid. Interascal Hyphae: Present, distinctly branched, distinctly anastomosed; cells 1.5 µm wide. Hypothecium: Pale brown, pigment not homogenously distributed.

Asci: Narrowly clavate, indistinctly stipitate, 100-120 µm long, 20-23 µm wide; tholus thickened, amyloid, hemiamyloid, in Lugol's Solution + dark blue, with amyloid tube; dehiscence bitunicate; endoascus hemiamyloid throughout.

Ascospores: c. 8 per ascus, fusiform, 30-42-(45) µm long, 6-8 µm wide; septa present, 5-7-transversally septate; lumina apically enlarged, constricted at the centre; wall thick, distinctly differentiated into primary and secondary wall, laterally constricted where the septum meets the spore wall, becoming pigmented, middle brown to hyaline, not ornamented, distinctly halonate, i.e., with a thick mucilaginous sheath.

Conidiomata: Present, pycnidial.

Pycnidia: Subglobular. Conidia: Filiform to curved; microconidial, 14-18 µm long, 1 µm wide; aseptate.

Secondary Metabolites: Present, 2'-O-demethylpsoromic acid to psoromic acid.

Spot Tests: Present reactions. Upper surface: K – (negative) to + deep yellow, KC –, PD + orange.

(report generated 04.Okt.2007)