Buellia epigaea (Pers.) Tuck. Gen. lich.: 185 (1872)

Fig. 7

Type.

Germany. Hesse, ad terram inter muscos non procul a Monte Meissner, 1794, Persoon (H-Ach-Isotype, not seen) .

Description.

Thallus terricolous, tightly attached to the substrate, upper surface white or greyish white, usually with white fine pruina, thallus crusty, uneven to wrinkled, 0.2-1 mm thick, prothallus absent; the upper cortex 60-150 µm thick, with granular crystals, pith completely interspersed with Ca oxalate crystals; medulla white. Apothecia sparse to dense, lecideine, but usually surrounded by a thalline collar (pseudolecanorine); disc black, always with finely white pruina, roundish, 0.5-1.0 mm in diam., mostly flat, rarely slightly convex; young apothecia immersed and margin with finely white pruina breaking out broadly, mature apothecia adnate and margin absent or not obvious; exciple Buellia aethalea -type, up to 50 µm thick, without aeruginose pigments (HNO3-); epihymenium brown to dark brown; hymenium hyaline, 60-80 µm tall, without oil droplets, paraphyses simple to moderately branched, apically swollen, with a brown pigment cap; hypothecium hyaline to light brown, up to 100 µm high; asci oval-clavate, Bacidia -type, eight-spored; spores 1-septate, hyaline when young, turning brown when mature, with tapering ends, Callispora -type, often curved, not thickening during spore ontogeny, 12-20 × 6-10 µm . Pycnidia not seen.

Chemistry.

Thallus K-, C-, KC-, PD-, UV-; without secondary metabolites.

Distribution and ecology.

This species mainly occurs on open and dry soil, soil within meadows or on soil over rock, between elevations of 2300-4700 m. This species has been recorded in Asia, Europe and North America (Trinkaus and Mayrhofer 2000). In China, it is mainly distributed in Gansu, Qinghai and Xizang Provinces.

Note.

The species is a new record for China; it could be distinguished from all the other terricolous Buellia species reported in China by the combination of the following characteristics: thallus white crustose, uneven to wrinkled, always covered by finely white pruina, apothecia pseudolecanorine, the ornamentation of the ascospore surface densely areolate and rough, pycnidia rare, Callispora -type ascospores and absence of secondary metabolites. This species is close to Tetramelas species in phylogeny and similar in morphology, but could be distinguished by absence of the secondary metabolites 6-O-methylarthothelin or related xanthones, and pseudolecanorine apothecia covered with white pruina.

Selected specimens examined.

China. Gansu Prov.: Sunan Co., along the route from Linze to Sunan, on soil over rock, 38°52'26"N, 99°44'21"E, alt. 2294 m, 29 May 2018, L.S. Wang et al. 18-58766; Sunan Co., along the route from Linze to Sunan, on soil over rock, 38°52'47"N, 99°43'57"E, alt. 2296 m, 29 May 2018, L.S. Wang et al. 18-59699 . Qinghai Prov.: Gonghe Co., meadow beside Qinghai Lake, on soil within meadow, 36°33'26"N, 100°28'45"E, alt. 3431 m, 18 May 2018, L.S. Wang et al. 18-59162 . Xizang Prov.: Qushui Co., Niedang Vil., on soil, 29°30'24"N, 90°56'17"E, alt. 3527 m, 22 Jul. 2019, X.Y. Wang et al. XY19-1234; Qushui Co., Niedang Vil., on soil over rock, 29°30'22"N, 90°56'15"E, alt. 3624 m, 22 Jul. 2019, X.Y. Wang et al. XY19-1218; Langkazi Co., entrance to Karuola Glacier, on soil over rock, 28°53'54"N, 90°13'32"E, alt. 4774 m, 24 Jul. 2019, X.Y. Wang et al. XY19-2294 .