Immersaria Rambold & Pietschm., Bibliotheca Lichenologica 34: 239 (1989).

Xie, Cong-Miao, Wang, Li-Song, Zhao, Zun-Tian, Zhang, Yan-Yun, Wang, Xin-Yu & Zhang, Lu-Lu, 2022, Revision of Immersaria and a new lecanorine genus in Lecideaceae (lichenised Ascomycota, Lecanoromycetes), MycoKeys 87, pp. 99-132 : 99

Immersaria Rambold & Pietschm., Bibliotheca Lichenologica 34: 239 (1989).

Type species.

Immersaria athroocarpa (Ach.) Rambold & Pietschm., in Rambold, Biblioth. Lichenol. 34: 240 (1989).

Description.

Thallus crustose, yellow-brown, red-brown, orange-brown or brown, sometimes rust coloured, continuous; areolae irregular or tending to rectangular, with a glossy surface (atrobrunnea -type) caused by a layer of dead, colourless cells above the upper cortex, areolae sometimes aggregate with black prothallus and forming larger areolae; margin pruinose; prothallus distinct at the margin of thallus or absent. Upper cortex orange pigmented; epinecral layer colourless; algal layer continuous; medulla filled with grey granules. Apothecia lecideine, immersed, sometimes aggregate, round or irregular; disc black, flat, less concave, sometimes slightly raised, often poorly developed in section, pruinose or not; margin reduced. Exciple almost absent, sometimes developed, brown. Hymenium colourless; paraphyses simple, rarely branched, anastomosing or not; epihymenium brown, green or brown green, without plectenchyma; subhymenium colourless, sometimes pale brown; hypothecium pale brown to brown. Asci Porpidia -type, cylindrical, eight-spored; ascospores ellipsoid, halonate, non-amyloid. Conidiomata present or not, immersed, linear or stellate, black, margin pruinose; conidia bacilliform.

Chemistry.

Thallus K-, C-. Medulla I+ violet. Confluentic acid, often accompanied with 2'-O-methylmicophyllinic acid, planaic acid or no substances detected by TLC. The compound planaic acid is newly reported in this genus.

Ecology and distribution.

In China, growing on bare rock, sandstone or granite, from elevations of 3800 to 4500 m in the alpine zone of west China and elevations of 1200 to 1900 m in the steppe of north China. Worldwide distribution.

Notes.

Species with lecanorine apothecia were previously included in Immersaria ( Calatayud and Rambold 1998; Valadbeigi et al. 2011), but the five-loci phylogenetic analysis excluded these species from Immersaria. This exclusion entails a restricted concept of the genus. Immersaria is now defined by its orange-brown, yellow-brown, sometimes rusty coloured thallus, the amyloid medulla, the glossy surface of areolae with a pruinose margin, the black immersed lecideine apothecia with a reduced proper margin, the brown epihymenium and the Porpidia -type asci with eight halonate and non-amyloid ascospores. The members of this genus occur in alpine habitats.

Species of Sporastatia A. Massal. might be misidentified as members of Immersaria because of field observations of their glossy areolae and the immersed lecideine apothecia. However, they are characterised by multi-spored asci and their yellow-brown thallus. Additionally, Miriquidica Hertel & Rambold resembles Immersaria by its glossy areolae and the lecideine apothecia, but differs in its black brown thallus, its Lecanora -type asci with non-halonate ascospores and often containing miriquidic acid. The immersed apothecia of Immersaria may resemble Aspicilia A. Massal. and Acarospora A. Massal., but Aspicilia has a white or grey thallus, the Aspicilia -type asci with non-halonate ascospores; Acarospora has multi-spored asci.

Although four known species, Immersaria carbonoidea (J.W. Thomson) Esnault & Cl. Roux, I. fuliginosa Fryday, I. olivacea Calat. & Rambold and I. usbekica , currently lack molecular data, they are temporarily left in Immersaria due to their morphology which corresponds to that of Immersaria. Our morphological comparisons were based on high-resolution photographs of type materials and the original descriptions.