Homostegia adusta Fuckel, Jb. nassau. Ver. Naturk. 23-24: 223 (1870)  Fig. 15

MycoBank number: MB 243056; Index Fungorum number: IF 243056; Facesoffungi number: FoF 06247;

Lichenicolous on thallus of Parmelia saxatilis. Sexual morph: Ascomata 660–780 µm high, 645–750 µm diam., immersed to semi-immersed, black, solitary, scattered, or in small groups, discoid to rounded, carbonaceous, multilocular, wall black to grayish, roughened, dehiscence via irregular slit appearing on upper part of the wall. Locules 94–143 µm × 98–107 µm ( x = 108.9 × 102.8 µm, n = 10), globose to subglobose, forming a single layer within ascostromata. Peridium 1– 2 layered, composed of reddish-brown pigmented cells of textura angularis. Hamathecium dense with cellular hyaline, septate pseudoparaphyses. Asci 34–37 µm × 14–17 µm ( x = 35.2 × 16.2 µm, n = 10), 8-spored, bitunicate, fissitunicate dehiscence not observed, obovoid to broadly cylindrical, forms short, broad, hamate shaped pedicel. Ascospores 16–22 × 6–9 µm ( x = 22.9 × 6.6 µm, n = 15), partially overlapping, fusiform to ellipsoidal to broadly ellipsoid, sometimes reniform, brown to reddish-brown with 3 longitudinal septa, constricted at septa, slightly curved, smooth-walled. Asexual morph: Undetermined.

Material examined –  GERMANY, Baden-Württemberg,  on thallus  of Parmelia  saxatilis (Parmeliaceae), 1869 -1870, KWG Fuckel (G-322312/1, holotype).

Economic significance – Species of Homostegia are lichenicolous fungi that are pathogens, saprotrophs, and commensals. The genus Homostegia has been reported to cause small yellow, indefinite spots on leaves of Bambusa sp. in the Philippines (Stevenson & John Albert 1926).

Figure 15 – Homostegia adusta (G-322312/1, holotype). a, b Details of herbarium material. c Habit and appearance of ascomata on host surface. d Locules within ascostromata. e Section of ascoma. f Peridium. g Hamathecium. h–j Asci. k–m Ascospores. Scale bars: c = 1 mm, d = 200 µm, e = 30 µm, f, h–j = 20 µm, g, k–m = 10 µm.