Microtheliopsis uleana Müll. Arg., Flora, Regensburg 73: 195 (1890), Figure 38

MycoBank number: MB 395632; Index Fungorum number: IF 395632; Facesoffungi number: FoF 04616;

Thallus crustose, continuous or dispersed into rounded to irregular patches, smooth or rarely thinly setose, ochraceous yellow to yellowish brown or green. Setae formed by single, unbranched, dark brown, septate hyphae. Photobiont cells rectangular, setose, pale zoosporangia and gametangia. Sexual morph: Ascomata 0.12–0.2 mm diam., perithecioid, scattered or aggregated, lens-shaped to conical, dark brown, smooth-walled, ostiolate. Ostiole indistinct. Excipulum 7–12 μm thick, paraplectenchymatous, inner part multi-layered, composed of narrow, thin-walled and periclinally elongate, almost hyaline cells, outermost part composed of irregular, thin-walled, dark brown cells. Involucrellum 5–10 μm thick, dark brown. Hamathecium lacking, gel I+ very faintly bluish, KI+ faintly bluish. Asci 18–34 × 6–9 μm (x̄ = 25 × 8 μm, n = 10), fissitunicate, broadly clavate to saccate, I-, KI- but lumen I+ yellow and KI+ pale yellow (colour of iodine itself). Ascospores 9–15 × 2–5 μm (x̄ = 12 × 3.6 μm, n = 10) 8-spored, overlapping 2-seriate, ellipsoid to fusiform, tapering towards both ends, pale to dark grayish brown, 3-septate, not constricted or slightly constricted at the septa, thin-walled, without gelatinous sheath. Asexual morph: Undetermined.

Material examined: Costa rica, Puntarenas Province, Reserva Biológica Carara, c.15 km SSW of Orotina, Alt. m. 50 m, 84° 37′ W, 9° 47′ N, Disturbed primary, c. 40 m tall forest, along trail near warden’s house, on leaves of unidentified plant, foliicolous in undergrowth, 20 November 1988, H. Sipman and P. Döbbeler (B 60 0178769).

Figure 38 Microtheliopsis uleana (B 60 0178769). a Herbarium packet. b Herbarium samples. c, d Ascomata on the surface of leaves. e Vertical section of ascoma. g–i Asci with ascospores. j–m Ascospores. Scale bars: c = 1000 µm, d =200 µm, e = 50 µm, f = 20 µm, g–m = 5 µm.