Microcallis phoebes Syd., Annls mycol. 24(5/6): 338 (1926), Figure 15
MycoBank number: MB 274276; Index Fungorum number: IF 274276; Facesoffungi number: FoF 10349;
Epiphytic on the lower surface of leaves, appearing as black dots scattered. Mycelium 2–3.5 μm, composed of branched-reticulate, septate, olivaceous to blackish-brown hyphae. Sexual morph: Ascomata 75–180 × 30–50 μm (x̅ = 148 × 43 μm, n=10), scattered, developing beneath a mycelial pellicle, globose-depressed, attaching it to the leaf surface, olivaceous-brown, membranous, pseudo-ostiolate. Setae 140–250 × 2–5 μm, wider at the base and tapering to the apex, scattered, dark brown to black, erect, obtuse. Wall of ascoma up to 50 μm thick, pseudoparenchymatous, composed of cells of textura angularis at the outside, becoming light brown and flattened in the inner region. Hamathecium 1–2.5 μm, comprising filiform, hyaline, septate, branched paraphyses. Asci 28–55 × 12–18 μm (x̅ = 42 × 15 μm, n=10), 8-spored, bitunicate, clavate to ellipsoid, subsessile or sessile. Ascospores 15–22 × 5–7 μm (x̅ = 19 × 6 μm, n=10), overlapping bi-seriate or multi-seriate, oblong-clavate, hyaline, 1-septate, constricted at the septum, thick-walled, smooth-walled, without a mucilaginous sheath. Asexual morph: Undetermined.
Material examined: Costa Rica, San Pedro de San Ramon, on leaves of Phoebe sp. (Lauraceae), 23 January 1925, H. Sydow (E00429570, syntype).
Figure 15 Microcallis phoebes (E00429570, syntype). a, b Herbarium material. c–e Ascomata on the host surface. f–h Squash mount of ascomata. Note upper wall of radiating cells at the margin. i–k Vertical section of ascomata. l–q Asci. s–u Ascospores. Scale bars: c = 1000 μm, d = 200 μm, e = 100 μm, f, g, i = 50 μm, h, j = 20 μm, k–r = 10 μm, s–u = 5 μm.