Phacidium subcorticalis (Fuckel) W.J. Li & K.D. Hyde
≡ Ceuthospora subcorticalis Fuckel, Hedwigia 3: 160 (1864)
Index Fungorum number: IF557174, Facesoffungi number: FoF 07505
Saprobic on dead leaves of Distylium racemosum (Hamamelidaceae). Sexual morph: undetermined. Asexual morph: Conidiomata 250–300 µm diam., 170–250 µm high, black, stromatic, pycnidial, amphigenous on leaves, scattered to gregarious, subepidermal, initially immersed, then becoming partly erumpent, pulvinate to conical, irregularly plurilocular; individual locules irregular or globose to subglobose, 250–300 µm diam., 170–250 µm high, each with an ostiole. Ostioles 25–35 µm wide, centrally located, circular, rounded. Conidiomatal wall 20–35 µm wide, composed of outer several layers of thick-walled, brown cells of textura angularis, inner several layers, of thick-walled, hyaline cells of textura epidemoidea. Conidiophores 20–28 × 3.5–4.5 µm, arising from the inner wall layer of the conidiomata, hyaline, subcylindrical, septate, branched at the base. Conidiogenous cells 5–7 × 3–5 µm, hyaline, enteroblastic, phialidic, usually integrated, indeterminate, cylindrical, smooth. Conidia 20–28 × 3.5–4.5 µm (= 25.5 × 4 µm; n = 30), hyaline, cylindrical to subcylindrical, rounded at apex, narrowly truncate at the base, unicellular, thick- and smooth-walled, bearing a cone-shaped or irregular, subapical, mucoid appendage.
Culture characters: Colonies on PDA, reaching 7–8 cm after 7 d at 25–30 °C, white to brown with age, circular, flattened, dense, slightly cottony to felty, rounded and smooth at margins, reverse brown to dark brown. Mycelium composed of pale brown, cylindrical, branched, septate hyphae. Sporulation appearing after 4 weeks. Conidiomata formed from mycelium, brown to black, pycnidial, solitary or gregarious, globose or subglobose, multilocular, thick-walled. Conidia not observed.
Material examined: China, Yunnan, Kunming, on dead leaves of Distylium racemosum (Hamamelidaceae), 19 June 2014, Wen-Jing Li, WJL0040 (MFLU 19-2900, reference specimen designated here), living culture MFLUCC 15-0581 = KUMCC 15-0648; ibid., on dead leaves of D. racemosum (Hamamelidaceae), 25 June 2015, Wen-Jing Li, living culture MFLUCC 16-1149 = ICMP 21554 = KUMCC 15-0609, WJL0041 (MFLU 19-2901), WJL0041A (MFLU 19-2902).
Notes: A comparative study of the species described as asexual morphs of Phacidium (= Ceuthospora) show that our collections are similar to P. subcorticalis in form and dimensions of conidiomata and conidiogenous cells, but differs in dimensions of conidia. Our collections have much larger conidia than P. subcorticalis (10.5–14 × 2–2.5 ( = 12 × 2.5). However, the conidia dimensions could reflect hosts or geographic distribution. In addition, under P. anomala we have mentioned that conidial dimension alone cannot be used to distinguish species of Phacidium. Phacidium subcorticalis has been found on fallen leaves and inner surface of bark of Betula alba (Betulaceae) from Austria, Belgium, Finland (Nag Raj 1993). Therefore, our collection is regarded as a new record from China.
Phacidium subcorticalis (MFLU 19-2900, reference specimen) a Herbarium specimen. b, c Appearance of black conidiomata on the host. d, e Vertical sections of conidiomata. f Ostiole. g, h Section of peridium. i–k Conidiogenous cells and developing conidia. l–p Conidia. Scale bars: d = 200 µm, e = 100 µm, f–g = 20 µm, h–p = 10 µm.