Fungalpedia – Note 691, Placosoma
Placosoma Syd.
Citation when using this data: D. S. Marasinghe et al. 2023 (in prep.) – Fungalpedia, Ascomycota.
Index Fungorum, Facesoffungi, MycoBank, GenBank.
Classification: Asterinaceae, Asterinales, Dothideomycetidae, Dothideomycetes, Pezizomycotina, Ascomycota, Fungi
Colonies epiphytic on the surface of leaves, appearing as subcuticular to circular, blackened areas. Surface mycelia with appressoria absent. Sexual morph: Ascostromata superficial, flattened, scattered, solitary, subcuticular, circular to elliptical, multi-loculate, carbonaceous, hyphostroma present. Locules conical, radially arranged, opening by linear or stellate fissures. Internal stroma comprises numerous 1.5–2 μm, hyaline, filiform pseudoparaphyses. Asci 8-spored, bitunicate, subglobose to oblong or oblong-ovate, hyaline, apically rounded with thickened ocular chamber, apedicellate. Ascospores overlapping 2–4-seriate, broadly ellipsoidal, hyaline. Asexual morph: Hyphomycetous, conidiophores develop on superficial hyphae. Conidia blastic, solitary, brown to dark brown, narrowly obclavate, 2–3-septate, slightly constricted, narrowed towards the darker basal scar (Sydow 1924; Sivanesan 1984; Hongsanan et al. 2014a).
Notes: Sydow (1924) introduced Placosoma with the type species of P. nothopanacis. This genus is characterized by having superficial, circular, blackened, flattened, carbonaceous ascomata, subglobose to oblong asci and broadly ellipsoidal, 1-septum, ascospores (Hongsanan et al. 2014a). Lumbsch and Huhndorf (2010) placed Placosoma in Asterinaceae. However, Hongsanan et al. (2014a) re-examined the type species P. nothopanacis and placed it in Parmulariaceae.
Type species: Placosoma nothopanacis Syd., Annls mycol. 22(3/6): 303 (1924)
Other accepted species: species Fungorum – search Placosoma.
References
Hongsanan S, Li YM, Liu JK et al 2014a – Revision of genera in Asteri- nales. Fungal Divers 68:1–68.
Lumbsch HT, Huhndorf SM 2010 – Outline of Ascomycota 2009. Myconet 14:1–64.
Sivanesan A 1984 – The bitunicate ascomycetes and their anamorphs. J. Cramer, Vaduz, p 701.
Sydow H 1924 – Beiträge zur Kenntnis der Pilzflora Neu-Seelands. Ann Mycologici 22:303.
Entry by
Diana Sandamali Marasinghe, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand School of Science, Mae Fah Luang University, Chiang Rai, 57100, Thailand, Mushroom Research Foundation, 128 M.3 Ban Pa Deng T. Pa Pae, A. Mae Taeng, Chiang Mai, 50150, Thailand
Published online 29 August 2023