Cocconia placenta (Berk. & Broome) Sacc., Syll. Fung. (Abellini) 8: 738 (1889), Index Fungorum number: IF 183885
≡ Rhytisma placenta Berk. & Broome, J. Linn. Soc., Bot. 14: 131 (1873)
Habitat on living leaves of Symplocos spicata Roxb. Hyphae dark brown coloured, penetrate the plant tissue intracellularly. Sexual morph: Ascostromata solitary, superficial, globose to subglobose, wall dark brown to black with single locules, smooth, coriaceous, ostiolate. Ostiole usually wide porate, broadly papillate. Peridium comprising several layers of thick-walled textura angularis, comprising wide cells. Hamathecium of numerous, 1–2 µm diam., long, septate, cellular pseudoparaphyses. Asci 84–108 × 28–40 µm (x̄ =96 × 32 µm), 8-spored, bitunicate, clavate or broadly clavate, with short, furcate pedicel rounded and thickened at the apex, with a large ocular chamber. Ascospores 30–38 × 10–16 µm (x̄ =34 × 14 µm), uniseriate to partially overlapping, hyaline to pale olivaceous when immature, dark brown when mature, ellipsoid or cylindrical to clavate, thick-walled, 1-septate, distinctly constricted at septum, smooth-walled. Asexual morph: Undetermined.
Material examined: SRI LANKA. Peradeniya: on leaves of Symplocos spicata (Symplocaceae), November 1867, G.H.K. Thwaites (K (M) 409, holotype).
Notes: Cocconia is morphologically similar to genera within Parmulariaceae and Asterinaceae. The family Parmulariaceae differs from Asterinaceae in having ascostromata formed by pigmented cells in several layers, pseudoparaphyses, broadly ellipsoidal to obclavate asci, and lacking appressoria (Inácio & Cannon 2008, Inácio et al. 2012). Species of Asterinaceae have superficial hyphae mostly with appressoria, thyriothecia with a thin upper wall layer and poorly developed base and subglobose asci (Pirozynski & Shoemaker 1970, Inácio et al. 2012, Hongsanan et al. 2014). In this study we accept the placement of Cocconia within the family Parmulariaceae because of the ascostromata with several layers of pigmented cells, pseudoparaphyses and broadly ellipsoidal to obclavate asci. Cocconia differs from other genera in the way the ascomata connect to host surface, surface hyphae, absence or present of haustoria, ascospore shape and septation (Hyde et al. 2013).
Fig. 3. Cocconia placenta (holotype). A, B Ascostromata on host substrate. C Close up of ascostroma. D Section of ascostroma. E–G Asci with short, broad pedicel, containing four ascospores. H Apical part of the ascus having ocular chamber stained in Congo red. I Pseudoparaphyses. J Smooth-walled immature spore. K Ascospore stained with Congo red. L Mature dark brown ascospore. Scale bars: D=100 µm, E–G=40 µm, H=15 µm, I=5 µm, J–L=15 µm.