Phellostroma Syd. & P. Syd., Philipp. J. Sci., C, Bot. 9(2): 185 (1914)
Faceoffungi number: FoF 07489
Ascomycota, genera incertae sedis
Saprobic on dead fructification of Areca sp. (Arecaceae) (Sutton and Kobayashi 1969). Sexual morph: undetermined. Asexual morph: Conidiomata black, stromatic, pycnidial, solitary, superficial, cushion-shaped, multilocular, glabrous, ostiolate. Ostiole single to each locule, cylindrical, with long neck of varying length, centrally located. Conidiomatal wall composed of relatively thick-walled, brown to pale brown cells of textura angularis in most parts of the conidiomata, becoming dark brown cells toward periphery, merging with thick-walled, paler cells of textura prismatica in the inner locular wall. Conidiophores arising from inner layer of the locular wall, hyaline, cylindrical to subcylindrical, septate, smooth-walled. Conidiogenous cells hyaline, holothallic, cylindrical, determinate, smooth-walled. Conidia hyaline, arthric, elliptical, somewhat truncated at both ends, unicellular, straight, smooth-walled, guttulate, formed by disarticulation of the conidiogenous cells from the conidiophore, produced in long, branched chains with the youngest conidia at the base (adapted from Morgan-Jones 1974).
Type species: Phellostroma hypoxyloides Syd. & P. Syd., Philipp. J. Sci., C, Bot. 9(2): 185 (1914)
Notes: Phellostroma was described from dead fructification of Areca sp., with P. hypoxyloides as type species (Sydow and Sydow 1914). Phellostroma resembles the asexual morph of Pycnopeziza, Phacidiella, Sirozythiella, Trullula and Vouauxiella Petr. & Syd., in having arthric conidia formed by disarticulation of the conidial chain, with the oldest conidium at the apex (Morgan-Jones 1974, Sutton 1980). However, the asexual morph of Pycnopeziza has cylindrical conidia bearing appendages, which is absent in Chondropodiella, Phacidiella, Phellostroma, Sirozythiella, Trullula and Vouauxiella. Vouauxiella and Trullula have brown or dark brown conidia, which distinguish them from the hyaline conidia in Chondropodiella, Phacidiella, Phellostroma, and Sirozythiella (Sutton 1980, Wijayawardene et al. 2016). Phellostroma differs from Chondropodiella, Phacidiella and Sirozythiella by its cushion-shaped, multilocular, glabrous, ostiolate conidiomata. Sirozythiella was separated from Chondropodiella and Phacidiella by its septate conidia, and textura angularis to textura intricata conidiomatal wall (Morgan-Jones 1974, Sutton 1980). Chondropodiella differs from Phacidiella by its cylindrical to cylindrical-subulate, beaked conidiomata with unbranched conidial chains (Morgan-Jones 1974, Sutton 1980).
von Höhnel (1918b) studied the type collection of P. hypoxyloides and considered the fungus to be an ascomycete. Sutton and Kobayashi (1969) re-examined the type species and could not find any structures of asci and ascospores, and considered it might be a coelomocyte. Morgan-Jones (1974) provided a detailed description and illustration of P. hypoxyloides. The second species, P. tsugae Tak. Kobay. was described from Tsuga sieboldii by Kobayashi (1964). However, this taxon was proved to not be congeneric with the type species by Sutton and Kobayashi (1969), because of its distinct morphology of conidiogenous cells (holoblastic) and conidia (ovoid to broadly fusiform with appendages at each end). Phellostroma tsugae was therefore designated as the type species for a new genus Strasseriopsis. Phellostroma is monotypic and no molecular data is available. Fresh collections are needed to place Phellostroma in a natural group.
Distribution: Philippines (Sutton and Kobayash 1969).
Phellostroma hypoxyloides (redrawn from Morgan-Jones 1974) a Vertical section of conidiomata. b, c Enlarged view of conidiomatal wall. d Conidia. e Conidiogenous cells and developing conidia.
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.