Placoasterella schweinfurthii (Henn.) Theiss. & Syd., Annls mycol. 13(3/4): 236 (1915).
≡ Asterella schweinfurthii Henn., Fungi Ethiopia 1: 118 (1908)
Type: B 700014749, holotype; K 164019, isotype.
Pathogenic on upper surface of Dracaena leaves, forming blackened circles or irregular areas. Superficial hyphae not observed. Sexual state: Ascostromata superficial, or slightly erumpent on host, penetrating cells at host stomata, scattered or gregarious, carbonaceous, comprising thick-walled, dark brown to black-walled cells of textura angularis, multiloculate. Locules 120–173 diam×63–85 high μm (x= 168× 72μm, n=5), erumpent, opening with a pore at the centre, basal peridium poorly developed. Hamathecium lacking pseudoparaphyses. Asci 24–31×17 20μm (x = 28×18μm, n=6), 8-spored, bitunicate, fissitunicate, ovoid, pedicel absent or sometimes present but very short and rounded, apically rounded with a very thick opaque region, ocular chamber absent. Ascospores 17–20×6–9μm (x = 18×7μm, n=10), overlapping bi-seriate or tri-seriate, ellipsoid to fusoid, comprising 2-layers, 1-septate at the centre, with constricted at septum, upper cell slightly broader than the lower cell, hyaline to pale brown, smooth-walled, or slightly verruculose, with a sheath. Asexual state: Unknown.
Material examined: ERYTHREA, on leaves of Dracaena, 5 April 1892, J. Schweinfurter (B 700014749, holotype, K164019, isotype).
Notes: The isotype of P. schweinfurthii is located at K but is immature. The holotype form B is in better condition and is illustrated here.
Fig. 1 Placoasterella schweinfurthii (holotype). a Specimen label. b, c Ascostromata on leaves. d Erumpent locules. e, f Section through ascostroma showing locules. g, h Mature ascus. i–k Ascospores. Scale bars: e=50μm, f–h=20μm, i–k=15μm
