Ceraceosorus bombacis

Ceraceosorus bombacis (B.K. Bakshi) B.K. Bakshi 1976, in Cunningham, et al., Mycologia, 68(3), 640-654 (1976).

Diagnosis: Infection originally appearing on lower surface of the leaf, causing loss of color and subsequent yellowing in scattered, small, discrete areas, followed by production of thin, adherent, yellowish brown or pale brown fungus fruiting masses on yellowish infection spots, spreading and becoming coalescent as large, irregular, brown or rust-brown fruiting areas (Figure 1.10), eventually covering much of the lower leaf surface; upper surface of the leaf becoming bleached in areas directly opposite the lower surface infection spots, then turning yellowish and eventually brown; infection areas becoming necrotic; leaves wrinkling, curling, and falling prematurely. Fungus developing in the spongy parenchyma of the host as intracellular hyphae, erumpent through the stomata and epidermis of the lower surface of the leaf in sorus-Iike masses of hypha! tips, forming thin and effused fruiting masses, arid to waxy, subgelatinous-waxy when moist. Hyphae colorless or pale yellow, thin-walled or moderately thin-walled, branched, septate, without clamp connections, 1.5-2.5 µm broad. Hymenium increasing in thickness with age, indeterminate, containing pro basidia of all lengths and developmental stages (Figure 1.11), as well as narrow hyphae which may later develop into probasidia. Basidia (Figure 1.17) originating by transformation of hyphal tips to form persistent probasidia, colorless, sub-clavate or narrowly clavate, thick-walled at the apex when young, later becoming entirely thick-walled, attaining a size of (20-) 35-50 ( -85) X 3--6.5 µm, erupting apically to produce metabasidia; metabasidia cylindrical, thin-walled, up to 18 X 3--6 µm, terminally divaricate and forming two massive sterigmta ( 4-) 8-22 X 2-4 µm which become attenuated apically and form spicula (Figure 1.14) ; metabasidium and sterigmata collapsing after spore production and remaining as a frayed vestige at the probasidial apex. Basidiospores colorless, smooth, thin-walled, broadly allantoid to reniform or curved clavate, nonseptate or rarely one-septate, sometimes becoming one- or two septate during germination, (5.5-)8.5-14(-18.5) X 2-4.5 µm (Figure 1.15), when discharged often adhering laterally in pairs, germinating by germ tubes or rarely forming globose blastospores up to 2.5 µm diam. Conidiophores sometimes present, colorless, septate, branched, 30-440 X 1-2.5 µm. Conidia originating from conidiophores, from basidiospore germ tubes, or secondarily from existing conidia, colorless, smooth, thin walled, cylindric, one-several-celled, usually 8.5-18.5 ( -26) X 1-2.5 µm. Culture: Mycelial mat yellowish white to buff, sodden velvety at first, becoming waxy, often pulvinate in age, growing slowly (0.25 cm in seven da) ; hyphae colorless, branched, septate, without clamp connections, up to 2 µm broad; conidia abundant, colorless, cylindric, one-celled, 7-22 X 1.5 µm.

Index Fungorum Number: IF310466