Discosia fagi W.J. Li, J. K. Liu & K.D. Hyde, 2015

Li, Wen-Jing, Liu, Jian-Kui, Bhat, D. Jayarama, Camporesi, Erio, Dai, Dong-Qing, Xu, Jian-Chu, Hyde, Kevin D. & Chomnunti, Putarak, 2015, Molecular phylogenetic analysis reveals two new species of Discosia from Italy, Phytotaxa 203 (1), pp. 37-46 : 43-44

Discosia fagi W.J. Li, J. K. Liu & K.D. Hyde sp. nov. FIGURE 3 .

Index Fungorum number: IF550759

Faces of Fungi number: FoF00331

Etymology: Referring to the host genus, Fagus , from which the species was isolated.

Holotype: MFLU 14–0299

Saprobic on dead leaves of Fagus sylvatica . Sexual state: Unknown. Asexual state: coelomycetous. Conidiomata 200–500 (x = 300) μm diam., 30–75 μm high, pycnidial, stromatic, epiphyllous or hypophyllous, solitary, scattered to gregarious or confluent, applanate to disc-like, partly immersed or superficial, rounded to irregular in outline, glabrous, unilocular or divided into several locules by tissue cells of textura porrecta, ostiolate. Peridium 10–15 μm thick, composed of 5–6 layers of cells, with outer 2–3 layers dark brown, inner 1–2 layers colourless, comprising thin-walled cells of textura angularis. Ostiole circular, papillate. Conidiophores reduced to conidiogenous cells, arising from the upper cells of the basal stroma. Conidiogenous cells 4–8 × 1–3.5 (x = 6 × 2) μm, subcylindrical to narrowly flaskshaped, developing directly on the inner-most layer of peridium-wall, phialidic, each producing a single conidium, integrated, hyaline, smooth. Conidia 13–20 × 2.5–3 μm (x = 17 × 2.8 μm, n = 50), cylindrical to subcylindrical, straight or slightly curved, 3-septate, slightly constricted at the septa, with cells of equal width and colour (yellowish to colourless); basal cell obconic, with a truncate base; 2 median cells subcylindrical, second cell adjacent to the base 5–9 μm (x = 7 μm) long, the third cell adjacent to the apex 2–4 μm (x = 3 μm) long; apical cell subconical with a rounded apex; apical and basal cells each with a subapical and suprabasal, unbranched, filiform, flexuous or straight appendage; apical appendage 6–10 μm (x = 8 μm), basal appendage 6–10 μm (x = 8 μm).

Material examined: — ITALY, Forlì-Cesena [FC], Montefalco, Santa Sofia, on dead leaves of Fagus sylvatica , 2 September 2012, Erio Camporesi, IT-722 ( MFLU 14–0299 holotype). ibid. ( KUN! HKAS 83870, isotype)

Notes: — There are six species so far described from Fagus sylvatica , namely, D. artocreas , D. faginea , D. maculiformis ( Nag Raj 1993) , D. minuta ( Farr & Rossman 2011) , as well as the new species D. italica and D. fagi . However, the original specimen of D. maculiformis Syd. & P. Syd. has not been examined, thus the morphological characters of this species are not clear. Comparative morphological characters of the D. fagi and D. artocreas show that D. fagi share similar characters with D. artocreas in the form of conidiomata and conidia, but differ in conidiogenous cells (phialidic in D. fagi and annellidic in D. artocreas ). Moreover, the differences between D. fagi and D. faginea can to be observed in the shape of the conidiomata (unilocular to muti-locular, applanate to disc-like in D. fagi and monoloculate, discshaped in D. faginea ), and the pigmentation of conidia, with D. fagi conidia cells having equal width and colour, while in D. fagi the two middle cells are wider and darker than the two end cells. Furthermore, D. fagi can be distinguished from D. minuta in dimensions of conidiomata (200–500 (x = 300) μm diam. in D. fagi versus 120–170 μm diam. in D. minuta ), and appendage (6–10 μm in D. fagi , whereas up to 10 μm in D. minuta ). The differences between D. italica and D. fagi are further explained in the discussion section.

Figures

FIGURE 3. Discosia fagi (MFLU 14–0299, holotype).A. Specimen. B, C. Black conidiomata on the host surface. D, E. Vertical section of conidioma. F. Section of peridium. G–H. Conidiogenous cells and developing conidia. I–L. Conidia. Scale bars: B = 500 μm. C = 200 μm. D, E = 100 μm. F–L = 5 μm.