Microthyriaceae

Wu, Hai-Xia, Tian, Qin, Li, Wen Jing & Hyde, Kevin D., 2014, A reappraisal of Microthyriaceae, Phytotaxa 176 (1), pp. 201-212 : 202-203

Microthyriaceae

Taxa of the family Microthyriaceae are foliar epiphytes which are characterized by superficial, flattened thyriothecia, with cells of the upper wall radiating in a parallel arrangement from the central ostiole. The ostiole may or may not be surrounded by setae ( Ellis 1976, Wu et al. 2011a, Hongsanan et al. 2014). Asci are bitunicate, fusiform or obclavate to cylindro-clavate, and ascospores are 2-celled, hyaline to brown often with ciliate appendages ( Kirk et al. 2008, Wu et al. 2011a, Hyde et al. 2013). Hyde et al. (2013) accepted 13 genera (seven for which the sexual state and six for which the asexual state is known), while Hongsanan et al. (2014) add a new genus for which only the sexual state is known. In this paper we also include Phragmaspidium in Microthyriaceae .

Phragmaspidium Bat., Publções Inst. Micol. Recife 260: 109 (1960) MycoBank: MB 4018

Epiphytic on leaves, superficial mycelium lacking. Sexual state: Thyriothecia gregarious, circular, or some solitary, brown to black-brown, coriaceous, with prominent and darkened, raised, circular, central ostiole. Upper wall comprising neatly arranged radiating cells, basal layer poorly developed. Hamathecium comprising asci inclined towards the central ostiole, pseudoparaphyses lacking. Asci 8-spored, bitunicate, obclavate to cylindrical, apedicellate, lacking an obvious ocular chamber. Ascospores overlapping seriate, fusiform to clavate, with larger region above central septum, smooth-walled. Asexual state: unknown.

Type species:— Phragmaspidium corruscans ( Rehm 1913: 254) Bat. (1960: 110) .

Notes:— Phragmaspidium was introduced by Batista (1960) with P. corruscans as the type species and placed in Microthyriaceae . Phragmaspidium manaosense (Henn. 1904: 377) Bat. (1960: 113) and P. viniferae Bat. (1960: 114) have since been added. Wu et al. (2011a) followed the description of Rehm (1913) and suggested this genus should be placed in Micropeltidaceae . In this study, we examined the type species of Phragmaspidium which lacks a well-developed base, and the upper wall of thyriothecia which comprises cells radiating outwardly in parallel rows from the central raised papillate ostiole. Asci are bitunicate and ascospores are two-celled which are typical of Microthyriaceae . Phragmaspidium differs from other genera in Microthyriaceae in fusiform to clavate ascospores.

Phragmaspidium corruscans (Rehm) Bat., Publções Inst. Micol. Recife 260: 110 (1960) MycoBank: MB 113142 ( Fig. 1 )

≡ Micropeltis corruscan s Rehm, Philippine J. Sci. Sect. C Bot. 8: 254, 1913

Epiphytic on the lower surface of leaves, superficial mycelium lacking. Sexual state: Thyriothecia 27–61 µm high × 68–124 µm diam, gregarious, circular, or some solitary, slightly raised, brown to black-brown, coriaceous, with prominent and darkened, raised, circular, central ostiole. Upper wall comprising neatly arranged radiating cells and at margin occasionally branched, basal layer poorly developed. Hamathecium comprising asci inclined towards the central ostiole, pseudoparaphyses not observed or lacking. Asci 29–40 × 8–14.5 µm (x = 35.3 × 10.5 µm, n = 15), 8-spored, bitunicate, fissitunicate dehiscence not observed, obclavate to cylindrical, apedicellate, lacking an

202 Phytotaxa 176 (1) © 2014 Magnolia Press WU ET AL. obvious ocular chamber. Ascospores 11–17 × 3–5 µm (x = 13.1 × 3.8 µm, n = 20), overlapping 2–3-seriate, fusiform to clavate, with larger region above central septum, not constricted at the septum, 1–4 guttulate, smoothwalled. Asexual state: Unknown.

Material examined:— PHILIPPINES. Laguna Province: Mount Maquiling, near Los Baños, on leaves of Synedrella nodiflora (Asteraceae) , 7 January 1913, H. Rehm ( S F 8652, holotype).

Figures

FIGURE 1. Phragmaspidium corruscans (holotype). A, B. Appearance of pathogen on host leaf with thyriothecia. C, D. Squash mount of thyriothecium. Note upper wall of radiating cells. E, F. Section of thyriothecia. G–I. Asci. Note I mounted in cotton blue reagent. J–L. Ascospores. Note cells with guttules. Scale bars: B = 200 µm, C = 50 µm, E = 20 µm, D, F–I = 10 µm, J–L = 5 µm.