Thyridium revised: Synonymisation of Phialemoniopsis under Thyridium and establishment of a new order, Thyridiales Author Sugita, Ryosuke Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036 - 8561, Japan & The United Graduate School of Agricultural Sciences, Iwate University, 18 - 8 Ueda 3 chome, Morioka, Iwate 020 - 8550, Japan Author Tanaka, Kazuaki https://orcid.org/0000-0002-7037-0774 Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036 - 8561, Japan k-tanaka@hirosaki-u.ac.jp text MycoKeys 2022 2022-02-01 86 147 176 http://dx.doi.org/10.3897/mycokeys.86.78989 journal article http://dx.doi.org/10.3897/mycokeys.86.78989 1314-4049-86-147 2B1A9351D28153C4B5F319067A757969 Thyridium Nitschke, Pyrenomyc. Germ. 1: 110 (1867). Melanospora subgen. Bivonella Sacc., Syll. fung. (Abellini) 2: 464 (1883). Bivonella (Sacc.) Sacc., Syll. fung. (Abellini) 9: 989 (1891). Pleurocytospora Petr., Annls mycol. 21: 256 (1923). Sinosphaeria J.Z. Yue & O.E. Erikss., Syst. Ascom. 6: 231 (1987). Phialemoniopsis Perdomo, Dania Garcia , Gene , Cano & Guarro, Mycologia 105: 408 (2013). Type species. Thyridium vestitum (Fr.) Fuckel, Jb. nassau.Ver. Naturk. 23-24: 195 (1870) [1869-70]. Sexual morph. Stromata scattered to grouped, subepidermal to erumpent, yellowish to dark brown, red in KOH or not changing. Ascomata perithecial, subglobose to ampulliform, single to grouped, immersed in stromata to erumpent through host surface. Ascomatal wall composed of several layers of polygonal, dark brown cells. Ostiolar neck cylindrical, short or long, separated or convergent in upper stromata, periphysate. Paraphyses numerous, septate, unbranched, cylindrical, hyaline. Asci unitunicate, cylindrical, broadly rounded at the apex, with a pronounced non-amyloid apical annulus, pedicellate. Ascospores obovoid or ellipsoid, smooth, pale brown to brown, with several transverse and 0-3 longitudinal or oblique septa. Asexual morph. Coelomycetous and/or hyphomycetous morphs formed. Coelomycetous asexual morph: Conidiomata pycnidial, single to grouped, superficial or immersed in stromata, globose to subglobose, composed of polygonal to prismatic cells, often becoming cup-shaped when mature, surrounded by setose hyphae. Conidiomatal wall composed of several layers of polygonal, dark brown cells. Ostiolar neck cylindrical, central, periphysate. Setose hyphae erect, usually unbranched, septate, cylindrical, with slightly pointed or blunt tips, hyaline to pale brown, smooth-walled. Conidiophores hyaline, thin-walled, simple or irregularly branched, with branches bearing a small group of phialides terminally. Phialides swollen at the base, tapering at the tip, hyaline. Conidia obovoid to oblong, with a slightly apiculate base, hyaline, smooth-walled, in slimy masses. Hyphomycetous synasexual morph: Colonies effuse or sporodochial. Conidiophores micronematous, mononematous, hyaline, thin-walled, simple or irregularly branched, with branches bearing a small group of phialides terminally. Phialides swollen at the base, tapering at the tip, hyaline. Adelophialides absent or rarely present. Conidia ellipsoidal to allantoid, with a slightly apiculate base, hyaline, smooth-walled, in slimy head. Chlamydospores absent or rarely present, hyaline to pale brown, thick- and rough-walled. Notes. The newly obtained Thyridium collections formed synasexual morphs, coelomycetous and hyphomycetous, in culture that were similar to those of Phialemoniopsis , having coelomycetous and/or hyphomycetous conidial states in culture ( Perdomo et al. 2013 ). In this study, Phialemoniopsis is treated as a synonym of Thyridium because of their morphological similarities in asexual morphs and phylogenetic relatedness. The genus Pleurocytospora has been proposed as a synonym of Thyridium by culture studies ( Leuchtmann and Mueller 1986 ). We agree that the morphological features of Pleurocytospora , such as phialidic conidiogenous cells and hyaline, ellipsoidal conidia formed from both coelomycetous and hyphomycetous states ( Leuchtmann and Mueller 1986 ), are almost identical to those of the generic concept of Thyridium emended here. We accept both Bivonella and Sinosphaeria as synonyms of Thyridium , as proposed in previous studies ( Eriksson and Yue 1989 ; Checa et al. 2013 ). Sinosphaeria (typified by S. bambusicola = Thyridium chrysomallum ; Yue and Eriksson 1987 ) was established as a new genus without knowing the existence of Bivonella (typified by B. lycopersici ; Saccardo 1891 ). Both genera are characterised by yellowish stromata. The validity of these genera being synonymised under Thyridium is confirmed by the presence of T. flavostromatum , which has yellowish stromata, in the strongly supported Thyridium clade (Fig. 1 ). Figure 3. Thyridium flavostromatum ( A-S KT 3891 = HHUF 30647 T-AC culture KT 3891 = MAFF 247509) A-S sexual morph A-C appearance of stromata on substrate D, E ascomata in longitudinal section ( D in 2% KOH) F ostiolar neck of ascoma G paraphyses H ascomatal wall I-K asci L apex of the ascus M stipe of the ascus N-R ascospores S germinating ascospore T-AC hyphomycetous asexual morph T sporulation in culture U phialides V slimy conidial heads W conidiophores X phialide Y adelophialide Z-AB conidia AC chlamydospores and conidia. Scale bars: 1 mm ( A ); 500 µm ( B, C ); 100 µm ( D, E ); 50 µm ( F ); 10 µm ( G-K, M, S, U, V ); 5 µm ( L, N-R, W-AC ); 250 µm ( T ).