Thyridium punctulatum (I. Hino & Katum.) R. Sugita & Kaz. Tanaka, 2022

Sugita, Ryosuke & Tanaka, Kazuaki, 2022, Thyridium revised: Synonymisation of Phialemoniopsis under Thyridium and establishment of a new order, Thyridiales, MycoKeys 86, pp. 147-176 : 147

Thyridium punctulatum (I. Hino & Katum.) R. Sugita & Kaz. Tanaka comb. nov.

Figs 5 , 6C

Basionym.

Pleospora punctulata I. Hino & Katum., Icones Fungorum Bamb. Jpn.: 181 (1961).

Holotype.

Japan, Shizuoka, Fuji Bamboo Garden, on dead twigs of Phyllostachys nigra var. henonis , 1 April 1958, K. Katumoto, YAM 21851.

Epitype.

Japan, Yamaguchi, Hagi, Akiragi, near Chikurindoro-park, on dead twigs of Phyllostachys nigra var. nigra , 26 March 2018, K. Tanaka, K. Arayama and R. Sugita, KT 3905 (HHUF 30649 epitype designated here; MBT 10004137), ex-epitype culture MAFF 247510.

Sexual morph.

Stromata scattered to grouped, subepidermal, becoming erumpent to superficial, 0.5-1.2 mm long, 0.2-0.4 mm wide, dark brown. Ascomata perithecial, subglobose to conical, single to 2-3 grouped, 130-190 µm high, 140-230 µm diam., immersed in stromata to erumpent through host surface. Ascomatal wall 7-15 µm thick, composed of 3-5 layers of polygonal, 3-6.5 × 1-4.5 µm, dark brown cells. Ostiolar neck central, cylindrical, 37-85 µm long, 37-63 µm wide, periphysate. Paraphyses numerous, septate, unbranched, cylindrical, hyaline, 77-103 µm long. Asci unitunicate, cylindrical, 67.5-105 × 7.5-11.5 µm (av. 82.9 × 9.4 µm, n = 60), broadly rounded at the apex, with a pronounced non-amyloid apical annulus, short-stalked (3.5-11.5 µm long), with 8 ascospores. Ascospores ellipsoid to oblong, smooth, pale brown, with 3 transverse and 1-2 vertical septa, 10-15 × 5-9 µm (av. 12.8 × 7.0 µm, n = 60), l/w 1.4-2.4 (av. 1.8, n = 60).

Asexual morph (nature).

Not observed.

Asexual morph (culture).

Coelomycetous asexual morph: Conidiomata pycnidial, single to grouped, superficial, globose to subglobose, 100-250 µm high, 170-620 µm diam., composed of polygonal to prismatic, 3.5-7.5 × 2.5-4 µm cells, often becoming cup-shaped when mature, surrounded by setose hyphae. Setose hyphae erect, usually unbranched, septate, up to 225 µm long, 1.5-2.5 µm wide, pale brown. Conidiophores hyaline, thin-walled, simple or irregularly branched, with branches bearing a group of 2-5 phialides terminally. Phialides swollen at the base, tapering at the tip, 7-20 × 1-3 µm, hyaline. Conidia ellipsoidal to obovoid, with a slightly apiculate base, hyaline, smooth-walled, in slimy masses, 2-3.5 × 1-2 µm (av. 2.9 × 1.4 µm, n = 50). Hyphomycetous synasexual morph: Conidiophores micronematous, mononematous, hyaline, thin-walled, simple or irregularly branched, with branches bearing a group of 2-3 phialides terminally. Phialides swollen at the base, tapering at the tip, hyaline, 3-9 × 1-2 µm. Adelophialide absent. Conidia ellipsoidal to allantoid, hyaline, smooth-walled, in slimy heads, 2.5-8 × 1-3 µm (av. 4.3 × 1.6 µm, n = 87). Chlamydospores rarely present, solitary or chained, 4-5.5 µm diam., hyaline to pale brown.

Culture characteristics.

Colonies on MEA at 25 °C attained 31-32 mm diam. after a week in the dark, granulose, whitish. On OA attained 38-39 mm diam., granulose, whitish. On PDA attained 35-36 mm diam., whitish to buff (45) (Fig. 6C ).

Other specimen examined.

Japan, Iwate, Morioka, Ueda, Campus of Iwate University, on dead culms of Phyllostachys pubescens , 17 February 2003, K. Tanaka and Y. Harada, KT 1015 (HHUF 29350), living culture JCM 13159 = MAFF 239669.

Notes.

This species has been described from Phyllostachys nigra var. henonis , as a species of Pleospora ( Dothideomycetes; Hino 1961). Our phylogenetic analysis (Fig. 1 ) shows that this species is a member of the genus Thyridium ( Sordariomycetes). The morphological features of this species are consistent with those of the genus Thyridium , including immersed to erumpent, single to grouped, perithecial ascomata with a cylindrical ostiolar neck, unitunicate asci and muriform, pigmented ascospores ( Eriksson and Yue 1989). Therefore, we propose a new combination, T. punctulatum , for Pleospora punctulata .

Figures

Figure 1. Maximum-likelihood tree of Sordariomycetes based on combined LSU, rpb 2 and tef 1 sequence. ML bootstrap proportion (BP) greater than 70 % and Bayesian posterior probabilities (PP) above 0.95 are presented at the nodes as MLBP / Bayesian PP and a node not present in the Bayesian analysis is shown with ' x'. A hyphen (' - ') indicates values lower than 70 % BP or 0.95 PP. Ex-holotype, isotype, paratype and epitype strains are shown in bold and the newly obtained sequences are shown in red. Strains previously described as Phialemoniopsis species are marked with a blue circle. The scale bar represents nucleotide substitutions per site.

Figure 5. Thyridium punctulatum (A-N, Q, R KT 3905 = HHUF 30649 O, P YAM 21851 S, T, W-AB culture KT 1015 = JCM 13159 = MAFF 239669 U, V, AC-AK culture KT 3905 = MAFF 247510) A-R sexual morph A, B appearance of stromata on substrate C, D ascomata in longitudinal section E ostiolar neck of ascoma F paraphyses G ascomatal wall H-J asci K apex of ascus L stipe of ascus M-Q ascospores R germinating ascospore S-AD coelomycetous asexual morph S-V conidiomata in culture W conidioma in longitudinal section X conidiomatal wall Y setose hyphae of conidiomata Z, AA conidiophores AB phialides AC, AD conidia AE-AK hyphomycetous synasexual morph AE conidiophore AF slimy head AG phialide AH-AJ conidia AK chlamydospores. Scale bars: 1 mm (A, S); 500 µm (B); 100 µm (C, W); 50 µm (D); 10 µm (E-J, L, R, X-AA, AE, AF); 5 µm (K, M-Q, AB-AD, AG-AK); 200 µm (T-V).

Figure 6. Colony characters of Thyridium species used in this study on MEA (bottom right), OA (bottom left) and PDA (upper) within 1 week at 25 ° C in the dark A T. flavostromatum (culture KT 3891 = MAFF 247509) B T. pluriloculosum (culture KT 3803 = MAFF 247508) C T. punctulatum (culture KT 3905 = MAFF 247510). Scale bars: 3 cm (A-C).