Thyridium pluriloculosum (Perdomo, Dania Garcia , Gene , Cano & Guarro) 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 pluriloculosum (Perdomo, Dania Garcia, Gene, Cano & Guarro) R. Sugita & Kaz. Tanaka comb. nov.

Figs 4 , 6B

Basionym.

Phialemoniopsis pluriloculosa Perdomo, Dania García, Gené, Cano & Guarro, Mycologia 105: 412 (2013).

Holotype.

USA, Nevada, human toe nail, D.A. Sutton, CBS H-20782, living culture CBS 131712 = UTHSC 04-7 = FMR 11070 (not seen).

Sexual morph.

Stromata scattered to grouped, pulvinate, circular to elliptical in outline, elevated beyond bark surface forming pustules, 0.6-0.7 mm high, 0.9-1.0 mm diam., dark brown to black. Ascomata perithecial, subglobose to ampulliform, 4-8 grouped, 700-780 µm high, 220-280 µm diam., immersed in stromata. Ascomatal wall 17-25 µm thick, composed of 7-10 layers of polygonal, 4-6.5 × 2-4 µm, dark brown cells. Ostiolar neck central, cylindrical, 400-430 µm long, 100-110 µm wide, periphysate. Paraphyses septate, unbranched, cylindrical, 92.5-110 µm long, 3.5-5.5 µm wide. Asci unitunicate, cylindrical, 110-175 × 9-12.5 µm (av. 145.6 × 10.3 µm, n = 15), broadly rounded at the apex, with a pronounced non-amyloid apical annulus, pedicellate (12.5-27.5 µm long), with 8 ascospores. Ascospores fusiform to ellipsoid, smooth, brown, with 3 transverse and 0-2 oblique or vertical septa, 13.5-18 × 6-8 µm (av. 15.5 × 7.3 µm, n = 50), l/w 1.7-2.6 (av. 2.1, n = 50).

Asexual morph (nature).

Conidiomata pycnidial, globose to subglobose, grouped, 220-300 µm high, 90-150 µm diam., immersed in stromata. Conidiomatal wall 8-18 µm thick, composed of 3-5 layers of polygonal, 3-4.5 × 2.5-4 µm, dark brown cells. Ostiolar neck central, cylindrical, 80-110 µm long, 90-110 µm wide, composed of polygonal cells, periphysate. Conidiophores hyaline, thin-walled, with branches bearing a group of 2-5 phialides terminally. Phialides tapering toward the tip, hyaline, 11-16 × 1-2 µm. Conidia ellipsoidal, with a slightly apiculate base, hyaline, smooth-walled, 3-4.5 × 1-2 µm (av. 3.7 × 1.5 µm, n = 50). Chlamydospores not observed.

Asexual morph (culture).

Coelomycetous asexual morph: Conidiomata pycnidial, scattered, single to grouped, superficial, globose to subglobose, 180-380 µm high, mostly 80-580 µm diam., up to 1170 µm diam. when grouped, often becoming cup-shaped when mature, surrounded by setose hyphae. Conidiomatal wall composed of polygonal to prismatic, 3-4.5 × 2.5-4 µm, dark brown cells. Setose hyphae erect, usually unbranched, septate, up to 360 µm long, 2-3 µm wide, pale brown. Conidiophores hyaline, thin-walled, simple or irregularly branched, with branches bearing a group of 2-5 phialides terminally. Phialides tapering toward the tip, hyaline, 10-25 × 1-2.5 µm. Conidia ellipsoidal, with a slightly apiculate base, hyaline, smooth-walled, in slimy masses, 3-4.5 × 1-2 µm (av. 3.8 × 1.4 µm, n = 50). Hyphomycetous synasexual morph: Conidiophores micronematous, mononematous, hyaline, simple or rarely branched. Phialides slightly tapering toward the tip, 4-11 × 1-2.5 µm, hyaline. Adelophialide absent. Conidia allantoid, hyaline, smooth-walled, in slimy heads, 3-9 × 1-2.5 µm (av. 6.2 × 1.7 µm, n = 50). Chlamydospores rarely present, solitary, 3.5-6.5 µm diam., hyaline to pale brown, thick- and rough-walled.

Culture characteristics.

Colonies on MEA at 25 °C attained 31-33 mm diam. after a week in the dark, whitish. On OA attained 32-36 mm diam., whitish to grey olivaceous (107). On PDA attained 32-33 mm diam., whitish to buff (45) (Fig. 6B ).

Specimen examined.

Japan, Aomori, Hirakawa, Hirofune, Shigabo Forest Park, on dead twigs of Betula maximowicziana , 10 October 2017, K. Tanaka, KT 3803 (HHUF 30648), living culture MAFF 247508.

Notes.

The conidia from aerial hyphae of strain KT 3803 were larger (3-9 × 1-2.5 µm) in culture than those of the original description of Thyridium pluriloculosum (3-5 × 1-2.5 µm; Perdomo et al. 2013). However, we identified this new collection on Betula maximowicziana as T. pluriloculosum , based on the high sequence homology of three loci with ex-type culture of this species (CBS 131712; 99.6% in ITS, 99.2% in act, and 99.5% in tub2). The sexual-asexual relationship of T. pluriloculosum was verified in this study. Although this species has been reported from clinical sources as an asexual morph ( Perdomo et al. 2013), the recently collected material represents a sexual morph on plant material.

In Thyridium , T. betulae has also been recorded on Betula sp. in France ( Roumeguère 1891). Although sequences of T. betulae are unavailable for molecular comparison, it is clearly different from T. pluriloculosum in having ascospores with 5-7 transverse and one longitudinal septum.

Figures

Figure 4. Thyridium pluriloculosum (A-Y KT 3803 = HHUF 30648 Z-AL culture KT 3803 = MAFF 247508) A-R sexual morph A, B appearance of stromata on substrate (B transverse sections) C ascomata in longitudinal section D ostiolar neck of ascoma E paraphyses F ascomatal wall G pseudostromatic tissue H-J asci K apex of ascus L-Q ascospores R germinating ascospore S-AF coelomycetous asexual morph (S-Y nature Z-AF culture) S appearance of conidiomata on substrate T conidiomata in longitudinal section U conidiomatal wall V conidiophores W phialide X, Y conidia Z-AB conidiomata in culture (AB multiloculate conidiomata) AC setose hypha of conidiomata AD conidiophores with groups of phialides AE, AF conidia AG-AL hyphomycetous synasexual morph AG, AH sporulation in culture AI phialide AJ, AK conidia AL chlamydospores. Scale bars: 1 mm (A, B, S, AB); 500 µm (C, Z, AA); 100 µm (D, T); 20 µm (AG, AH); 10 µm (E-J, L-R, U, V); 5 µm (K, W-Y, AC-AF, AI-AL).

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).