Helicosporium tongrenense S. Bai, L. J. Chen, & J. Ma, 2025

Bai, Song, Wang, Fang, Wan, Su-Ran, Lv, Xiao-Kang, Chen, Li-Jun, Wu, Rong & Ma, Jian, 2025, Two novel Helicosporium species (Tubeufiaceae, Tubeufiales) from southern China based on morphological and molecular evidence, MycoKeys 124, pp. 159-176 : 159-176

Helicosporium tongrenense S. Bai, L. J. Chen, & J. Ma sp. nov.

Fig. 3

Etymology.

‘‘ tongrenense ” refers to the place ‘‘Tongren City,” from where the holotype was collected.

Holotype.

HKAS 128925

Description.

Saprobic on decaying wood in a terrestrial habitat. Asexual morph Undetermined. Sexual morph: Ascomata superficial, seated on a subiculum, solitary, scattered, globose to subglobose, bright reddish yellow to brown yellow, with central narrow ostiole, no observed setae. Peridium composed of several layers of brown to dark brown cells of textura angularis, outer layer brown cells, and inner layer pale brown to hyaline cells. Hamathecium comprising numerous, filiform, septate, branched, hyaline pseudoparaphyses. Asci 90.5–143 × 11.5–14.5 µm (x ̄ = 107.5 × 13 μm, n = 20), 8 - spored, bitunicate, fissitunicate, cylindrical to clavate, short-pedicellate, apically rounded, basally flexious. Ascospores 37–48 × 3.5–5.5 µm (x ̄ = 43 × 4 μm, n = 20), overlapping 2–3 seriate, elongate-fusiform, tapering towards narrow, widest at the central part, subacute ends, straight to slightly curved, guttules, multi-septate, hyaline, smooth-walled.

Culture characteristics.

Ascospores germinating on PDA, producing germ tubes within 19 hours. Colony on PDA reaching 0.7 cm diameter after 90 days at room temperature (approximately 25 ° C), circular or irregular, flat, with an entire margin, and pale brown to yellowish brown in color.

Material examined.

• China, Guizhou Province, Tongren City , Jiangkou County, on decaying wood in a terrestrial habitat, 20 May 2022, Xia Tang, JK 1.1 ( HKAS 128925 = GZAAS 23–0027 , holotype), ex-type living cultures GZCC 23–0026 ; Ibid., JK 4 ( GZAAS 25–0670 , paratype), living culture GZCC 25–0640 .

Notes.

Morphologically, Helicosporium tongrenense ( HKAS 128925 ) resembles H. flavum ( MFLU 17–0704 ) in having solitary, scattered, globose to subglobose, bright reddish-yellow to brown-yellow ascomata; 8 - spored, bitunicate, fissitunicate, cylindrical to clavate asci; and elongate-fusiform, straight to slightly curved, multi-septate, hyaline ascospores ( Brahmanage et al. 2017). However, H. tongrenense ( HKAS 128925 ) differs from H. flavum ( MFLU 17–0704 ) by shorter ascospores (37–48 μm vs. up to 60 μm) ( Brahmanage et al. 2017). Additionally, H. flavum possesses short, setae-like projections, which are absent in H. tongrenense ( Brahmanage et al. 2017). Phylogenetically, our isolates ( GZCC 23–0026 and GZCC 25–0640 ) form a sister clade to H. jiangkouense ( HKAS 128933 ), with 100 % MLBS and 1.00 BYPP support. However, comparison of the ITS, LSU, tef 1 - α, and rpb 2 sequence data between H. tongrenense ( GZCC 23–0026 ) and H. jiangkouense ( HKAS 128933 ) revealed nucleotide base differences of 26 / 526 bp (4.9 %, including 1 gap), 51 / 834 bp (6.1 %, including 3 gaps), 1 / 884 bp (0.1 %, including 1 gap), and 1 / 916 bp (0.1 %, with no gaps), respectively. Notably, the asexual morph of H. jiangkouense is the only form observed to date ( Ma et al. 2024 b). Therefore, based on both multigene phylogenetic analyses and morphological differences, we introduce Helicosporium tongrenense as a novel species.

Figures

Figure 3. Helicosporium tongrenense (HKAS 128925, holotype). a. Ascomata on host surface; b – d. Vertical sections of ascomata and peridium; e – h. Asci; i – n. Ascospores; o, p. Colonies on PDA from above and below after 3 months of incubation at room temperature. Scale bars: 50 µm (b – e), 20 µm (f – h), 10 µm (i – n).