Neobelonopsis microspora Itagaki & Hosoya, 2023

Itagaki, Hiyori & Hosoya, Tsuyoshi, 2023, A new genus Neobelonopsis and two new species of Trichobelonium (Helotiales, Ascomycota) discovered mainly from poaceous grasses native to Asia in Japan, MycoKeys 99, pp. 45-85 : 45

Neobelonopsis microspora Itagaki & Hosoya sp. nov.

Figs 7 , 13 , 14E

Etymology.

Named after its small ascospores.

Diagnosis.

Characterized by narrow, aseptate ascospores.

Holotype.

TNS-F-18068, Yuzawa Town, Minami-uonuma County, Niigata Pref., Japan, 18 July 2006, on decaying culms of Sasa sp., ex-holotype culture NBRC 115567.

Description.

Apothecia developed from scuta. Scuta superficial, scattered to gregarious, flat discoid, dark brown (C60M80Y80-100K60) to black, 125-450 µm diam., textura epidermoidea. Apothecia 0.1-0.2 mm high, with grayish brown (C10-30M30-40Y60K60) receptacle; disc 0.3-1.5 mm diam., cream (Y10-30K10) when dried. Ectal excipulum 25-35 µm thick at base, 15-25 µm thick at the upper flask to margin; cortical cells hemispherical to obpyriform, 12-15(-17) × 7.5-11 µm at base, becoming smaller and hyaline at the upper flask to margin. Medullary excipulum, 25-50 µm thick. Asci (40-)45-55(-63) × 3.7-5 µm, arising from croziers, with MLZ + apical pore. Ascospores (7.5-)9.5-12.5(-16) × 2-2.5 µm, cylindrical to subcylindrical-fusoid-clavate with rounded extremes, aseptate, without guttules. Paraphyses (47-)52-62(-67.5) × 2-3.5(-4) µm, simple, rarely branched, (1-)2-3-septate. Subiculum thinly developed at the surface of substrates, sparse overall, shiny brown; subicular hyphae straight to undulate, frequently forming monilioid cells at the tip of the hyphae, 3-5 µm diam. with 0.5-1 µm thick-walls, perpendicularly branched. Colony of NBRC 115567 on PDA entire, flat to winkled at the center, floccose to felted, gray (K50-70) from the surface, darker from the reverse, without soluble pigment and crystals; aerial mycelium sparse to dense, white to pale gray. Conidiophores solitary to occasionally aggregated, semi-macronematous, short, arising vertically or laterally from fascicular hyphae, pale to dark brown, smooth, thick-walled, sometimes branched, constricted at the septa, 2.5-3 µm width; phialides ampulliform, up to 15 µm long, 3-4 µm width at base, discrete or integrated, terminal or intercalary, thick-walled, with cylindrical to long funnel-shape collarettes; collarettes of 6-8 × 2-3 µm, dark brown, occasionally covered with granules; conidia aseptate, cylindrical oblong to fusiform, abundantly aggregated in slimy heads, 4-5 × 1-1.5 µm, hyaline, thin-walled.

Additional specimens examined.

TNS-F-16804, Sugadaira Montane Research Center, Ueda City, Nagano Pref., 7 July 2007, on unidentified fallen branches, culture NBRC 115653; TNS-F-17105, Nozori Lake, Kuni Village, Agatsuma County, Gunma Pref., 15 May 2004, on decaying culms of Sasa sp., culture NBRC 115650; TNS-F-86453, Shiromine, Shiroyama City, Ishikawa Pref., 18 June 2021, on decaying culms of Sasa palmata , culture NBRC 115660; TNS-F-86584, Kawakami Town, Noboribetsu City, Hokkaido, 2 August 2021, on decaying culms of Sasa kurilensis , culture NBRC 115662.

Notes.

The minimum length of the ascospores of N. microspora is the shortest in Neobelonopsis but its maximum length is overlapped with the other species. This fungus resembles B. eriophori Raitv. in macroscopic appearance of apothecia and in having short, aseptate ascospores (16-19 × 3-3.5 µm), but ascospores of B. eriophori become uniseptate at maturity while that of N. microspora remain aseptate ( Raitviir 2003),

Neobelonopsis microspora produces conidiophores only on CMA, and the conidia germinate frequently (Figs 7J, K , 14E ). The asexual morphology of N. microspora is very similar to that of N. cinnabarina , with long collarets and oblong conidia, except conidiophores do not form a sporodochium.

Figures

Figure 7. Neobelonopsis microspora (TNS-F- 18068, holotype) A dried apothecia on the decaying culm of Sasa sp. B immature apothecia protruding from the stromata (arrows) C vertical section of the apothecium (in LA) D ascospores (in CB / LA) E asci with ascospores (in CB / LA) F paraphyses (in CB / LA) G blue-stained apical pore of asci (in Melzer's solution after 3 % KOH pretreatment) H, I croziers at the base of asci (in CB / LA) J conidiophores with pigmented collarets K conidiophores. Scale bars: 0.5 mm (A, B); 50 μm (C); 10 μm (D-K).

Figure 13. Line-drawings of the Neobelonopsis and Trichobelonium species I vertical section of the apothecium showing the marginal structure of ectal excipulum, medullary excipulum, and hymenium II asci III paraphyses IV ascospores. Scale bars: 10 μm.

Figure 14. Asexual morph and hyphal structures of the Neobelonopsis and Trichobelonium species A conidiophores of N. acutata B monilioid hyphae of N. bicolor C conidiophores with conidia of N. cinnabarina D conidiophores with conidia of N. didymospora E conidiophores with conidia of N. microspora F conidiophores with conidia of N. multiguttata G conidiophores with conidia of N. obtusa H conidiophores with conidia of T. albobarbatum I hyphal mass with melanized appressorium-like structure of T. miscanthi. Scale bars: 10 μm.