Neobelonopsis didymospora 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 didymospora Itagaki & Hosoya sp. nov.

Figs 6 , 13 , 14D

Etymology.

Named after two-celled ascospores.

Diagnosis.

Resembles Neobelonopsis bicolor , but distinguishable by sparse, minute guttles in living/dead ascospores, shorter asci, and wider host range including woody bamboos.

Holotype.

TNS-F-13501, Yakushima Island, Kagoshima Pref., Japan, 19 October 2005, on decaying culms of woody bamboos, ex-holotype culture NBRC 115354.

Description.

Apothecia superficial, without subiculum and scuta, 0.1-0.2 mm high, with blackish green (C100M100Y80-100K30) to black receptacle; disc 0.5-1 mm diam., white to bluish gray (C60M30-40Y20K60) when fresh, shrunk to 0.3-0.7 mm diam., cream (Y20K10) or olive (C40M40Y60-100K10) when dried. Ectal excipulum 30-50 µm thick at base, 20-25 µm thick at the upper flank to margin; cortical cells obovoid to clavate, (10-)12-15 × 7.5-10 µm at base, becoming slender and closely packed at the upper flank to margin, containing refractive vacuoles at the protruding cells when mounted fresh in water. Medullary excipulum 25-38 µm thick, frequently dichotomously branched, radially spreading toward the upper flask. Asci (50-)52-60(-65) × 5-7.5 µm, arising from croziers, with MLZ + apical pore. Ascospores 10-14(-16) × 2.5-3.5 µm, ellipsoid to fusiform, with subacute to acute extremes, frequently constrict at the septum, (0-)1-2-septate, hyaline, containing scattered small guttules. Paraphyses (45-)53-65 × 2.5-3(-4) µm, simple, (1-)2-3-septate, containing long refractive vacuoles in the apical cells and first 2-3 lower cells. Colony of NBRC 115354 on PDA flat, entire, dense, cottony to felted, dark brown (C60M80Y80-100K10) to beige (C10M20Y20-40K10) at the center, becoming pale brown toward to the edge, same colors at the reverse side, without soluble pigment and crystals; aerial mycelium sparse to dense, white to beige. Conidiophores solitary to occasionally aggregated on aerial hyphae, semi-macronematous, short, arising vertically or laterally from hyphae, pale to dark brown, smooth, thick-walled, sometimes branched 2-3 times, constricted at the septa, 2-3 µm width; phialides ampulliform, up to 15 µm long, 3.5 µm width at base, discrete or integrated, terminal or intercalary, hyaline to pale brown, thick-walled, with cylindrical to wide funnel-shape collarettes of 4.5-7.5 × 3 µm; conidia aseptate, subspherical to ellipsoid, abundantly aggregated in slimy head, 1.5-1.8 µm diam., hyaline, thin-walled.

Additional specimens examined.

TNS-F-13509, Yakushima Island, Kagoshima Pref., 19 October 2005, on decaying wood of Elaeocarpus japonicus , culture NBRC 115651; TNS-F-86178, Shishizuka Pond, Tsuchiura City, Ibaraki Pref., 29 October 2018, on decaying wood of Albizia julibrissin , culture NBRC 115657; TNS-F-88720, Shirokanedai, Meguro Ward, Tokyo, 6 July 2018, on dead stem of Trachycarpus fortunei ; TNS-F-86661 and TNS-F-86652, Yugashima, Izu City, Shizuoka Pref., 15 October 2021 on decaying culms of woody bamboos and unidentified wood, respectively; TNS-F-86670, Kawazu City, Kamo County, Shizuoka Pref., 16 October 2021, on unidentified decaying wood; TNS-F-86718, Mt. Katsuu, Nago City, Okinawa Pref., 27 October 2021, on decaying wood of Alnus sp.

Notes.

Neobelonopsis didymospora forms apothecia in autumn (October-December) and has a wide host range, but limited to woody plants, including woody bamboo. Neobelonopsis didymospora forms its asexual stage only on CMA (Fig. 6O, S ). This fungus is superficially similar to N. bicolor , but differs in fewer guttules in the cytoplasm.

Based on a BLAST search of the GenBank database, the closest hits to the ITS sequences of N. didymospora were three sequences of Mollisia sp. from New Zealand collected from the dead frond of Rhopalostylis sapida [MG195516; Identities=553/554 (99.8%), no gaps], fallen unidentified wood [MG195517; Identities=551/554 (99.5%), one gap], and fallen wood of Coriaria arborea [MG195518; Identities=511/511 (100%), no gaps]. The presence of these sequence data suggests that distribution of N. didymospora is not limited in Japan, but also in New Zealand.

Figures

Figure 6. Neobelonopsis didymospora (TNS-F- 13501, holotype) A fresh apothecia on decaying Bamboo culm B dried apothecia on decaying Bamboo culm C fresh apothecia on decaying unidentified wood (TNS-F- 86670) D dried apothecia on decaying unidentified wood (TNS-F- 86670) E vertical section of the apothecium (in LA) F reflective vacuoles in fresh marginal cells (in water) G vertical section at the basal apothecium (in lactic acid) H ascospores (in CB / LA) I asci with ascospores (in CB / LA) J paraphyses (in CB / LA) K fresh paraphyses with long refractive vacuoles (in water) L blue-stained apical pore of ascus (in Melzer's solution after 3 % KOH pretreatment) M crozier at the base of ascus (in CB / LA) N three months old colony on PDA O clusters of conidiophores (in CB / LA) P-S conidiophores with conidia (in CB / LA). Scale bars: 1 mm (A-D); 50 μm (E); 20 μm (O), 10 μm (F-M, P-S).

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.