Arthrinium neogarethjonesii
Arthrinium neogarethjonesii D.Q. Dai & K.D. Hyde, in Hyde et al., Mycosphere 11(1): 424 (2020)
Index Fungorum number: IF555481
Holotype – HKAS 102408
Saprobic on dead bamboo culms. Sexual morph: Stromata 1–2 mm long, 0.25–0.5 mm wide, 175–250 μm high, scattered to gregarious, immersed, becoming slightly erumpent through the host tissue, black to dark brown, fusiform to elongated ellipsoid, with a central slit-like opening at the top. Ascomata perithecial, 125–230 μm high, 120–230 μm diam., arranged in rows, clustered, gregarious, with 2–7 perithecia forming groups immersed in stromata and surrounding by stromatic tissue, ellipsoidal to subglobose, or obpyriform with a slightly flattened base, brown to reddishbrown, membranous. Ostiole raised from centre of perithecia, internally lined with periphyses. Peridium 15–25 μm thick, composed of dark brown to reddish brown to hyaline cells of textura angularis. Stromatic cells between perithecia 150–350 μm wide, comprising host and fungal tissues, composed of elongated, brown cells of textura angularis. Paraphyses dense, long, 3.5–6 μm wide, septate, un-branched with the wider base and thinner apex. Asci 95–125 × 20–25 μm (x̅ = 97.6 × 21.3 μm, n = 20), 8-spored, unitunicate, clavate, apedicellate, apically rounded. Ascospores 25–30 × 9.5–11 μm (x̅ = 29.1 × 10.3 μm, n = 20), 2-seriate, overlapping, 1-septate, ellipsoidal, with a small lower cell and a large upper cell, with many guttules, hyaline, smooth-walled, with a thick gelatinous sheath, 3–10 μm wide. Asexual morph: Coelomycetous or Hyphomycetous on substrates, Conidiomata 450–600 μm wide × 1–1.5 mm long, 150–250 μm high, solitary to gregarious, immersed, then raised from host tissue when mature, ellipsoid to irregular, black, coriaceous. Conidiomata wall composed of one layer of dark brown to brown to hyaline cells of textura angularis. Conidiophores mother cells 4.5–6 × 3.5–4.5 μm (x̅ = 5.4 × 4.3 μm, n = 20), cylindrical, aseptate. Conidiogenous cells 10–48 × 4–5.5 μm (x̅ = 35.4 × 4.3 μm, n = 20), basauxic, cylindrical, discrete, smooth-walled. Conidia 20–35 × 15–30 μm (x̅ = 28.5 × 25.6 μm, n = 20), globose to subglobose, dark brown, smooth-walled, with a truncate basal scar.
Culture characters: Ascospores germinating on WA within 24 h and germ tubes developing from the upper cell. Colonies on PDA reaching 50 mm in 1 week at 27°C, in dark, cottony, circular, with irregular edge, white from above and below, becoming dark from centre after 2 weeks. Mycelium superficial to immersed in media, with branched, septate, smooth hyphae.
GenBank numbers: ITS: MK070897, LSU: MK070898, SSU: MK070899.
Notes: This species is similar to Arthrinium garethjonesii which was introduced by Dai et al. (2016) based on morphological and phylogenetic analyses, and is only known from the southwest of China. However, A. neogarethjonesii has smaller asci (95–125 × 20–25 μm vs. 125–154 × 35–42 μm) and ascospores (25–30 × 9.5–11 μm vs. 30–42 × 11–16 μm), and the conidia are larger when compared with most Arthrinium species. Based on a Blast search using the ITS sequence in NCBI’s GenBank, the closest hits with highest similarity is A. garethjonesii (GenBank KY356086; similarity = 575/595 (97%), Gaps = 8/595 (1%)). A similar search using the LSU sequence showed highest similarity to A. garethjonesii (GenBank KY356091, similarity = 851/854 (99%), no gaps), and closest hits with A. ovatum (GenBank NG_042782; similarity = 849/875 (97%), no gaps). The phylogenetic tree generated from maximum-parsimony analysis indicated that the new species is close to A. garethjonesii and these two species cluster in two well-supported clades (MP/BYPP 100/1.00) (Hyde et al. 2020).
Arthrinium neogarethjonesii (Material examined – CHINA, Yunnan Province, Xishuangbanna Topical Botanical Garden, Bamboo Collection, on bamboo culm, 2 April 2017, Dong-Qin Dai DDQ00403, HKAS 102408, holotype). a-c Appearance of stromata on host. d Appearance of conidiomata on host. e Section of ascostroma. f Section of ascoma. g Stromatic tissue. h-j Asci. k Paraphyses. l, m Ascospores surrounded by a gelatinous sheath. n Conidia. o-r Conidia and conidiogenous cells. Scale bars: a = 1 mm, b-d = 5 µm, e = 100 µm, f-h = 50 µm, i-r = 10 µm (image from Hyde et al. 2020).
Reference:
Hyde KD, Norphanphoun C, Maharachchikumbura SSN, Bhat DJ et al. 2020 – Refined families of Sordariomycetes. Mycosphere 11, 305–1059.
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