Neohelicascus unilocularis
Neohelicascus unilocularis (J. Fourn. & Y. Zhang ter) W. Dong, K.D. Hyde & H. Zhang
Index Fungorum number: IF557928; Facesoffungi number: FoF09270
Basionym: Helicascus unilocularis J. Fourn. & Y. Zhang ter, Mycol. Progr. 14(7/47): 3 (2015)
Holotype: BJFU 201081
Saprobic on submerged decaying wood from freshwater. Sexual morph: Ascostromata 200–220 μm high × 290–300 μm diam depressed-spherical, scattered, rarely in contact, immersed under a poorly developed clypeus, unilocular, ostiole discoid to ellipsoid 120–130 μm diam, barely protruding above wood surface, porate. Peridium 50–65 μm thick, pseudoparenchymatous, brown, composed of a single region of small thin-walled cells of textura angularis, outwardly turning thick-walled and dark brown, with brown prosenchymatous tissue extending into the surrounding wood; neck composed of more thick-walled and more pigmented cells forming a textura angularis to textura prismatica, clypeus 50–90 μm thick, brown in section, composed of host tissue and thick-walled melanized hyphae staining the wood surface greyish. Hamathecium 1.5–2.5 μm wide, of cellular pseudoparaphyses, ramified above asci with free ends, embedded in a gel matrix. Asci bitunicate, fissitunicate, clavate, short-pedicellate, with eight ascospores that are either obliquely uniseriate or 2–3-seriate in upper part of the ascus and uniseriate below, the spore-bearing parts 70–75 × 22–27 μm, the stipes 20–25 μm long, with endoascus coiled in the pedicel, involved in a moderate stretching upon dehiscence, with apical ocular chamber visible on immature asci. Ascospores (21.6) 23.0–25.8 (27.3) × (9.2) 10.2–11.4 (11.7) μm, Q= (2.0) 2.1–2.4 (2.8); n = 66 (Me = 24.3× 10.8 μm; Qe = 2.3), ellipsoid-fusiform with broadly rounded ends, inequilateral, 1-euseptate, septum median to slightly submedian (Qc = 0.5–0.56, n = 30), slightly constricted at the septum, the upper cell slightly broader than the lower one, with 2–4 large refractive guttules, wall smooth, pale olivaceous brown, lacking sheath or appendages. Asexual morph: Undetermined.
Culture characteristics: Ascospores germinating on MEA after 1–2 d; colony radius at 26–28 °C on MEA 13–15 mm after two weeks, 18–20 mm after four weeks. Colony irregularly circular, first pale grey, surface covered with a thin layer of off-white aerial hyphae slightly extending over the margin, turning blackish in the center with white margin at 10 days, then the margin turns grey after two weeks, composed of hyaline to pale brown, sparsely septate smooth hyphae, up to 3.5 μm wide; reverse reddish to blackish; odour not detected.
Material examined: FRENCH WEST INDIES, MARTINIQUE: Prêcheur, Anse Couleuvre, coastal rainforest, Couleuvre River, on submerged wood along with Helicascus thalassioideus, 3 June 2014, J. Fournier, M.J.F. 14020 (BJFU 201081); same location and date, on submerged wood, J. Fournier, M.J.F. 14020-1 (Paratype, BJFU 201083).
Notes: Phylogenetic analysis of combined LSU, SSU, ITS and TEF sequence data indicated that the two strains of N. unilocularis form a well-supported clade sister to other species of Neohelicascus (Dong et al. 2020).
Freshwater distribution: France (Zhang et al. 2015)
Fig. 1 Helicascus unilocularis M.J.F. 14020. A Ascostromata on host surface; B Close-up on a porate ostiole; C Ascostromata in vertical section; D Section of upper part of the peridium with reddish brown pseudostromatic tissue; E Ascostroma in vertical section showing the peridium, the ostiolar neck and the
pseudostromatic tissue; F Peridium at side (D-F mounted in chloral-lactophenol). Scale bars: A=0.5 mm; B, C=0.2 mm; D, F=20 μm; E=50 μm
(Retrieved from https://www.researchgate.net/publication/279189081_Helicascus_unilocularis_sp_nov_a_new_freshwater_pleosporalean_ascomycete_from_the_Caribbean_area_Jiaqi_Zhang_Yupei_Zhou_Zhipeng_Dou_Jacques_Fournier_Ying_Zhang_2015_Mycological_Progress_14_47)
Fig. 2 Helicascus unilocularis M.J.F. 14020. G Mature asci with hamathecium, in blue-black Waterman ink; H Immature ascus showing the coiled endoascus at base; I Stretching of the basal endoascus upon dehiscence of the ascus (H-I in chlorazol black); J, K Pseudoparaphyses showing the free enlarged tips (in chlorazol black); L Ascospores in India ink, showing the absence of sheath or appendages. Scale bars: G=
20 μm; H–L=10 μm
(Retrieved from https://www.researchgate.net/publication/279189081_Helicascus_unilocularis_sp_nov_a_new_freshwater_pleosporalean_ascomycete_from_the_Caribbean_area_Jiaqi_Zhang_Yupei_Zhou_Zhipeng_Dou_Jacques_Fournier_Ying_Zhang_2015_Mycological_Progress_14_47)
References
Zhang JQ, Zhou YP, Dou ZP, Fournier J, Zhang Y (2015) Helicascus unilocularis sp. nov., a new freshwater pleosporalean ascomycete from the Caribbean area. Mycol Prog 14:1–8
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