Lasiodiplodia hyalina Z. P. Dou, Y. Zhang, sp. nov, Mycobank Number: MB 817651
Etymology : from the Latin “hyaline”, in reference to the hyaline conidia.
Sexual morph: unknown. Asexual morph: Conidiomata stromatic, produced on pine needles on SNA within 1–2 wk, solitary, immersed or semi-immersed, iron grey to black, covered with dense mycelium, mostly uniloculate, 255–500 μm diam, solitary, globose, thick-walled, with a central ostiole. Paraphyses hyaline, cylindrical, thin-walled, initially aseptate, becoming up to 1–7 septate when mature, sometimes branched or connected to the ladder shaped or H form, rounded at apex, occasionally basal or apical cells swollen, 24–82 × 3–7 μm. Conidiophores absent. Conidiogenous cells holoblastic, discrete, hyaline, smooth, thin-walled, cylindrical to ampulliform, proliferating percurrently, (8–)9–18(–20) × 4–7 μm (av. = 12.6 × 5.3 μm, n = 60). Conidia initially hyaline, aseptate, ellipsoid to ovoid, occasionally with a median or submedian constriction, including granular content, both ends broadly rounded, thick-walled, verruculose, (19–)20–27(–28) × 12–16 μm (av. of 30 conidia = 24 × 13.6 μm, L/W ratio = 1.77, range from 1.36 to 2.00), a few conidia turning pale brown with a single median septum and longitudinal striations after three months, but most conidia remain hyaline.
Culture characteristics : Colonies on MEA initially white with woolly aerial mycelia, becoming iron grey to black on the surface after 2 weeks; reverse side of the colonies olivaceousgrey to dark black. Colonies reaching 76.5 mm on MEA after 48 h in the dark at 28 °C.
Specimens examined : CHINA, Hainan Province, Danzhou City, the Danzhou Tropical Botanical Garden, from cankered stems of Acacia confusa Merr., 3 November 2015, Y. Zhang & Y. P. Zhou (HMAS 255216, holotype), ex-type living culture, CGMCC 3.17975; Guangdong Province, Guangzhou City, Sculpture Park, from cankered branches of an unidentified woody plant, 21 January 2016, Z.P. Dou & Z.C. Liu (CGMCC 3.18383).
Note : The conidia of L. hyalina keep hyaline until three months’ growing on SNA, then only a small proportion (ca. 10%) of conidia become pigmented with striations on the surface, which looks senescent. Phylogenetically, L. hyalina is closely related to L. thailandica and L. iraniensis (Fig.1). The tef1-α region of L. hyalina is distinguishable from those of L. thailandica (CPC 22795, GenBank Accession No. KJ193681) and L. iraniensis (IRAN 1520C, GenBank Accession No. GU945336) with identity of 97.0% and 97.1%, respectively. In addition, the larger conidiogenous cells ((8–)9–18(–20) × 4–7 μm vs 8–9 × 2–4 μm) and broader (3–7 μm vs 1–1.5 μm), branching and anastomosing paraphyses of L. hyalina are distinguishable from those of L. thailandica (Trakunyingcharoen et al. 2015). The smaller conidiomata (255–500 μm vs up to 980 μm) and shorter paraphyses (24–82 μm vs up to 127 μm) of L. hyalina differs from those of L. iraniensis (Abdollahzadeh et al. 2010). Furthermore, some hyaline conidia of L. hyalina show a median or submedian constriction (Fig.2), which also distinguishes it from the other two species.
FIG 2. Lasiodiplodia hyalina (From holotype, CGMCC 3.17975) A Conidiomata formed on pine needles in culture; B The ladder shaped paraphyses; C–F Conidia developing on conidiogenous cells between paraphyses; G Mature, 1-septate conidia with longitudinal striations; H, I Hyalineconidia. Scale bars: a = 1mm; b–i = 10 µm