Diplodia magnoliigena
Diplodia magnoliigena Jayasiri, E.B.G. Jones & K.D. Hyde, sp. nov.
Index Fungorum number: IF555579; Facesoffungi number: FoF05291
Holotype – MFLU 18–2214
Etymology – Referring to the host genus on which the fungus was collected, Magnolia (Magnoliaceae).
Saprobic on cone of Magnolia grandiflora. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 190–210 μm high × 182–212 μm diam. ( av. = 205 × 198 μm; n = 10), solitary, partly immersed, partially erumpent when mature, dark brown to black, more or less globose, with wall composed of two layers; an outer layer of dark brown, thick-walled cells of textura angularis and an inner layer of thin-walled hyaline cells. Ostiole 55–65 μm high (av. = 62 μm; n = 10), central, circular, papillate. Conidiophores absent. Conidiogenous cells 9–15 × 2–3 μm (av. = 13 × 2.5 μm; n = 20), holoblastic, integrated, annellidic, hyaline, cylindrical, smooth, indeterminate, proliferating percurrently to form one or two indistinct annellations. Conidia 26–30 × 12–14 μm (av. = 28 × 12.5 μm; n = 30), hyaline and aseptate at first, becoming dark brown and 1- septate, oblong to ovoid, straight, both ends broadly rounded, smooth, thick-walled.
Culture characters – Conidia germinated on MEA within 24 hr. Colonies growing on MEA reaching 40 mm diam. after 2 weeks at 18oC, with fluffy mycelium, initially white to amber in the centre, after two weeks turning dark amber, white to dark amber, olivaceous with age; reverse submerged mycelium, first yellow, with age dark amber, almost olivaceous, and with age olivaceous center.
Material examined – CHINA, Yunnan Province, Kunming Institute, on fallen cone of Magnolia grandiflora (Magnoliaceae), 15 May 2018, S.C. Jayasiri, C 458 (MFLU 18–2214, holotype), ex-type living culture MFLUCC 18–1554, KUMCC 18–0236.
GenBank numbers – SSU: MK347915, ITS: MK347807, LSU: MK348026, tub2: MK412873
Notes – Diplodia magnoliigena groups sister to D. mutila and Diplodia pyri with high support (Fig. 112) but differs morphologically (Fig. 113) from the latter by having dark brown, 1- septate, longer conidia and the conidiomatal wall consists of two layers. Diplodia mutila is characterized by short conidia, which are rarely pale brown, and a three-layered peridium (Phillips et al. 2013). In addition, these two species can be distinguished by 13 (4.1) and 7 (1.8%) base pair differences in tef1 and tub2 gene regions respectively. Confirmed hosts for the D. mutila are Chamaecyparis lawsoniana, Fraxinus, Malus, Populus, Taxus baccata and Vitis vinifera (Phillips et al. 2013) together with a recent record on Juglans regia (Díaz et al. 2018).
Figure 113 – Diplodia magnoliigena (MFLU 18–2214, holotype). a Host cone. b, c Conidiomata on host surface. d Section through conidioma. e Conidioma wall. f–h Conidiogenous cells. i–m Conidia. Scale bars: a = 1 cm, b, c = 200 μm, d = 100 μm, e–h, k–m = 20 μm, i, j = 10 μm.