Leucaenicola osmanthi Ariyawansa, I. Tsai & Thambugala, 2020

Ariyawansa, Hiran A., Tsai, Ichen, Hozzein, Wael N. & Thambugala, Kasun M., 2020, Leucaenicola osmanthi sp. nov. (Bambusicolaceae, Pleosporales), causing leaf spot of Osmanthus fragrans in Taiwan, Phytotaxa 437 (1), pp. 23-31 : 28

Leucaenicola osmanthi Ariyawansa, I. Tsai & Thambugala sp. nov. FIGURE 2 .

MycoBank number: MB833892

Type: — TAIWAN. Taipei City, Nangang District, Nangang Tea Processing Demonstration Center ( N: 25°07′10′′, E: 121°61′21′′), on leaves of Osmanthus fragrans ( Oleaceae ), 24 March 2018, Tsai Ichen, holotype NTUH 18-101-1, ex-holotype NTUCC 18-101-1.

Associated with leaf lesions of Osmanthus fragrans . Leaf lesions expanded, developing from apex to middle of leaves. Sexual morph: undetermined. Asexual morph: Conidiomata 125–215 × 280–390 μm (x̅ = 172.7 × 331.3 μm), pycnidial, solitary, scattered, immersed to slightly erumpent through the host tissues, uni-loculate, globose to subglobose. Conidiomatal wall comprising few layers of brown to lightly-pigmented, thick-walled, cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–11 × 2–4 μm (x̅ ± SD = 8.5 ± 1.6 × 3.4 ± 0.5 μm), holoblastic, hyaline, smooth, ampulliform to doliiform or cylindrical, lining the conidiomatal cavity. Conidia 3–4 × 2–3 μm (x̅ ± SD = 3.5 ± 0.2 × 2.3 ± 0.1 μm), ellipsoidal to cylindrical, initially hyaline, becoming pale brown, thinwalled, smooth, aseptate, with 1–2 guttules.

Etymology: —The species epithet “osmanthi ” refers to the host genus on which the fungus was collected.

Additional material examined: — TAIWAN. Taipei City, Nangang District, Nangang Tea Processing Demonstration Center (N: 25°07′10′′, E: 121°61′21′′), on leaves of Osmanthus fragrans ( Oleaceae ), 24 March 2018, Ariyawansa H. A., NG14-2 (NTUH 18-101-2), ex-type culture (NTUCC 18-101-2); ibid. 25 April 2018, Ariyawansa H. A., NG14-3 (NTUH 18-101-3), ex-type culture (NTUCC 18-101-3).

Notes: Morphologically and phylogenically, Leucaenicola osmanthi is a unique taxon ( FIGURES 1 and 2 ). Leucaenicola osmanthi varies from the generic type; Leucaenicola aseptata by relatively larger conidiomata (125–215 × 280–390 μm versus 80–100 × 100–125 μm), larger conidiogenous cells (5–11 × 2–4 μm versus 2.5–3 × 1.5–2 μm), larger conidia (3–4 × 2–3 μm versus 3–4 × 1.5–2 μm), host ( Osmanthus versus Leucaena ), pathogenicity (pathogenic versus saprobic) and distribution ( Taiwan versus Thailand). Our new species diverges from its phylogenetically closely related species, Leucaenicola phraeana by larger conidiomata (125–215 × 280–390 μm versus 90–115 × 130–150 μm), larger conidiogenous cells (5–11 × 2–4 μm versus 3–4 × 1.5–2 μm), relatively larger conidia (3–4 × 2–3 μm versus 3–4 × 1.5–2 μm), host ( Osmanthus versus Leucaena ), pathogenicity (pathogenic versus saprobic) and distribution ( Taiwan versus Thailand).

Figures

FIGURE 1. RAxML tree obtained from the concatenated DNA sequence data of ITS, LSU, SSU, rpb2 and tef1 genes.The new isolates are shown in red. ML bootstrap values (BS) ≥70 % and Bayesian posterior probabilities (PP) ≥ 0.95 are presented at the nodes. The branches Leucaenicola clades were scaled to half to allow an enhanced arrangement of the tree. The scale bar presents the number of estimated substitutions per site. Sulcatispora acerina (CBS 139703) and Sulcatispora berchemiae (CBS 139704) (Sulcatisporaceae, Pleosporales) were used as outgroups for rooting the tree.

FIGURE. 2. Leucaenicola osmanthi (NTUH 18-101-1, holotype). a, b.Appearance of Conidiomata on host surface. c. Cultures on PDA, from above and below. d. Vertical section through conidioma. e. Conidiomatal wall. f. Conidiogenous cells and developing conidia. g. Conidia. Scale bars: d = 40 µm, e = 10 µm f–g = 5 µm.