Mycosphaerellales » Mycosphaerellaceae » Exosporium

Exosporium tiliae

Exosporium tiliae Link, Mag. Gesell. naturf. Freunde, Berlin 3(1-2): 10 (1809).

            Index Fungorum number: IF 8240; Facesoffungi number: FoF 11150 , Fig. 1, 2

Description: see Videira et al. (2017), Voglmayr and Jaklitsch (2017).

Saprobic on host. Sexual morph: Unknown. Asexual morph: Pseudostromata 147–150 μm diam., 140–145 μm high, superficial to semi-immersed, well developed, dark brown to black, pseudoparenchymatous, margin comprises dark brown, verrucose simple hyphae. Conidiomata 145–150 μm diam., 135–145 μm high, immersed in pseudostromata, singly or small groups, globose to depressed globose, often strongly depressed, dark brown to black. Mycelium immersed, growing in conidiomata below the periderm, on the surface of the host substrate forming stroma-like masses of light to dark brown pseudoparenchymatous cells. Conidiophores 80−125 × 11−15 µm (x̄ = 85.3 × 12.3 µm, n = 20), somewhat swollen apex, fasciculate, arising from the upper cells of the stromata, straight or flexuous, cylindrical, finely verrucose, brown to dark brown, slightly darkly pigmented at the apex, 3–8-septate. Conidia 86−130 × 11−14 µm (x̄ = 92 × 12.6 µm, n = 20), straight or curved, obclavate to rostrate, smooth-walled, pale to golden brown or dark brown at maturity, darkly pigmented at the apex, 3–8-septate.

Material examined: The United States, Ohio, Erie, Birmingham, 41.330049 -82.360719, on Tilia Americana (Malvaceae), 16 March 1907, A.M. Starr (CUP-020505).

Fig. 1 Exosporium tiliae (CUP-020505, asexual morph). a–d Herbarium material. e–p Conidiophores and conidia. Scale bars: c = 2000 μm, d = 100 μm, e–p = 20 μm.

 

Fig. 2 Exosporium tiliae (= Helminthosporium tiliae, re-drawn from Fig. 16 in Voglmayr and Jaklitsch 2017). a Ostioles in face view. b Ascomata in vertical section. c Section of peridium. d Pseudoparaphyses. e Asci. f Ascospores. g, h Conidiophores. Scale bars: a = 200 μm, b = 100 μm, c, e = 20 μm, d, f–h = 10 μm.

 

Importance and distribution

Exosporium comprises 42 species known on a wide range host plants including Acrocomia aculeata (Arecaceae), Albizia falcataria (Fabaceae), Bauhinia purpurea (Fabaceae), Bernardia dichotoma (Euphorbiaceae), Bryophyllum calycinum (Crassulaceae), Funtumia sp. (Apocynaceae), Juniperus sp. (Cupressaceae), Phyllostachys edulis (Poaceae), Pothomorphe umbellata (Piperaceae), Rauvolfia sp. (Apocynaceae), Semiarundinaria yashadake (Poaceae) and Theobroma cacao (Malvaceae). Exosporium has a wide distribution occurring in Asia (India, Japan, Philippines), North America (Caribbean, the United States) and Oceania (Papua New Guinea). Molecular data is required for further species delimitation.

 

References

 

Crous PW, Summerell BA, Shivas RG, Romberg M, Mel'nik VA, Verkley GJ, Groenewald JZ. 2011 – Fungal Planet description sheets: 92–106. Persoonia 27, 130–162. https://doi.org/10.3767/003158511X617561

Ellis MB. 1960 – Dematiaceous hyphomycetes 1. Mycological Papers 76, 1–36. https://biotanz.landcareresearch.co.nz/references/1cb0e2bb-36b9-11d5-9548-00d0592d548c

Fries EM. 1832 – Systema Mycologicum 3, Moritz, 524 p.

Link HF. 1809 – Observationes in ordines plantarum naturales. Dissertatio I Mag Ges naturf Fr Berl 3, 3–42. https://cir.nii.ac.jp/crid/1573387450599556992

Videira SIR, Groenewald JZ, Nakashima C, Braun U, Barreto RW, de Wit PJGM, Crous PW. 2017 – Mycosphaerellaceae - Chaos or clarity? Studies in Mycology 87, 257–421. https://doi.org/10.1016/j.simyco.2017.09.003

Voglmayr H, Jaklitsch W. 2017 – Corynespora, Exosporium and Helminthosporium revisited – New species and generic reclassification. Studies in Mycology, 43–76. https://doi.org/10.1016/j.simyco.2017.05.001

 

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