Helotiales » Chaetomellaceae » Pilidium

Pilidium concavum

Pilidium concavum (Desm.) Höhn., Sber. Akad. Wiss. Wien, Math.-naturw. Kl., Abt. 1 124: 148 (1915)

Index Fungorum number: IF228448         Facesoffungi number: FoF05212

 

Basionym: Ceuthospora concava Desm., Annls Sci. Nat., Bot., sér. 3 8: 17 (1847)

 

Sexual morph: Undetermined. Asexual morph: Conidiomata sporodochial, 175–200 µm high (x̄ = 185 µm, n = 10), 122–140 µm diam. (x̄ = 133.5 µm, n = 10), 48–56.5 µm (x̄ = 52.5 µm, n = 5) wide at the base, superficial, scattered, sessile, relatively sphaerical, initially yellowish brown, turning brownish or almost black, initially convex cap turning to concave. Peridium thick, textura angularis. Conidiophores 11.2–19.8 × 1.0–1.4 µm (x̄ = 15.6 × 1.2 µm, n = 10), a dense palisade, hyaline to pale brown, tapering distally. Conidiogenous cells 2.2–3.3 × 0.8–1.1 µm (x̄ = 2.6 × 0.9 µm, n = 10), enteroblastic, phialidic, hyaline, tapering towards the apex, terminal and lateral. Conidia 4.8–7.4 × 1.5–2.4 µm (x̄ = 6.1 × 1.9 µm, n = 40), L/W 3.2, 1-celled, hyaline, fusoid to allantoid, slightly falcate, apex acute, base obtuse, thin-walled, guttules at both ends, formed singly on the conidiogenous cells.

 

Culture characteristics: Colonies reaching to 36.5 mm after 2 weeks at 28 °C on PDA with two zones. Inner zone dirty yellow to light brown, flat, slightly clock wise rotate sparse mycelia, reverse light brown; outer layer dirty white, flat, smooth, lobate margin, reverse dirty white. Later, zonate, dirty white, flat surface, smooth with light brown patches, reverse dark brown centre and light brown margin.

 

Host and Habitat: Saprobic or Pathogenic on Bergenia crassifolia, Eucalyptus sp., Fallopia japonica, Fragaria ananassa, Fragaria × ananassa, Olea europaea, Paeonia suffruticosa, Pelargonium sp., Picea sp., Potentilla reptans, Quercus agrifolia, Q. coccifera, Quercus sp., Rosa sp., Vitis sp., Vitis vinifera and decaying leaves (Farr and Rossman 2021).

 

Known distribution: Belgium, Brazil, China, Cuba, France, Greece, Iran, Italy, Japan, Poland, Portugal, South Korea, Thailand, Ukraine, United Kingdom and United States (California, South Carolina) (Farr and Rossman 2021).

 

Material examined: THAILAND, Muang, Mueang, Chiang Rai District, Chiang Rai 57100, (20° 03′ 24.7′′ N, 99° 52′ 23.5′′ E), dead petals and leaves of Rosa sp. (Rosaceae), 20 August 2017, M.C. Samarakoon, SAMC017 (MFLU 18-0106, HKAS 102341), living culture MFLUCC 17-2671.

 

GenBank Accession No: ITS: MK100327, LSU: MK108192, SSU: MK108189.

 

Figure X. Pilidium concavum (MFLU 18-0106, new geographical record). a Host. b, c Appearance of conidiomata on host surface. d Vertical section through the conidioma. e–h Conidiophores and conidiogenous cells. i, j Culture on PDA (i from above view, j from below view). k Conidiospores. Scale bars: b–d = 100 µm, e–h, k = 5 µm.

Notes: Pilidium concavum (synanamorph Hainesia lythri (Desm.) Höhn.; sexual morph Discohainesia oenotherae (Cooke & Ellis) Nannf.), is an interesting species with morphological differentiation due to genetic control (Sutton 1980; Palm 1991; Rossman et al. 2004). The species is often pathogenic and occasionally saprobic on flowers, fruits and oil and forest plants (Cardin et al. 2009; Geng et al. 2012; Lopes et al. 2010; Ayoubi et al. 2016). Pilidium concavum has been recorded mainly in temperate regions and on many hosts. Palm (1991) reports P. concavum on Rosa leaves from the United Kingdom and Connecticut (USA). The strain isolated from petals and leaves of Rosa sp. in this study is similar in morphology and phylogeny to P. concavum. The ITS-LSU phylogenetic studies reveal that strain MFLUCC 17-2671 is closely related to P. concavum and P. lythri clade (Hyde et al. 2019). Morphological characterizations, especially the conidia, overlap with the consistency measurements (5.5–7.2 × 1.4–1.8 µm) described by Palm (1991). Thus, we report this collection as P. concavum on petals and leaves of Rosa sp. as a saprobe from Thailand, a new geographical record.

 

Reference:

1. Ayoubi N, Soleimani MJ, Zare R (2016) Pilidium concavum, causing tan-brown rot on strawberry in Iran. J Plant Pathol 98: 667–669.

2. Cardin L, Vincenot L, Balesdent MH (2009) First Report of Pilidium concavum on Bergenia crassifolia in France. Plant Dis 93(5): 548

3. Farr DF, Rossman AY (2021) Fungal Databases, U.S. National Fungus Collections, ARS, USDA. https://nt.ars-grin.gov/fungaldatabases/

4. Geng WL, Hu P, Ma Z, Zhao XY, Wei YM (2012) First report of Pilidium concavum causing tan-brown leaf spot on strawberry in China. Plant Dis 96:1377

5. Hyde KD, Tennakoon DS, Jeewon R, Bhat DJ et al. (2019) Fungal diversity notes 1036–1150: taxonomic and phylogenetic contributions on genera and species of fungal taxa. Fungal Divers. 96: 1–242.

6. Lopes UP, Zambolim L, Lopes UN, Pereira OL, Costa H (2010) First report of Pilidium concavum causing tan-brown rot in strawberry fruits in Brazil. Plant Pathol 59: 1171–1172.

7. Palm ME (1991) Taxonomy and morphology of the synanamorphs Pilidium concavum and Hainesia lythri (coelomycetes). Mycologia 83:787–796.

8. Rossman AY, Aime MC, Farr DF, Castlebury LA, et al. (2004) Thecoelomycetous genera Chaetomella and Pilidium represent a newly discovered lineage of inoperculate discomycetes. Mycol Prog 3: 275–290.

9. Sutton BC (1980) The Coelomycetes. Fungi imperfecti with pycnidia, acervuli and stromata. Ann Mycol 6: 484.

 

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