Pleosporales » Didymellaceae

Didymella

Didymella Sacc., Michelia 2(no. 6): 57 (1880)

= Ascochytula (Potebnia) Died., Annls mycol. 10(2): 141 (1912)

= Chaetodiplodia P. Karst., Hedwigia 23(4): 62 (1884)

= Dothisphaeropsis Höhn., Hedwigia 60: 195 (1918)

= Microsphaeropsis Syd. & P. Syd., Annls mycol. 14(5): 369 (1916)

= Peyronellaea Goid., Annali Sper. agr., N.S. 6: 92 (1952)

= Polyopeus A.S. Horne, J. Bot., Lond. 58: 239 (1920)

Other possible synonym are Amerodothis, Chaetosphaeropsis, Haplotheciella. etc.

Index Fungorum, Facesoffungi number: FoF 16550, MycoBank, GenBank

Fig 1

Classification: Didymellaceae, Pleosporales, Dothideomycetes, Ascomycota, Fungi

Saprobic and or pathogenic on host plants. The sexual morph is characterised by ascomata which are immersed or erumpent, scattered or gregarious, (sub-)globose to flattened, and ostiolate. The peridium is constituted by cells of textura angularis. Asci are 8-spored, cylindrical to clavate or saccate, and bitunicate. Ascospores are hyaline or brown, ellipsoidal to cymbiform, aseptate to several septa, and constricted at the septum (Chen et al. 2022). The asexual morph is characterised by immersed to semi-immersed pycnidial conidiomata, which are dark brown to black, unilocular, glabrous, globose to subglobose, or irregular in shape, ostiolate or poroid, and sometimes with elongated necks. The ostiole is single or multi-ostiolate, and located in the center. The pycnidial wall is comprised of textura angularis, thick-walled and dark brown to hyaline cells. Conidiophores are reduced to conidiogenous cells. Conidiogenous cells are enteroblastic and phialidic, determinate, doliiform to ampulliform, hyaline and smooth-walled. Conidia are hyaline or pale brown, 0–1-septate, smooth and thin-walled, guttulate, variable in shape, i.e. ellipsoidal to subglobose, cylindrical to subcylindrical, fusiform, oblong, ovoid, sometimes allantoid (Saccardo 1880, Li et al. 2020).

Type species: Didymella exigua (Niessl) Sacc., Syll. fung. (Abellini) 1: 553 (1882)

= Didymosphaeria exigua Niessl, Oesterr. bot. Z. 25(4): 165 (1875)

= Didymella nemoralis (Sacc.) Sacc., Syll. fung. (Abellini) 1: 552 (1882)

= Didymella media (Sacc.) Sacc., Syll. fung. (Abellini) 1: 553 (1882)

Notes: Didymella was introduced by Saccardo (1880) based on D. exigua as the type species in Mycosphaerellaceae, and subsequently placed in Pleosporaceae, Phaeosphaeriaceae, Venturiaceae, and Pleosporales genera incertae sedis (De Gruyter et al. 2009, Chen et al. 2022). Based on LSU and SSU sequence data, De Gruyter et al. (2009) introduced it to a new family Didymellaceae with Didymella as the type genus, which comprises Ascochyta, Didymella, Phoma, and several related phoma-like genera. Aveskamp et al. (2010) and Chen et al. (2015) revised the taxonomy of Didymellaceae and clarified the delimitation of Ascochyta, Didymella and Phoma based on LSU, ITS, rpb2 and tub2 sequence data. Morphologically, Didymella species vary and sometimes overlap, therefore DNA sequences are necessary for accurate species identification. Currently, there are 300 species listed in Didymella in Species Fungorum (September 2024). There are more than seventy thousand sequence data available for Didymella in GenBank (September 2024). The updated taxonomic treatment of this genus is Didymellaceae, in Pleosporales (Dothideomycetes) (Wijayawardene et al. 2022, Hyde et al. 2024).

For all accepted species: see Species Fungorum, and search Didymella.

Figure 1 – a–b Didymella exigua c–t Didymella macrostoma (MFLU 15-1344) a Asci. b Ascospores. c Herbarium package and specimens. d Appearance of black coniodiomata on the host. e Surface view of conidioma. f, g Vertical section of conidiomata. h Section of peridium. i–k Conidiogenous cells and developing conidia. l–t Conidia. Scale bars: a–b, h = 10 µm, e–g = 100 µm, i–t = 5 µm. (a–c Redrawn from Chen et al. (2022) by Chao Chen, c–t Originally published in Li et al. (2020) and republished with authority)

 

References

Aveskamp MM, de Gruyter J, Woudenberg JHC, Verkley GJM et al. 2010 – Highlights of the Didymellaceae: a polyphasic approach to characterise Phoma and related pleosporalean genera. Studies in Mycology 65, 1–60.

Chen Q, Jiang JR, Zhang GZ, Cai L et al. 2015 – Resolving the Phoma enigma. Studies in Mycology 82, 137–217.

Chen Q, Bakhshi M, Balci Y, Broders KD et al. 2022 – Genera of phytopathogenic fungi: GOPHY 4. Studies in Mycology 101, 417–564.

De Gruyter J, Aveskamp MM, Woudenberg JHC, Verkley GJM et al. 2009 –Molecular phylogeny of Phoma and allied anamorph genera: Towards a reclassification of the Phoma complex. Mycological research 113, 508–519.

Hyde KD, Noordeloos MT, Thiyagaraja V, He MQ et al. 2024 – The 2024 Outline of Fungi and fungus-like taxa. Mycosphere 15(1), 5146–6239.

Li WJ, McKenzie EH, Liu JK, Bhat DJ et al. 2020 – Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100, 279–801.

Saccardo PA. 1880 – Fungi Gallici lecti a cl. viris P. Brunaud, Abb. Letendre, A. Malbranche, J. Therry, vel editi in Mycotheca Gallica C. Roumeguèri. Series II. Michelia 2(6), 39–135.

Wijayawardene NN, Hyde KD, Dai DQ, Sánchez-García ML et al. 2022 – Outline of Fungi and fungus-like taxa–2021. Mycosphere 13(1), 53–453.

 

Entry by Chao Chen^1,2,3

Edited by Kevin D. Hyde^1,3 & Ishara S. Manawasinghe¹

 

¹Innovative Institute for Plant Health, College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, Guangdong, P.R. China.

²Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand.

³Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, Thailand; School of Science, Mae Fah Luang University, Chiang Rai, Thailand.

 

Published online 2024-December 30.

 

 

 

 

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