Pleosporales » Roussoellaceae


Roussoella Sacc.

Index Fungorum number: IF4799


Saprobic on various flowering plants in terrestrial or submerged wood in freshwater habitats, mainly on bamboo and palms. Sexual morph: Ascostromata solitary to gregarious, visible as black, raised, elongate to hemispherical or dome-shaped ascostroma, uni- to multi-loculate, glabrous, coriaceous. Locules clustered, immersed under a clypeus, subglobose to lenticular or quadrilateral dome-shaped, central ostiolate, with a minute papilla. Peridium slightly thick at the side, composed of several layers of flattened, brown to dark brown pseudoparenchymatous cells, arranged in textura angularis to textura prismatica. Pseudoparaphyses dense, trabeculate, filamentous, hyaline, branching at the apex, anastomosing, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, cylindrical to cylindric-clavate, short pedicellate, with obtuse to knob-like pedicel, apically rounded with well-developed ocular chamber. Ascospores overlapping uniseriate, ellipsoidal to fusiform, pale brown to dark brown, 1-septate, ornamented, with or without a mucilaginous sheath. Asexual morph: Coelomycetous, reported as Cytoplea. Conidiomata pycnidial, scattered to clustered, solitary to gregarious, semi-immersed to superficial, globose to subglobose, dark brown to black, single- or multi-loculate, locules separated by dark, palisade-like cells. Pycnidial wall slightly thick at the base, composed of several layers of brown to dark brown, pseudoparenchymatous cells, arranged in textura angularis to textura prismatica. Conidiophore arising from the basal cavity, reduced to conidiogenous cells. Conidiogenous cell enteroblastic, phialidic, determinate, discrete, ampulliform, hyaline, smooth-walled. Conidia globose to subglobose, oblong or ellipsoidal, brown, aseptate or septate, smooth- or rough-walled. (Description form Dong et al. 2020)


Type species: Roussoella nitidula Sacc. & Paol.


Notes: Roussoella was introduced by Saccardo and Paoletti (1888) with R. nitidula as the type species. An epitype of R. nitidula was designated by Liu et al. (2014) who also found the Cytoplea asexual morph in culture. Roussoella accommodates species having large ascostromata with multi-loculate, bitunicate asci and brown, fusiform to ellipsoidal, ornamented, didymosporous ascospores which are mostly associated with bamboo and palms (Tanaka et al. 2009; Hyde et al. 2013; Liu et al. 2014; Dai et al. 2017; Jiang et al. 2019). The freshwater species Roussoella minutella (Penz. & Sacc.) Aptroot was treated as a synonym of R. pustulans (Ellis & Everh.) Y.M. Ju et al. by Hyde (1997), but not shown in Index Fungorum (2020). We follow Cai et al. (2003), using the name R. minutella. Roussoella minutella has shorter ascospores than another freshwater species R. intermedia. (Notes from Dong et al. 2020)


List of freshwater Roussoella species

Roussoella aquatica W. Dong, H. Zhang & K.D. Hyde, Fungal Divers 105: 490 (2020)

Freshwater distribution: China (Dong et al. 2020)


Roussoella intermedia Y.M. Ju, J.D. Rogers & Huhndorf, Mycotaxon 58: 447 (1996)

Freshwater distribution: North America (Fallah and Shearer 2001)


Roussoella minutella (Penz. & Sacc.) Aptroot, Nova Hedwigia 60(3–4): 367 (1995)

Basionym: Didymosphaeria minutella Penz. & Sacc., Malpighia 11(9-10): 396 (1897)

Freshwater distribution: Philippines (Cai et al. 2003)


Key to freshwater Roussoella species

1. Coelomycetous............................................................................ R. aquatica

1. Ascomycetous........................................................................................... 2

2. Ascospores 9.5–13 × 3.5–4.5 μm................................................. R. minutella

2. Ascospores 12–16 × 4–6 μm...................................................... R. intermedia



Cai L, Zhang KQ, McKenzie EHC, Hyde KD (2003) Freshwater fungi from bamboo and wood submerged in the Liput River in the Philippines. Fungal Divers 13:1–12

Dai DQ, Phookamsak R, Wijayawardene NN, Li WJ, Bhat DJ, Xu JC, Taylor JE, Hyde KD, Chukeatirote E (2017) Bambusicolous fungi. Fungal Divers 82:1–105

Dong W, Wang B, Hyde KD, McKenzie EHC, Raja HA, Tanaka K, Abdel-Wahab MA, Abdel-Aziz FA, Doilom M, Phookamsak R, Hongsanan S, Wanasinghe DN, Yu X-D, Wang G-N, Yang H, Yang J, Thambugala KM, Tian Q, Luo Z-L, Yang J-B, Miller AN, Fournier J, Boonmee S, Hu D-M, Nalumpang S, Zhang H (2020) Freshwater Dothideomycetes. Fungal Divers 105:319–575

Fallah PM, Shearer CA (2001) Freshwater ascomycetes: new or noteworthy species from north temperate lakes in Wisconsin. Mycologia 93:566–602

Hyde KD (1997) The genus Roussoëlla, including two new species from palms in Cuyabeno, Ecuador. Mycol Res 101:609–616

Hyde KD, Jones EBG, Liu JK, Ariyawansa H, Boehm E, Boonmee S, Braun U, Chomnunti P, Crous PW, Dai DQ, Diederich P, Dissanayake A, Doilom M, Doveri F, Hongsanan S, Jayawardena R, Lawrey JD, Li YM, Liu YX, Lücking R, Monkai J, Muggia L, Nelsen MP, Pang KL, Phookamsak R, Senanayake I, Shearer CA, Suetrong S, Tanaka K, Thambugala KM, Wijayawardene NN, Wikee S, Wu HX, Zhang Y, Aguirre-Hudson B, Alias SA, Aptroot A, Bahkali AH, Bezerra JL, Bhat DJ, Camporesi E, Chukeatirote E, Gueidan C, Hawksworth DL, Hirayama K, Hoog SD, Kang JC, Knudsen K, Li WJ, Li XH, Liu ZY, Mapook A, McKenzie EHC, Miller AN, Mortimer PE, Phillips AJL, Raja HA, Scheuer CH, Schumm F, Taylor JE, Tian Q, Tibpromma S, Wanasinghe DN, Wang Y, Xu JC, Yan JY, Yacharoen S, Zhang M (2013) Families of Dothideomycetes. Fungal Divers 63:1–313

Jiang HB, Hyde KD, Jayawardena RS, Doilom M, Xu J, Phookamsak R (2019) Taxonomic and phylogenetic characterizations reveal two new species and two new records of Roussoella (Roussoellaceae, Pleosporales) from Yunnan, China. Mycol Prog 18:577–591

Liu JK, Phookamsak R, Dai D, Tanaka K, Jones EBG, Xu JC, Chukeatirote E, Hyde KD (2014) Roussoellaceae, a new pleosporalean family to accommodate the genera Neoroussoella gen. nov. Roussoella and Roussoellopsis. Phytotaxa 181:1–33

Saccardo PA, Paoletti G (1888) Mycetes Malacenses. Funghi della penisola di Malacca raccolti nel 1885 dell’ Ab. Benedetto Scortechini. Atti dell´Istituto Veneto Sci 6:387–428

Tanaka K, Hirayama K, Yonezawa H, Hatakeyama S, Harada Y, Sano T, Shirouzu T, Hosoya T (2009) Molecular taxonomy of bambusicolous fungi: Tetraplosphaeriaceae, a new pleosporalean family with Tetraploa-like anamorphs. Stud Mycol 64:175–209


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