Roussoellaceae J.K. Liu, Phookamsak, D.Q. Dai & K.D. Hyde, in Liu et al., Phytotaxa 181(1): 7 (2014).
MycoBank number: MB 804651; Index Fungorum number: IF 804651; Facesoffungi number: FoF 08360, 73 species.
Saprobic on various hosts especially bamboo and palms or human pathogen. Sexual morph: Ascostromata solitary or gregarious, visible as raised, black, shiny to dull, rounded, dome-shaped to elongated linear, occasionally covered by black, dirt elements, sparse on host surface, immersed to semi-immersed, uni- to multi-loculate, glabrous ostiolate, papillate. Locules immersed in a clypeus, or erumpent through host tissue by black protruding papilla, subglobose to ampulliform, or dome- shaped to wedge-shaped, or quadrilateral, with a flattened base, ostiole individually central, with intra-epidermal papilla, or somewhat erumpent through host tissue. Ascomata immersed to semi- immersed, solitary to gregarious, globose to subglobose, or ampulliform, glabrous to setose. Peridium composed of several layers of brown to dark brown pseudoparenchymatous cells, intermixed with the host tissue, arranged in textura angularis to textura prismatica. Hamathecium comprising dense, filiform, septate, branched, anastomosed, narrowly cellular pseudoparaphyses, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, cylindrical to cylindric-clavate, or clavate, pedicellate, apically rounded, with well-developed ocular chamber. Ascospores overlapping 1–2-seriate, ellipsoidal to fusiform, septate, hyaline or brown to dark brown, constricted at the septum, smooth- to rough-walled, with poroid, reticulate, echinulate or striated ornamentation, surrounded by a wide mucilaginous sheath. Asexual morph: Coelomycetous, cytoplea-like, melanconiopsis-like, neomelanconium-like or cyclothyrium-like. Conidiomata pycnidial, stromatic, immersed under a clypeus to erumpent through host epidermis by minute papilla, globose to subglobose, or dome-shaped, dark brown to black, uni- to multi-loculate; locules separated by vertical columns of dark pigmented pseudoparenchyma. Pycnidial walls comprising several layers of brown to dark brown pseudoparenchymatous cells, arranged textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, annellidic, discrete, hyaline, cylindrical to ampulliform, or doliform, unbranched, aseptate or septate, smooth, arising from the inner cavity of conidioma. Conidia globose, oblong or ellipsoidal, base obtuse to truncate, narrower towards the apex, hyaline to brown or dark brown, aseptate or septate, smooth- to rough-walled, with minutely warty, or verrucose.
Type – Roussoella Sacc.
Notes – Roussoellaceae was introduced by Liu et al. (2014) and is typified by Roussoella with R. nitidula as the type species. The family was introduced to the Pleosporales, accommodating ascomycetous taxa having raised, black, dome-shaped to elongated linear ascostromata, with uni- to multi-loculate, immersed in a clypeus, cylindrical to clavate, bitunicate asci, with brown, 2-celled ornamented ascospores and forming coelomycetous asexual morph (Liu et al. 2014). Three genera were accommodated in this family viz. Neoroussoella, Roussoella and Roussoellopsis (Liu et al. 2014, Dai et al. 2017). Ariyawansa et al. (2015a) introduced a monotypic genus Elongatopedicellata in Roussoellaceae. Jaklitsch & Voglmayr (2016) treated Roussoellaceae as a synonym of Thyridariaceae based on their phylogenetic results of a combined ITS, LSU, rpb-2, SSU and tef1 data matrix. However, the familial statement of Roussoellaceae is debatable due to the differences of morphological features coupled with multi-gene phylogeny (Tibpromma et al. 2017, Wanasinghe et al. 2018c, Jayasiri et al. 2019, Jiang et al. 2019, Karunarathna et al. 2019, Phookamsak et al. 2019). Wanasinghe et al. (2018c) introduced two novel genera, Pararoussoella and Pseudoneoconiothyrium to accommodate roussoella-like taxa in Thyridariaceae. However, Phookamsak et al. (2019) transferred these two genera to Roussoellaceae based on multi-gene phylogenetic analyses coupled with morphological characteristics. Mapook et al. (2020) introduced three more genera viz. Pseudoroussoella, Setoarthopyrenia and Xenoroussoella in Roussoellaceae. Based on morphological characteristics, Ariyawansa et al. (2014b) treated Appendispora in Roussoellaceae whereas Hyde et al. (2017) and Doilom et al. (2018) also treated Immotthia in Roussoellaceae. The coelomycetous genus Cytoplea has been reported as the asexual morph of Roussoella, however, there is no proven for the link between these two genera (Hyde et al. 1996, Liu et al. 2014). Therefore, Wijayawadene et al. (2014b) treated Cytoplea as a separated genus and accommodated Cytoplea in Roussoellaceae. Presently, 12 genera are accommodated in this family (Wijayawadene 2018, 2020, Phookamsak et al. 2019, Mapook et al. 2020).