Fungalpedia – Note 3042, Xyloma
Xyloma Pers., Neues Mag. Bot. 1: 85 (1794).
Citation when using this data: Wang QT et al. 2023 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank.
Classification: Rhytismataceae, Rhytismatales, Leotiomycetidae, Leotiomycetes, Pezizomycotina, Ascomycota, Fungi.
Xyloma is accepted here for species from the Salix clade (Fig. 1; Wang QT et al. 2023, Supplementary Figs. 1-3).
Parasitic on Salix spp. Stromata developing on the adaxial surfaces or amphigenously on living leaves or young twigs, unilocular, occasionally confluent, roughly circular, oblong or irregular. Lips absent. Ascomata mature on dead or living leaves or young twigs, opening by several interconnected, irregular or circular splits. Paraphyses filiform, more or less swollen at the apex, with thin gelatinous sheaths. Ascospores filiform, clavate or ellipsoidal, with thin gelatinous sheaths.
Notes: The genus Xyloma was established by Persoon (1794) and lectotypified with Xyloma salicinum by Höhnel (1917a, b). Persoon also included X. acerinum Pers. in the original publication, thus technically the genus Rhytisma Fr. (1819) becomes a later synonym that takes precedence due to the sanctioning regulations. However, it is not clear from the Code whether Xyloma can be retained as the two genera were subsequently lectotypified with different species, but we choose to do so as Xyloma has historically been a widely used name. The alternative would be to include all the species treated here under the later synonym Cryptomyces Grev. (1825), which is unattractive as that genus was originally established for a single, morphologically and ecologically atypical species that is now assigned to Xyloma, and the genus was subsequently used for fungi with diverse phylogenetic affinities.
The species of the Salix clade are restricted to Salix spp. as host plants. The clade is strongly supported in the phylogenetic trees (Fig. 1; Wang QT et al. 2023, Supplementary Figs. 1-3). Although shapes of stromata, ascomata and ascospores are diverse, this clade is treated as a separate genus based on host relationships and phylogenetic analyses.
Type species: Xyloma salicinum Pers. 1794 (lectotype chosen by Höhnel (1917a, b).).
Other accepted species: Species Fungorum – search Xyloma.
References
Fries EM. 1819 – Uppställning af de i Sverige funne Vårtsvampar (Scleromyci). Kungl. Svenska vetenskapsakademiens handlingar. ser. 3, 40: 87–112.
Höhnel F. von. 1917a – Mycologische Fragmente [nos 120–190]. Annales Mycologici 15: 293–383.
Höhnel F. von. 1917b – System der Phacidiales. Berichte der Deutschen Botanischen Gesellschaft 35: 416–422.
Persoon CH. 1794 – Dispositio Methodica Fungorum. Neues Magazin für die Botanik 1: 81–155.
Entry by
Qiu-Tong Wang and Mei-Jun Guo, College of Life Science, Capital Normal University, Xisanhuanbeilu 105, Haidian, Beijing 100048, China.
Published online 27 August 2026