Fungalpedia – Note 3037, Johnstoniella
Johnstoniella C.L. Hou & P.F. Cannon.
Citation when using this data: Wang QT et al. 2023 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1, 2.
Classification: Rhytismataceae, Rhytismatales, Leotiomycetidae, Leotiomycetes, Pezizomycotina, Ascomycota, Fungi.
Etymology. The name honours Peter Johnston (Landcare Research, New Zealand), who has made many important contributions to the systematics and phylogeny of Rhytismataceae, and to Leotiomycetes in general.
Parasitic on species of Lonicera L. Stromata developing on living leaves, slightly raising above the surface of the leaf, sparse, irregular in shape, up to 6 mm diam. Ascomata mature on dead leaves at the end of spring/beginning of summer of the next year, opening by one, more or less longitudinal split. Sometimes with lip cells. Paraphyses filiform, usually covered by thin gelatinous sheaths. Ascospores filiform, with inconspicuous gelatinous sheaths.
Notes: Based on the LSU-mtSSU phylogenetic tree, the Lonicera clade has high support values (Wang QT et al. 2023), and all species with available sequences to date are restricted to that host genus. They have asci with rostrate apices and filiform ascospores that are significantly shorter than the asci.
Phaeorhytisma Henn. (in Warburg 1899), based on material on Lonicera sp. from Java, was investigated as a possible earlier name for the Lonicera clade. However, the type species has ascomata produced in gall-like structures on living leaves surrounded by crystalline deposits, asci that are not rostrate, and ellipsoidal to fusiform, slightly curved ascospores that may become brown when old (the last feature not observed in the isotype at K(M)). It could well belong to the Rhytismataceae, but no sequences are available (indeed, it appears not to have been seen since the original type collection), and it probably does not belong to Rhytisma s.l.
Phaeorhytisma was treated as a synonym of Criella (Sacc.) Henn. later that year in the same publication (Warburg 1899; it was issued in parts), but remains available for use as it was accepted in its original publication. Criella was based on Rhytisma sect. Criella (Saccardo 1889) with the type Rh. austrocaledonicum Crié described from various species of Symplocos Jacq. (Symplocaceae, Ericales) from New Caledonia. It could represent a further clade within Rhytisma s.l. but again no sequences are available and morphological features need re-examination.
Type species: Johnstoniella yunnanensis C.L. Hou, Q.T. Wang & P.F. Cannon.
Other accepted species: Species Fungorum – search Johnstoniella.
Figure 1 – Johnstoniella yunnanensis on Lonicera sp. (HOU 943/BJTC 201947, holotype). a–b Large stromata with ascomata. c Dry ascomata. d Wet ascomata. Scale bars a–b = 2 mm, c–d = 1 mm.
Figure 2 – Johnstoniella yunnanensis (HOU 943/BJTC 201947, holotype). a Stroma in vertical section. b Detail of a mature ascoma in vertical section. c Paraphyses, a young ascus, an ascus after the liberation of the ascospores, two mature asci with ascospores and discharged liberated ascospores. Scale bars a = 200 μm, b = 100 μm, c = 20 μm.
References
Saccardo PA. 1889 – Sylloge Discomycetum et Phymatosphaeriacearum. Sylloge Fungorum 8: 1–1143.
Warburg O. 1899 – Monsunia. Beiträge zur Kenntniss der Vegetation Süd- und Ostasiatischen Monsungebietes. Vol. 1: 207 pp. Leipzig: Engelmann.
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