Fungalpedia – Note 2631, Stromatopogon
Stromatopogon Zahlbr.
Citation when using this data: Meng QF et al. – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Dothideomycetes genera incertae sedis, Pezizomycotina, Ascomycota, Fungi, Fungi.
The lichenicolous genus Stromatopogon was established by Zahlbruckner (1897) to accommodate the type species Stromatopogon baldwinii Zahlbr. According to the original description, the genus is characterized by its lichenicolous lifestyle on Usena, parasitic ascomata, and pycnoconidia mixed within stromata. The distinction between lichen and the lichenicolous fungus was not well-defined. The ascomata was considered a different fructification from Usnea, leading to the proposal of the new name ‘Stromatopogon’. Diederich (1992a) re-studied the type species S. baldwinii and discovered that it is an Usnea thallus attacked by parasitic fungi. Due to the poor condition of the type specimen, with almost all examined fructifications empty, one conidioma contained microconidia but no spores. Consequently, the type species S. baldwinii was lectotypified based on the macroconidial element. However, it remains uncertain whether the perithecia described in the original reference represent the sexual morph of the same fungus. Diederich (1992a) also studied new samples of S. baldwinii from Tasmania and found that this species produces two completely different kinds of conidia within the same conidioma.
The type species, Stromatopogon baldwinii, is characterized by pycnidial conidiomata, which are immersed in the thick galls of the host, dark brown to black and subspherical. The conidiomata irregularly open from the upper part of the wall by breaking and becoming cupulate. The inner layer of the dark brown wall, formed by pale brown cells, produces two kinds of conidia from separate regions within the same conidioma. The macroconidial morph often predominates but is sometimes absent in young conidiomata. The macroconidia holoblastic, arising singly, often filling the conidiomatal cavity, composed of 2-7 cells, spherical, ellipsoid or obpyriform, rounded at the apex and base, hyaline, thick-walled, and smooth. The conidiophores of microconidia arise from cells identical to the conidiogenous cells of macroconidia, simple or branched, often septate, and hyaline. The microconidia are subcylindrical, with a rounded apex and distinctly truncate base, simple, hyaline, and smooth (Diederich 1992a).
There are three species in Stromatopogon. Besides the type species S. baldwinii which grows on Usena, Diederich et al. (2003) introduced the second species, S. cladoniae Diederich & Sérus., which grows on Cladonia polydactyla. Etayo et al. (2004a) introduced the third species, S. geminatum, which also grows on Usena. Due to the lack of molecular data, the systematic position of this genus remains unclear and it is currently placed within Ascomycota genera incertae sedis by Hyde et al. (2024).
Type species: Stromatopogon baldwinii Zahlbr.
Other accepted species: Species Fungorum – search Stromatopogon
Figure 1 – Stromatopogon Baldwini, a–g redrawn from Zahlbruckner (1897), h–j from Diederich (1992a). a–c Stromata on the Usnea sp. d Cross-section through a stroma. e Stylospores. f Asci. g Pycnoconidia. h Conidiomatal wall, conidiogenous cells, conidiophores, microconidia and macroconidia. i Microconidia. j Macroconidia. Scale bars: h, j = 10 μm.
References
Etayo J, Breuss O. 2004a – Stromatopogon geminatum spec, nova, a further lichenicolous fungus growing on Usnea. Österr. Z. Pilzk. 13, 277–279.
Entry by
Meng QF, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand and School of Public Health, Zunyi Medical University, Guizhou 563000, China.
Published online 23 June 2026