ungalpedia – Note 1047, Microcallis
Microcallis Syd.
Citation when using this data: Tian Q et al. 2021 (in prep.) – Fungalpedia, Ascomycota.
Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig 1
Classification: Micropeltidaceae, Microthyriales, Incertae sedis, Dothideomycetes, Pezizomycotina, Ascomycota, Fungi
Epiphytic on the lower surface of leaves, appearing as black dots scattered, hypophyllous. Mycelium composed of branched-reticulate, septate, olivaceous to blackish-brown hyphae. Sexual morph: Ascomata scattered, developing beneath the mycelial pellicle, globose-depressed, attaching it to the leaf surface, olivaceous-brown, membranous, pseudo-ostiolate. Setae scattered, dark brown to black, erect, obtuse. Wall of ascoma pseudoparenchymatous, composed of textura angularis outside, becoming light brown and flattened in the inner region. Asci 8-spored, bitunicate, clavate to ellipsoid, subsessile or sessile. Ascospores overlapping bi-seriate or multi-seriate, oblong-clavate, hyaline, 1- septate, constricted at the septum, thick-walled, smooth-walled, without a mucilaginous sheath. Asexual morph: Undetermined.
Notes: Microcallis Syd. is characterized by globose-depressed ascomata with dark brown to black setae, developing beneath a mycelial pellicle, bitunicate asci, and oblong-clavate, 1-septate ascospores (Sydow 1926, Batista & Ciferri 1962). It was initially placed in Chaetothyriaceae (Sydow 1926, Hansford 1946). Hansford (1946) proposed that the ascomata are too flat, which may be an inaccurate description initially, but he confirmed the position of Microcallis in Chaetothyriaceae, rather than Micropeltidaceae Clem. & Shear. Petrak & Sydow (1934) transferred four species, including the type species M. phoebes Syd., M. amadelpha Syd., M. consociata Syd., and M. megalospora Petrak & Cif. to Chaetothyrina Theiss. (Micropeltidaceae, Microthyriales, Dothideomycetes). Microcallis phoebes shares similar characters with species in Chaetothyrina, hence, we excluded Microcallis from Chaetothyriaceae and assign this genus to Micropeltidaceae.
Type species: Microcallis phoebes Syd., Annls mycol. 24(5/6): 338 (1926).
Other accepted species: Species Fungorum – search Microcallis.
Figure 1 – Microcallis phoebes (E00429570, syntype). a Envelop and collection information of Microcallis phoebes. b Herbarium material. c–e Ascomata on the host surface. f–h Squash mount of ascoma. Note upper wall of radiating cells at the margin. i–k Vertical section of ascoma. l–r Asci. s–u Ascospores. Scale bars: c = 1000 μm, d = 200 μm, e = 100 μm, f, g, i = 50 μm, h, j = 20 μm, k–r = 10 μm, s–u = 5 μm
References
Batista AC, Ciferri R. 1962 – The Chaetothyriales. Sydowia 3, 1–129.
Hansford CG. 1946 – The foliicolous ascomycetes, their parasites and associated fungi. Mycological Papers 15, 1–240.
Petrak F, Sydow H. 1934 – Kritisch–systematisch Originaluntersuchungen über Pyrenomyzeten, Sphaeropsideen und Melanconieen. V. Annales Mycologici 32 (1–2), 1–35.
Sydow H. 1926 – Fungi in intinere costaricensi collecti, pars secunda. Annales Mycologici 24(5–6), 283–426.
Entry by
Qing Tian, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand, School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
Published online 16 December 2021