Chaetothyriomyces brasiliensis Pereira-Carv., Inácio & Dianese, Mycotaxon 107: 484 (2009)
Index Fungorum number: IF512643; MycoBank number: MB 512643
Colonies effuse, epiphyllous, superficial. Mycelium superficial, brown to dark brown, septate, forming a net-like pellicle. Hyphae 7–19 (10) × 2–4 (3) μm, septate, branched, monilioid, brown. Ascomata 76–130 × 51–74 μm, superficial, located under a mycelial pellicle, brown, dark brown, subglobose or globose, unilocular, smooth; wall with textura ranging from globose to angular. Asci 18–42 (31) × 16–34 (18) μm, broadly clavate, bitunicate, 16-spored. Ascospores 8–15 (12) × 3–5 (4) μm, hyaline, 2-celled, elliptical, non-symmetrical.
Type: Brazil, Mato Grosso do Sul, Campo Grande, Reserva Ecológica da Embrapa at Depate Empaer, on living leaves of Qualea grandiflora Mart. (Vochysiaceae), 16 April 1996, M. Sanchez 1892 (UB Col. Micol. 12116, holotype).
Note: The specimen studied is characteristically a member of the Chaetothyriaceae / Chaetothyriales M.E. Barr (Barr 1979, 1987; Kirk et al. 2001) with dark superficial mycelium typically containing septate monilioid hyphae, and forming a layer on top of globose sometimes setose perithecial ascomata depressed when dried with a pseudoparenchymatous thin-wall; clavate bitunicate asci with transversally septate or muriform hyaline to pale gray ascospores (Kirk et al. 2001). According to Kirk et al. (2001), Chaetothyriaceae includes the genera: Actinocymbe, Biciliopsis Diederich, Ceramothyrium, Chaetothyrium, Euceramia, Microcallis, Phaeosaccardinula, Treubiomyces and Yatesula. Recently, Lumbsch & Huhndorf (2007) considering also the available molecular data accepted the same generic composition for the family, except for Biciliopsis that was properly fitted in Dothideomycetidae incertae sedis. Among this set of genera in the family Chaetothyriaceae, only Euceramia can be contested because of its described unitunicate asci (Batista & Ciferri 1962) and will not be considered here pending epitypification or neotypification. Thus, comparing the specimen with the remaining members of the Chaetothyriaceae, its species is segregated from all genera based on an outstanding character, namely the presence of sixteen ascospores in each and every ascus.
Figure 1. Chaetothyriomyces brasiliensis on a leaf of Qualea grandiflora (Vochysiaceae). 1. A dark ascoma seen under a stereomicroscope (bar = 100 μm). 2–3. Sections through an ascoma showing the disposition of the asci (bars = 20 μm ). 4. An ascoma associated with a wef of superficial mycelium (bar = 50 μm). 5. Bitunicate asci with slightly asymmetrical ascospores.