Byssothecium
Byssothecium Fuckel
Index Fungorum number: IF 714
Saprobic on submerged wood in freshwater or decaying wood in terrestrial habitats Sexual morph: Ascomata gregarious, erumpent to superficial, uniloculate, subglobose, ovoid to obpyriform, black, coriaceous, with a central ostiolate papilla. Peridium composed of brown, rectangle, pseudoparenchymatous cells, somewhat thinner at base. Pseudoparaphyses dense, cellular, hypha-like, hyaline, septate, embedded in a gelatinous matrix, anastomosing between and above the asci. Asci 8-spored, bitunicate, fissitunicate, cylindrical to clavate, pedicellate. Ascospores biseriate at the apex, becoming uniseriate near the base, ellipsoidal to fusiform, straight to slightly curved, hyaline to brown, usually paler at end cells, septate, basically symmetric, smooth to minutely verrucose, thin-walled (Crane et al. 1992; Pem et al. 2019). Asexual morph: chaetophoma-like (Boise 1983) (Descriptions from Dong et al. 2020).
Type species: Byssothecium circinans Fuckel
Notes: Byssothecium is characterized by ellipsoidal to fusiform, hyaline to brown ascospores usually with bipolar paler cells (Crane et al. 1992; Pem et al. 2019). The asexual morph of B. circinans was produced in culture and characterized by minute conidiomata, phialidic conidiogenous cells and hyaline, aseptate conidia, which are similar to Chaetophoma (Boise 1983).
Savoryella E.B.G. Jones & R.A. Eaton shares similar morphological characters with Byssothecium in having cylindrical asci, ellipsoidal, 3-septate ascospores with brown central cells and paler end cells (Jones and Eaton 1969; Dayarathne et al. 2019). The ascomata have a long neck in Savoryella, but it is lacking in Byssothecium. Phylogeny separates them in different classes: Byssothecium in Dothideomycetes (Lumbsch and Lindemuth 2001), and Savoryella in Sordariomycetes (Dayarathne et al. 2019).
One putative strain of Byssothecium circinans (CBS 675.92) clustered in Massarinaceae in Schoch et al. (2009). Zhang et al. 2009b) found that B. circinans clustered basal to Melanommataceae based on combined LSU and SSU dataset, while clustered in Massarinaceae based on RPB2 dataset. Because B. circinans considerably differs from Massarina in morphology, such as black, erumpent ascomata, ellipsoidal to fusiform ascospores with pigmented central cells and hyaline end cells (Crane et al. 1992), and had an unstable relationships in the phylogenetic tree (Zhang et al. 2009b). Byssothecium circinans was not assigned to Melanommataceae and treated as an unresolved species (Zhang et al. 2009b, c). Based on combined LSU, SSU and RPB2 dataset, B. circinans formed a stable clade in Melanommataceae (Zhang et al. 2012; Hyde et al. 2013; Tanaka et al. 2015; Voglmayr and Jaklitsch 2017; Pem et al. 2019). (Notes from Dong et al. 2020).
List of freshwater Byssothecium species (Dong et al. 2020).
Byssothecium circinans Fuckel, Bot. Ztg. 19: 251 (1861)
Synonymy: Hendersonia circinans (Fuckel) Sacc., Syll. fung. (Abellini) 3: 431 (1884)
Heptameria circinans (Fuckel) Cooke, Grevillea 18(no. 86): 30 (1889)
Leptosphaeria circinans (Fuckel) Sacc., Syll. fung. (Abellini) 2: 88 (1883)
Melanomma vindelicorum Rehm, Ber. naturhist. Augsburg 26: 116 (1881)
Passeriniella circinans (Fuckel) Sacc., Syll. fung. (Abellini) 11: 326 (1895)
Trematosphaeria circinans (Fuckel) G. Winter, Rabenh. Krypt.-Fl., Edn 2 (Leipzig) 1.2: 227 (1885)
Trematosphaeria vindelicorum (Rehm) Sacc., Syll. fung. (Abellini) 2: 122 (1883)
Freshwater distribution: Hungary (Révay and Gönczöl 1990; Gönczöl and Révay 1993)
Byssothecium flumineum J.L. Crane, Shearer & Huhndorf, Mycologia 84(2): 236 (1992)
Freshwater distribution: USA (Crane et al. 1992)
Key to freshwater Byssothecium species (Dong et al. 2020).
1. Ascospores 7.3−9.2 µm wide........... B. flumineum
1. Ascospores 10−12 µm wide............. B. circinans
References
Boise J (1983) On Trematosphaeria circinans and reinstatement of the genus Byssothecium. Mycologia 75:666–669
Crane JL, Shearer CA, Huhndorf SM (1992) A new species of Byssothecium (Loculoascomycetes) from wood in fresh water. Mycologia 84:235–240
Dayarathne MC, Maharachchikumbura SSN, Jones EBG, Dong W, Devadatha B, Yang J, Ekanayaka AH, De Silva W, Sarma VV, Al-Sadi AM, Khongphinitbunjong K, Hyde KD, Zhao RL (2019) Phylogenetic revision of Savoryellaceae and evidence for its ranking as a subclass. Front Microbiol 10:840
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Gönczöl J, Révay A (1993) Further studies on fungal colonization of twigs in the Morgó stream, Hungary. Nova Hedwigia 56:531–542
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Jones EBG, Eaton RA (1969) Savoryella lignicola gen. et sp. nov. from water-cooling towers. Trans Brit Mycol Soc 52:161–174
Lumbsch HT, Lindemuth R (2001) Major lineages of Dothideomycetes (Ascomycota) inferred from SSU and LSU rDNA sequences. Mycol Res 105:901–908
Pem D, Jeewon R, Bhat DJ, Doilom M, Boonmee S, Hongsanan S, Promputtha I, Xu JC, Hyde KD (2019b) Mycosphere notes 275–324: a morpho-taxonomic revision and typification of obscure Dothideomycetes genera (incertae sedis). Mycosphere 10:1115–1246
Révay A, Gönczöl J (1990) Longitudinal distribution and colonization patterns of wood-inhabiting fungi in a mountain stream in Hungary. Nova Hedwigia 51:505–520
Schoch CL, Crous PW, Groenewald JZ, Boehm EWA, Burgess TI, de Gruyter J, de Hoog GS, Dixon LJ, Grube M, Gueidan C, Harada Y, Hatakeyama S, Hirayama K, Hosoya T, Huhndorf SM, Hyde KD, Jones EBG, Kohlmeyer J, Kruys A, Li YM, Lucking R, Lumbsch HT, Marvanova L, Mbatchou JS, McVay AH, Miller AN, Mugambi GK, Muggia L, Nelsen MP, Nelson P, Owensby CA, Phillips AJL, Phongpaichit S, Pointing SB, Pujade-Renaud V, Raja HA, Plata ER, Robbertse B, Ruibal C, Sakayaroj J, Sano T, Selbmann L, Shearer CA, Shirouzu T, Slippers B, Suetrong S, Tanaka K, Volkmann-Kohlmeyer B, Wingfield MJ, Wood AR, Woudenberg JHC, Yonezawa H, Zhang Y, Spatafora JW (2009) A class-wide phylogenetic assessment of Dothideomycetes. Stud Mycol 64:1–15
Tanaka K, Hirayama K, Yonezawa H, Sato G, Toriyabe A, Kudo H, Hashimoto A, Matsumura M, Harada Y, Kurihara Y (2015) Revision of the Massarineae (Pleosporales, Dothideomycetes). Stud Mycol 82:75–136
Voglmayr H, Jaklitsch WM (2017) Corynespora, Exosporium and Helminthosporium revisited–new species and generic reclassification. Stud Mycol 87:43–76
Zhang Y, Crous PW, Schoch CL, Hyde KD (2012) Pleosporales. Fungal Divers 53:1–221
Zhang Y, Schoch CL, Fournier J, Crous PW, De Gruyter J, Woudenberg JHC, Hirayama K, Tanaka K, Pointing SB, Spatafora JW, Hyde KD (2009a) Multi-locus phylogeny of Pleosporales: a taxonomic, ecological and evolutionary re-evaluation. Stud Mycol 64:85–102
Zhang Y, Wang HK, Fournier J, Crous PW, Jeewon R, Pointing SB, Hyde KD (2009b) Towards a phylogenetic clarification of Lophiostoma/Massarina and morphologically similar genera in the Pleosporales. Fungal Divers 38:225–251
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