Xylaria Hill ex Schrank, Baier. Fl. (München) 1: 200 (1789)
Xylariomycetidae, Xylariales, Xylariaceae, Xylaria
Saprobic on deciduous dead wood or endophytes of various plants. Sexual morph: Stromata extremely variable in size and shape, simple to branched from the base, nearly sessile or rising from long rooting stipes, always with flattened to mucronate sterile apices, whitish when immature, gradually turning silvery grey and eventually black, longitudinally lined delimiting narrow strips, perithecial contours most often discreet in well-developed stromata; leathery, black, homogeneous, white to cream, with a slightly darker core, stipes cylindrical to strap-like, longitudinally wrinkled, black, with a hairy-tomentose, extended base. Perithecia subglobose, immersed to slightly exposed. Ostioles if present raised-discoid, grey brown to black, with a low conical papilla at the center. Asci (6–)8-spored, unitunicate, cylindrical, long pedicellate, with tubular, apical ring, bluing in Melzer’s reagent. Paraphyses thin, hypha-like, hyaline, septate. Ascospores overlying uniseriate in the ascus, intermediate brown, most often ellipsoid-inequilateral, with narrow to broadly rounded ends, smooth-walled, with a fugacious cellular appendage, usually vanishing at maturity, containing two large guttules, with a conspicuous straight germ slit, 1/2–4/5 spore-length on the flattened side. A typical ascospores may have severe ends, slightly oblique or sinuous germ slits located next to one end, or on the convex side. Asexual morph: Where known geniculosporium–like, hyaline to light brown, smooth, branched conidiophores bearing hyaline, roughened or smooth, ellipsoidal conidia (adapted from Ju & Rogers 1996; Stadler et al. 2014, Maharachchikumbura et al. 2016).
Type species: Xylaria hypoxylon (L.) Grev., Fl. Edin.: 355 (1824)
Notes: Mostly, species of Xylaria are characterized by large stromata, cylindrical asci with long pedicels, ellipsoidal, dark ascospores in their sexual and geniculosporium-like asexual morph (Ju & Rogers 1996, Stadler et al. 2013). Xylaria is a highly diversified genus, most likely exceeding 500 species (Peršoh et al. 2009). Most Xylaria species are saprobes growing on moist, decaying dicotyledonous wood and less often on monocotyledons, fruits, seeds and fallen leaves. The endophytic species are common in tropical plants. Interestingly, the subgenus Pseudoxylaria is associated with termite nests, mainly macrotermitine termites (Visser et al. 2009, Hsieh et al. 2010). Based on rDNA sequences data, Arthroxylaria and Geniculisynnema were synonymized under Xylaria (Seifert et al. 2002, Okane & Nakagiri 2007, Réblová et al. 2016). The significant variations of the characters of Xylaria species might be the result of many convergent evolution within the genus (Lee et al. 2000).
Species illustrated in this entry:
Xylaria hypoxylon (L.) Grev.
Hsieh HM, Lin CR, Fang MJ, Rogers JD et al. 2010 – Phylogenetic status of Xylaria subgenus Pseudoxylaria among taxa of the subfamily Xylarioideae (Xylariaceae) and phylogeny of the taxa involved in the subfamily. Molecular Phylogenetics and Evolution 54, 957–969
Ju YM, Rogers JD. 1996 – A revision of the genus Hypoxylon. Mycologia Memoir No. 20. APS Press, St. Paul
Lee JS, Ko KS, Jung HS. 2000 – Phylogenetic analysis of Xylaria based on nuclear ribosomal ITS1-5.8S-ITS2 sequences. FEMS Microbiology Letters 187, 89–93
Maharachchikumbura SSN, Hyde KD, Jones EBG, McKenzie EHC et al. 2016 – Families of Sordariomycetes. Fungal Diversity 79, 1–317
Okane I, Nakagiri A. 2007 – Taxonomy of an anamorphic xylariaceous fungus from a termite nest found together with Xylaria angulosa. Mycoscience 48, 240–249
Peršoh D, Melcher M, Graf K, Fournier J et al. 2009 – Molecular and morphological evidence for the delimitation of Xylaria hypoxylon. Mycologia 101, 256–268
Réblová M, Miller AN, Rossman AY, Seifert KA et al. 2016 - Recommendations for competing sexual-asexually typified generic names in Sordariomycetes (except Diaporthales, Hypocreales, and Magnaporthales). IMA fungus 7, 131-153
Seifert KA, Gams W, Louis-Seize GW. 2002 – Arthroxylaria elegans, a new coprophilous anamorphic fungus allied with the Xylariaceae, with notes on the genus Bisporostilbella.
Czech Mycology 53, 297–307
Stadler M, Kuhnert E, Persŏh D, Fournier J. 2013 – The Xylariaceae as model example for a unified nomenclature following the ‘‘One fungus-one name’’ (1F1N) concept. Mycology: An International Journal on Fungal Biology 4, 5–21
Visser AA, Ros VID, de Beer ZW, Debets AJM et al. 2009 – Levels of specificity of Xylaria species associated with fungus-growing termites: a phylogenetic approach. Molecular
Ecology 18, 553–567