CHARACTERISTICS OF NEMANIA

Taxa of Nemania have all or most of the following features, some of which are discussed in detail elsewhere herein. Stromata are dark- or dull-colored; are carbonaceous or at least brittle; do not release a colored pigment in 10 % potassium hydroxide (see Ju & Rogers 1996); and usually are more or less pulvinate, attached to the substrate along the entire area of the base. Stromata bear multiple perithecia and these are not easily separable, i.e., perithecia cannot be lifted intact from the stroma with a needle. The stromatal interior of most taxa surrounding the perithecia is initially soft and whitish, persisting into maturity in some taxa, but crushed or lysed in others. Asci are cylindrical, usually long-stipitate, and bear apical rings that have a height/breadth ratio greater than 1/2. Rings of some species are amyloid, bluing in Melzer's iodine reagent without pretreatment (see Nannfeldt 1976); others do not blue in iodine and rather become yellowish or reddish, i.e., they are dextrinoid. Ascospores are yellowish to dark brown, bearing an inconspicuous to conspicuous germ slit on the ventral (more flattened) side or, less commonly, on the dorsal (more convex) side. Those of some species have abruptly narrowed ends which are described in the key and descriptions as "pinched." Ascospores lack a hyaline perispore, at least a conspicuous one that is removed in 10% potassium hydroxide (see Ju & Rogers 1996). The taxa that we currently accept in Nemania lack a gelatinous sheath enclosing the ascospore. Immature ascospores usually bear a cellular appendage that disintegrates as spores attain their mature color. Anamorphs, where known, are of the hyphomycete genus Geniculosporium Chesters & Greenh. or at least are Geniculosporium-like. Colonies usually grow rapidly on scratch malt extract medium (SME, Kenerley & Rogers 1976), producing abundant conidia and, in a few cases, perithecial stromata (see later). Colors of cultures are described according to Rayner (1970).

Recent molecular studies utilizing ITS sequencing (including the 5.8S rRNA gene) (Sánchez-Ballesteros et al. 2000; Granmo et al. 1999) support generic concepts in the Xylariaceae developed on morphological, cultural, and anamorphic criteria (Ju & Rogers 1996 and refs. therein). Nemania is a genus distinct from Hypoxylon, Kretzschmaria, and Entoleuca (Granmo et al. 1999, Sánchez-Ballesteros et al. 2000).  A molecular study including six taxa of Nemania did not strongly support the current species concept (Sánchez-Ballesteros et al. 2000), whereas the species concept of Granmo et al. (1999) was rather strongly supported by molecular data. Sánchez-Ballesteros et al. (2000) speculated that taxa of Nemania could represent a genetic species complex with a range of phenotypic variants that would be indistinguishable by molecular means. This seems unlikely to us based upon our morphological species concept in this genus, but this kind of study should be expanded to include far more species and more isolates of individual taxa.

Many Xylaria species are probably closely related to extant, undiscovered, or extinct Nemania species. The soft white stromatal interiors and the Geniculosporium-like anamorphs are reminiscent of Nemania.  Many Xylaria species have immature ascospores with an evanescent cellular appendage, likewise resembling Nemania species (see later herein and Rogers 1979). Moreover, the propensity of Nemania species to be endophytic is likewise widely seen among Xylaria taxa (see later).