Introduction to Nemania



The old generic name Nemania S. F. Gray was resurrected by Pouzar (1985 a, 1985 b) in order to accommodate a group of species related to Hypoxylon serpens ( Pers.: Fr.) J. Kickx fil. that were previously classified by Miller (1961) in Hypoxylon Bull. section Papillata subsection Primo-cinerea. This generic concept was later accepted by other authors, for the cultural data presented by Petrini and Rogers (1986) and the narrower delimitation of Hypoxylon proposed by Ju and Rogers (1996) led to the necessity to segregate this group from Hypoxylon.

Nemania is distinguished from Hypoxylon on the basis of the following characters, developed by Granmo et al. (1999), Laessøe et al. (2000) and Ju and Rogers, (2002): in Nemania, stromata are dark brown to black, one-layered, more or less carbonaceous and usually have, at least at first stages of their development, a whitish soft tissue between and/or beneath the perithecia; they lack coloured granules and do not yield pigments in 10% KOH. Ostioles are typically papillate. Asci are provided with an apical apparatus usually higher than broad or at least cuboid. Ascospores are frequently pale brown, mostly with an inconspicuous germ slit which is located on the less convex side, and lack a perispore dehiscing in 10% KOH. Immature ascospores often bear a fugacious and inconspicuous cellular appendage. Anamorphs are referable to Geniculosporium Chesters and Greenhalg. In addition, young stromata growing under the anamorph usually keep a loose hyphal cottony coating which is coloured in shades of white, brown, ochreous grey, grey or greenish yellow and vanishes at maturity. Most of these features show that affinities of Nemania rather lie with effused forms of the heterogenous genus Xylaria than with Hypoxylon. Moreover, D. N. A. sequencing of various xylariaceous taxa carried out by Granmo et al. (1999) supports the segregation of Nemania as a distint clade.

For synonymy of taxa treated further, the reader is referred to the above authors (Granmo et al., 1999; Ju and Rogers, 2002).

A thorough and systematic examination of all Nemania specimens collected during this study showed that the stromatal morphology does not allow a reliable distinction between most of European Nemania taxa, for intraspecific variations often have a broader range than interspecific differences. Nemania serpens represents about 90% of the collected specimens in our area, and its stromatal variations make its field identification nearly impossible, but fortunetaly it is readily recognized microscopically owing to the dextrinoid reaction of the ascal apical apparatus. In our experience, N. diffusa, N. aenea var. aureolutea, N. chestersii, N. confluens and N. serpens var. colliculosa are not uncommon, while other taxa occur occasionally to very rarely.

In this study we present five unnamed species which more or less deviate from the known Nemania species. All of them might represent new taxa, but they are represented by too scanty material. Additional records are expected in future, so that they can be cultured and compared to known taxa.

Nemania species are mostly found growing on decorticated rotten wood of Angiosperms. Nemania diffusa and N. aenea var. aureolutea are distinctive in growing likewise on bark, and interestingly N. confluens and N. serpens were once recorded on wood of Abies alba. As many other xylariceous fungi, Nemania species have been isolated as endophytes (L. Petrini and O. Petrini, 1985; Ju and Rogers, 2002), but unlike in other genera, none of them is apparently host-specific.