Introduction to Rosellinia

           

Introduction
The temperate species of the genus Rosellinia De Not. (including European species) received a modern monographic treatment by L. E. Petrini (1993), and the present study follows her subgeneric classification in Rosellinia, Corrugata and Calomastia subsections, and her species concepts.

According to the broadly accepted current concept of the genus, Rosellinia is delimited within the Xylariaceae by five main characters: the stromata are uniperitheciate (rosellinioid), superficial, subglobose, associated, at least when immature, with a hyphal mat usually called subiculum, and associated with a Geniculosporium-like anamorph (including Dematophora R. Hartig and Geniculosporium Chesters & Greenhalgh). Until this fundamental work, the genus Rosellinia was at the same time full of irrelevant taxa and known through only a few ones (Dennis, 1978). Her narrower delimitation of Rosellinia led L. E. Petrini (1993) to move taxa excluded from this genus to Amphisphaerella, Anthostomella, Astrocystis , Coniochaeta, Xylaria and other sordariaceous or xylariaceous genera. On the other hand, R. mammaeformis proved to be a complex of related species (Petrini et al., 1989).

Some disagreement over the status of the genus Astrocystis Berk. & Br., which accomodates Rosellinia-like fungi devoid of subiculum but with stromata splitting the host surface or with a carbonaceous extension at the base, associated with Acanthodochium Samuels, Rogers & Nagasawa anamorph, persists between different authors. Astrocystis is recognized by Petrini (1993; 2003) and Lsse & Spooner (1994), but synonymized with Rosellinia by Ju & Rogers (1990; 1995) and San Martin & Rogers (1994).

Relations of Rosellinia species with their hosts range from saprophytism for most of them (Petrini, 1993) to parasitism [root pathogenicity of R. necatrix, R. desmazieresii (Francis, 1985) and probably R. buxi, needle blights of conifers involving R. mycophila (Francis, 1986)]. Rosellinia thelena has been reported as endophyte of conifers, and some other species are likewise suspected of endophytism (Petrini, 1993).

The present study describes and illustrates most of best known European species of Rosellinia, except five species which are very rare or only known from the type collection (i. e., R. etrusca, R. evansii, R. glabra, R. medullaris and R. saccardii) and, curiously, three species known to have an arctic-alpine distribution (i. e., R. abscondita, R. diathrausta and R. nectrioides ) which have not yet been reported from the Pyrnes. Our reports of R. helvetica, R. susimilis and R. thelena var. microspora are likely to be the first from France.