Taxonomic position of Gremmeniella abietina and related species: a reappraisal

Abstract

A comparative study of isolates and their corresponding herbarium specimens of Gremmeniella spp. from pine, spruce, and balsam fir, of Ascocalyx laricina from larch, and of Ascocalyx abietis from balsam fir was conducted using morphological and cultural characteristics as well as electrophoresis tests on 12 and 10 – 15% gradient polyacrylamide gels. In addition, the conidia and the ascospores of the specimens were treated with 4′,6-diamino-2-phenylindole to determine the number of nuclei per cell. Ascocalyx abietis is quite distinct in the morphology of its anamorph and in its cultural characteristics from all other samples studied. The specimens from larch differ from the others by their 2-celled ascospores and their cultural characters. Among specimens from pines and from Picea and Abies, minor morphological and cultural differences were found. The electrophoresis tests confirm the differences observed in the cultural studies. The statistical analysis of the results supports the following classification of the specimens studied: within Gremmeniella abietina, two varieties are recognized, a var. typical, with the known "European" and "North American" races from Pinus and the "Asian" race from Abies sachalinensis, and a new variety, var. balsamea, comprising the isolates from Picea and Abies (Québec). A new combination is proposed in Gremmeniella for Ascocalyx laricina. Ascocalyx abietis is retained as a separate genus.