Taxonomy and phylogeny of the Leptographium olivaceum complex (Ophiostomatales, Ascomycota), including descriptions of six new species from China and Europe

Abstract

TheLeptographium olivaceacomplex encompasses species in the broadly defined genusLeptographium(Ophiostomatales, Ascomycota) that are generally characterized by synnematous conidiophores. Most species of the complex are associates of conifer-infesting bark beetles in Europe and North America. The aims of this study were to reconsider the delineation of known species, and to confirm the identity of several additional isolates resemblingL. olivaceathat have emerged from recent surveys in China, Finland, Poland, Russia, and Spain. Phylogenetic analyses of sequence data for five loci (ACT, TUB, CAL, ITS2-LSU, and TEF-1α) distinguished 14 species within the complex. These included eight known species (L. cucullatum,L. davidsonii,L. erubescens,L. francke-grosmanniae,L. olivaceum,L. olivaceapini,L. sagmatosporum, andL. vescum) and six new species (herein described asL. breviuscapum,L. conplurium,L. pseudoalbum,L. rhizoidum,L. sylvestris, andL. xiningense). New combinations are provided forL. cucullatum,L. davidsonii,L. erubescens,L. olivaceum,L. olivaceapini,L. sagmatosporumandL. vescum. New Typifications: Lectotypes are designated forL. olivaceum,L. erubescensandL. sagmatosporum. Epitypes were designated forL. olivaceapiniandL. sagmatosporum. In addition to phylogenetic separation, the synnematous asexual states and ascomata with almost cylindrical necks and prominent ostiolar hyphae, distinguish theL. olivaceumcomplex from others inLeptographium.