Abstract
Species of Leptographium are characterized by mononematous or synnematous conidiophores and are commonly associated with different arthropods. Some of them also produce a sexual state characterised by globose ascomata with elongated necks. Compared to investigations on coniferous trees, the occurrence of Leptographium species on hardwood trees has been poorly studied in Europe. During a survey of ophiostomatoid fungi on various hardwood tree species in Norway and Poland, three unusual species, which fit in the broader morphological description of Leptographium spp., were found in association with Trypodendron domesticum, Trypodendron signatum and Dryocoetes alni, and from wounds on a variety of hardwoods. Phylogenetic analyses of sequence data for six different loci (ITS1–5.8 S–ITS2, ITS2-LSU, ACT, β-tubulin, CAL, and TEF-1α) showed that these Leptographium species are phylogenetically closely related to the species of the Grosmannia olivacea complex. The first species forms a well-supported lineage that includes Ophiostoma brevicolle, while the two other new taxa resided in a separate lineage; possibly affiliated with Grosmannia francke-grosmanniae. All the new species produce perithecia with necks terminating in ostiolar hyphae and orange-section shaped ascospores with cucullate, gelatinous sheaths. These species also produce dark olivaceous mononematous asexual states in culture. In addition, two of the newly described species have a second type of conidiophore with a short and non-pigmented stipe. The new Leptographium species can be easily distinguished from each other by their appearance and growth in culture. Based on novel morphological characters and distinct DNA sequences, these fungi were recognised as new taxa for which the names Leptographium tardum sp. nov., Leptographium vulnerum sp. nov., and Leptographium flavum sp. nov. are provided.
Highlights
Species of Leptographium Lagerb. and Melin (Lagerberg et al 1927) are commonly associated with bark beetles and weevils (Jacobs and Wingfield 2001)
G. francke-grosmanniae has affiliation to L. vulnerum and L. flavum based on analysis of the internal transcribed spacer (ITS) and ß-tubulin sequences
The sexual states of these three new species were highly similar to those from species that comprise the G. olivacea complex
Summary
Species of Leptographium Lagerb. and Melin (Lagerberg et al 1927) are commonly associated with bark beetles and weevils (Jacobs and Wingfield 2001). Some important tree diseases are known, e.g. Leptographium wageneri complex species that is responsible for black stain root disease (BSRD) on conifers in western North America (Goheen and Cobb 1978). In contrast to the conifers, occurrence of Leptographium spp. on hardwood trees has been relatively poorly investigated in Europe. Leptographium species have previously been isolated from the roots of various hardwood trees in the southeastern United States (Jacobs et al 2006), and from beetles infesting hardwoods in China (Paciura et al 2010). Was for a long time the only Leptographium/Grosmannia species reported from hardwoods (Davidson 1971; Jacobs and Wingfield 2001). Our recent research (Jankowiak et al 2017) expanded the knowledge of hardwood-infecting Leptographium spp. in Europe by describing two new species of Leptographium that were assigned to the Antonie van Leeuwenhoek (2018) 111:2323–2347 newly defined Grosmannia grandifoliae species complex
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
