Notes: Grosmannia was originally erected by Goidànich (1935) to accommodate sexual species of Ceratostomella with leptographium-like asexual morphs (Davidson 1942). The genus was later treated as synonym of both Ophiostoma (Siemaszko 1939) and Ceratocystis (Bakshi 1951). Zipfel et al. (2006) showed that Ophiostoma and Grosmannia were distinct from each other based on ITS and LSU sequences, and separated the two genera based on these and morphological differences. However, the focus of the Zipfel et al. (2006) study was primarily on sexually reproducing species.
De Beer & Wingfield (2013) included sequence data for many more asexual Leptographium spp. in their study and showed that Leptographium and Grosmannia spp. grouped together, along with other previously unassociated Ophiostoma spp. They applied the older name, Leptographium to this group, rather than Grosmannia, which following the dual nomenclature system (McNeill et al. 2012) had preference because it was considered a sexual genus (De Beer & Wingfield 2013). They referred to the lineage as Leptographium s.l., even though the lineage did not show strong monophyletic support. The type species of Grosmannia (G. penicillata) grouped in a lineage distinct from the type species of Leptographium (L. lundbergii). However, they recommended that novel species grouping in what they referred to as the G. penicillata complex should be treated as Grosmannia species. This was until more robust analyses could confirm whether the G. penicillata complex should be treated as a distinct genus.
Based on the data emerging from the present study, we have reinstated Grosmannia as a genus distinct from Leptographium, for species that produce leptographium-like asexual morphs and have allantoid, hyaline and aseptate ascospores. These species are commonly associated with conifer-infesting bark beetles in the Northern Hemisphere (Jacobs & Wingfield 2001, Linnakoski et al. 2012). Based on our phylogenetic analyses, Grosmannia includes the fungus previously known as G. penicillata s.s. (referred to here as the G. penicillata complex), G. abieticola and L. taigense (Lineage C), and the newly recognised G. grandifoliae complex (Jankowiak et al. 2017).