Recent publications have argued that there are potentially serious consequences for researchers in recognising distinct genera in the terminal fusarioid clade of the family
Nectriaceae
. Thus, an alternate hypothesis, namely a very broad concept of the genus
Fusarium
was proposed. In doing so, however, a significant body of data that supports distinct genera in
Nectriaceae
based on morphology, biology, and phylogeny is disregarded. A DNA phylogeny based on 19 orthologous protein-coding genes was presented to support a very broad concept of
Fusarium
at the F1 node in
Nectriaceae
. Here, we demonstrate that re-analyses of this dataset show that all 19 genes support the F3 node that represents
Fusarium sensu stricto
as defined by
F. sambucinum
(sexual morph synonym
Gibberella pulicaris
). The backbone of the phylogeny is resolved by the concatenated alignment, but only six of the 19 genes fully support the F1 node, representing the broad circumscription of
Fusarium.
Furthermore, a re-analysis of the concatenated dataset revealed alternate topologies in different phylogenetic algorithms, highlighting the deep divergence and unresolved placement of various
Nectriaceae
lineages proposed as members of
Fusarium
. Species of
Fusarium s. str.
are characterised by
Gibberella
sexual morphs, asexual morphs with thin- or thick-walled macroconidia that have variously shaped apical and basal cells, and trichothecene mycotoxin production, which separates them from other fusarioid genera. Here we show that the Wollenweber concept of
Fusarium
presently accounts for 20 segregate genera with clear-cut synapomorphic traits, and that fusarioid macroconidia represent a character that has been gained or lost multiple times throughout
Nectriaceae
. Thus, the very broad circumscription of
Fusarium
is blurry and without apparent synapomorphies, and does not include all genera with fusarium-like macroconidia, which are spread throughout
Nectriaceae
(
e.g.
,
Cosmosporella
,
Macroconia
,
Microcera
). In this study four new genera are introduced, along with 18 new species and 16 new combinations. These names convey information about relationships, morphology, and ecological preference that would otherwise be lost in a broader definition of
Fusarium
. To assist users to correctly identify fusarioid genera and species, we introduce a new online identification database, Fusarioid-ID, accessible at
www.fusarium.org
. The database comprises partial sequences from multiple genes commonly used to identify fusarioid taxa (
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