The Pacific Tree-Parasitic Fungus Exhibits Monokaryotic Fruiting, Showing Phenotypes Known from Bracket Fungi and from .

is a wood-destroying parasitic edible mushroom growing on diverse broad-leafed trees in New Zealand and other Pacific areas. Recent molecular systematics of European , a newly delimited Asian phylum and of related species, corroborated the distinction of the chiefly saprobic cultivated edible mushroom from . Here, we show that exhibits a morpho-physiological trait characteristic to its European cousin, i.e., monokaryotic fruiting (basidiome formation without mating). Monokaryotic fruiting structures formed by ICMP 11668-derived monokaryons were categorized into four phenotypes. One of them displays ulcer-like structures previously reported from bracket fungi. Histology of dikaryotic and monokaryotic fruiting structures revealed anatomical commonalities and differences between them, and towards monokaryotic fruiting structures of . Mating experiments with strains representative of each fruiting phenotype identified compatible sibling monokaryons. Given reports on hypothetically monokaryotic basidiome field populations of '', it seems worthwhile to prospectively investigate whether monokaryotic fruiting s.str. occurs in nature. Sampling from such populations including karyotyping, comparative -omics, and competition assays may help to answer this question and provide evidence whether this trait may confer competitive advantages to a species capable of it.