The ghost fungus Omphalotus nidiformis (Berk.), new to Indonesia, poisoned foragers

Most Indonesian wild mushrooms remain unexplored, including genus Omphalotus. Omphalotus nidiformis (Omphalataceae), which is primarily distributed in arid parts of Australia and is globally known as a poisonous mushroom. No prior report exists on this species' occurrence in Indonesia. In November 2021, Indonesian foragers consumed the pleurotoid mushroom, which was misidentified as Pleurotus, and were poisoned at Mount Tangkuban Perahu, West Java. This study aimed to ensure the taxonomical position of the poisonous macrofungus and record the poisoning event to increase public awareness in Indonesia. Fresh basidiomata materials were assessed for morphological and molecular information. The specimen's morphology was described based on its macroscopic and microscopic characteristics. The molecular and phylogenetic approach used internal transcribed spacer (ITS) 4/5 sequence data. Combined morphological and molecular analyses confirmed the taxonomical position of our specimen as O. nidiformis (Berk.). Morphology illustrations and the phylogenetic tree of O. nidiformis are provided. This is the first report on O. nidiformis distribution in Indonesia, and this study contributed to Indonesia's macrofungi diversity data. Schima wallichii was confirmed as a host for O. nidiformis. Additionally, the poisoned foragers had symptoms of nausea and vomiting, as well as weakness, perspiration, and trembling. Our report indicated the urgent need for mycological dissemination to the public in Indonesia regarding O. nidiformis identification.