Mycetophagus is a genus of hairy fungus beetles in the family Mycetophagidae. There are at least 20 described species in Mycetophagus.

ITIS Taxonomic notes:

• The name Mycetophagus appeared in two or three separate works in 1792, one by Hellwig (in Schneider Neuest Mag. Ent., 1:394), and two by Fabricius (Entomologiae Systematicae, Emendatae et Auctae, Tom. I, Pars II:497; and Determinatio generis Ips affiniumque, Actes de la Société d'Histoire Naturelle de Paris 1:30). Hellwig appears to be the most frequently cited author, so for the moment ITIS will cite Hellwig. Further work would be required to determine earliest available authorship for the genus.
• There is apparently some confusion about subgenera in Mycetophagus. Parsons (1975:94) notes that "Casey's subgenera are not entirely natural and are used here chiefly for convenience in keying to species." Until further research clarifies this issue, ITIS has opted to omit subgenera in this genus.

As discussed by Löbl and Smetana (2011 p21), Hellwig (1792 p408) cited the correct page and number for the genus Lyctus in the second part of Fabricius’ book, demonstrating that he had Fabricius’ book in front of him. As such, Fabricius 1792 clearly has priority over Hellwig 1792 and should be cited as the author of this genus.

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