Four new species of the fungus gnat genus Tetragoneura Winnertz, 1846 and a key to the six Nearctic species (Diptera, Mycetophilidae).

Four new Nearctic species of the fungus gnat genus Tetragoneura Winnertz, 1846 were discovered in eastern North America. Tetragoneura polyspina Taber is known from Canada and the northern United States, Tetragoneura canada Taber is known only from its boreal namesake country, Tetragoneura dixie Taber is known only from the austral United States, and Tetragoneura caligula Taber is known only from the Great Lakes region of the United States. With the two recently described species Tetragoneura caliga Taber and Tetragoneura lustra Taber, and the designation of Tetragoneura nitida Adams, 1903 as a nomen dubium, a total of six Nearctic species of this genus are currently known.