A REDESCRIPTION OF THE MYRMECOPHILOUS GENUS TETRADONIA AND A DESCRIPTION OF A NEW, CLOSELY-RELATED, FREE-LIVING GENUS TETRADONELLA (COLEOPTERA, STAPHYLINIDAE)

Tetradoniais redescribed and a new, closely related genus Tetradonella is described. Questions about their assignment to either the Lomechus ini or Athetini are discussed and a broad range of both pleisiomorphic and apomorphic characters are examined. Taxonomically they show an af finity with both the Athetini and Lomechusini, and are probably rooted close to the point where the two tribes diverge. Further work is nece ssary to determine the tribe to which they belong or whether they shou ld be placed in a new tribe, until then they remain in Lomechusini. In Tetradonia 17 species are redescribed and 18 new species are describe d: Mexico, T. newtoni T. palenquensis; Guatemala, T. minuta T. tikalen sis; Costa Pica, T. ashei T. hansoni T. hirsuta, T. lescheni; Panama, T. akrei; Panama and Costa Plea, T. brooksi, T. laticeps; Panama, Cost a Plea, and Guatemala, T. pusilla; Ecuador, T. pumilia; Brazil, T. alz adae, T. borgmeieri, T. brunneiceps, T. minor, T. planelyra. Tetradone lla has 7 new species: Peru and Costa Pica, T. latiarea (generitype); Peru, T. amazoniensis, T. breviapex, T. peruensis; Costa Pica, T. bell i T. bicolor, T. latipex. Keys to all the species are included. The re lationship between Acanthodonia and Tetradonia is reviewed and Acantho donia is retained as a synonym of Tetradonia. Tetradonia reichensperge ri is synonymized with T. spinipennis, and T. amapaensis with T. alvar engai. Observations in the field and lab show that Tetradonia are able to follow ant trails with a high degree of host specificity although they are not integrated in the colony, and it is suggested that trail following and integration evolved independently instead of representin g different points on a continuum leading to complete integration.