The biology and morphology of the family Trigonalyidae [Trigonalidae] are briefly outlined. The species for which the biology is known are hyperparasitoids. The only European species of this family, Pseudogonalos hahnii [Trigonalis hahniz], is again reported from Italy (from Piedmont) and redescribed. Notes are given on the systematics, distribution and biology of the insect, the hosts of which include the ichnemnonid Ophion luteus parasitzing the noctuid Agrotis latens [Rhyacia latens] and the ichneumonid Enicospilus merdarius parasitizing the noctuid Panolis flammea. none