Antrusa montecristiensis, a new species of Dacnusini from Montecristo island (Italy), is described, illustrated, and compared with allied species. Specific keys of the genus Antrusa for the West Palaearctic region are provided. The preimaginal phases and the venom apparatus of A. curtitempus Fischer, Tormos, Docavo & Pardo, are described, illustrated, and compared with species of allied genera. The larva stages are similar to those of Dacnusa; the immature larvae differ in the number and distribution of the setae of the abdominal and thoracic segments, and the mature larva in the type of the tegumental differentations of the thorax and abdomen as well as in the number and size of the sensilla of the maxillary palpi. The venom apparatus of this species is very similar to that of Antrusa flavicoxa (Thomson), differing from it in length of the reservoir and the number of gland filaments.