Abstract A new assassin bug species in the genus Rasahus Amyot & Serville, 1843, R. ellipticus sp. nov. , is described based on specimens from Mexico and Argentina. Morphological comparations between the new species and its related species, R. biguttatus (Say, 1832) and R. hamatus (Fabricius, 1781) are provided together with illustrations of habitus and male genitalia of all three species. Rasahus bifurcatus Champion, 1899 was described initially based on submacropterous specimens, and the macropterous male of this species is reported for the first time in the present study. Rasahus sipolisii Fallou, 1887 reinst. stat. , which was synonymized with R. hamatus by Bergroth in 1892, is confirmed to be a valid species, and R. angulatus Coscarón, 1986 syn. nov. should be treated as its junior synonym. Lectotypes of Lestomerus varipes Fallou, 1891, Pirates concisus Walker, 1873, R. bifurcatus Champion, 1899 and R. sipolisii Fallou, 1887 are designated.
Liu et al. (Tue,) studied this question.