The study of the male genitália of two from the five known species of the oriental genus Linshcosteus Distant -: L. costalis Ghauri e L. kali Lent & Wygodzinsky -, with emphasis on the comparative aspects of the five structures which have shown more differences. The general aspects of these genitalia follow what the authors had observed in previous works published for the other genera of the tribe Triatomini, subfamily Triatominae. The external morphology, which characterizes the genus, is peculiar, because of the short length of the rostrum which only reaches or approaches the posterior level of the eyes, when observed by profile and rest position, besides not existing a stridulatory prosternal sulcus too.