We recorded a new species of Cossidae – Acossus terebrus (Denis & Schiffermüller, 1776) – for Mongolia (Tov Aimak). We also report on the most northern habitat of the cossid genus Gobibatyr Yakovlev, 2004 (North-West Mongolia, Bayan-Ulegej Aimak), which shows the permeability of the Mongolian Altai Mountain Range for some elements of the Dzungarian fauna. Additionally, our sampling resulted in adding new localities to the ranges of Catopta perunovi Yakovlev, 2007 and Cecryphallus nubila (Staudinger, 1895) (first discovered in Hovd Aimak).