A world-wide Upper Famennian Trifidorostellum Zone is proposed. It is based on species of the genus found in Canada (Alberta), China (Hunan), USA (Idaho, Montana, New Mexico), USSR (Mugodjary Mountains and North-East). Recall that the following species and subspecies are rejected from the genus: Liorhynchus depressus RZHONSNITSKAYA, 1953, Pseudoleiorhynchus (Pugnax?) plana (= nomen nudum). Liorhynchus plano-ovalis NALIVKIN, 1937, and Trifidorostellum posturalicum pennatum MARTYNOVA, 1970
