New species of Chrysolina Motschulsky, 1860 (Coleoptera: Chrysomelidae) – the first representative of the subgenus Pleurosticha from Mongolian Altai

New species Chrysolina shapkini sp. n. is described from Western Mongolia (Hovd aimak, 50 km S Mankhan), which proved to be the first representative of the subgenus Pleurosticha Motschulsky, 1860. This subgenus is peculiar to the mountains of South Siberia but has never recorded from the Mongolian Altai earlier. New species can be recognized by such combination of characters as weakly convex elongate-ovate body, flat elytral intervals and aedeagus shape