Primary type information: Type-material: lectotype worker (by designation of Heterick, 2006: 101). Type-locality: lectotype Singapore (A.R. Wallace). Type-depository: OXUM. Type-specimen: lectotype CASENT0008625. Secondary type information: Paratype-material: 3 paralectotype workers. Paratype-locality: same as for lectotype. Paratype-depository: OXUM. Type notes: Syntypes of both Monomorium vastator and Monomorium fragilis bear the same label, “House ants Singapore, very destructive”. Both probably had their origin in a single series, one part of which (Monomorium vastator) went direct to Smith, the other (Monomorium fragilis) which came to him later, via the W.W. Saunders collection.