Formica diffidens Walker, 1859: 372 (w.; not q) SRI LANKA. Indomalaya.
Donisthorpe, H. 1932b. On the identity of some ants from Ceylon described by F. Walker. Annals and Magazine of Natural History (10)9:574-576.
Walker, F. 1859. Characters of some apparently undescribed Ceylon insects. [part]. Annals and Magazine of Natural History (3)4:370-376.