Within the paleotropical tree genusMacaranga(Thouars 1806) (Euphorbiaceae), the majority of ant-plant species are associated with specializedCrematogaster(Lund 1831) partner ants from the subgenusDecacrema(Myrmicinae). We have now discovered a completely different myrmecophytic system in which an ant species of the Formicinae lives in symbiosis with the peat swamp forest treeMacaranga puncticulata(Gage 1922).M. puncticulatatwigs develop spacious cavities (domatia). An undescribedCamponotus (Colobopsis)(Mayr 1861) species of the C.saundersi-group was the dominant ant inhabitant (65% of the investigated plants) at forest sites, but this species, provisionally named C.(Colobopsis)sp. 1, was only rarely found at open stands. Another 29 opportunistic stem-nesting ant species were collected less frequently. None of them wereCrematogaster (Decacrema)ants.C. (Colobopsis)sp. 1 has never been found to nest away fromM. puncticulata. The mated queens are capable of locating youngM. puncticulataplants and of chewing entrance holes into the domatia. In contrast to all the other obligate plant-ants associated withMacaranga, C.(Colobopsis)sp. 1 never cultivates any trophobionts, neither inside nor outside the domatia. Instead of taking up honey dew from coccids, the ants obtain carbohydrates from extrafloral nectaries along the leaf margins ofM. puncticulata.This food source is an uncommon trait withinMacarangamyrmecophytes. The association of C.(Colobopsis)sp. 1 withM. puncticulatais therefore the first record of a two-partner ant-plant system without endophytic coccids in the genusMacaranga.