The habitat and the territorial and reproductive behaviours of this recently discovered Bornean euphaeid damselfly are described. It breeds in narrow shady streams in lowland forest in northern Borneo. Territories are defended vigorously against conspecific males. Some fights take the form of head to head contests during which the combatants can fly high into the forest canopy. Males show considerable site tenacity and return day after day to the same small section of stream. Females climb underwater down protruding branches to oviposit into decaying twigs or leaves. Males remain perched above the oviposition site during the early part of the oviposition bout, but increasingly towards the end, return regularly to their preferred territorial perches.