Hydrobasileus brevistylus (Water Prince) ranges in Australia from north Northern Territory, the so-called Top End, around Cape York and down the east coast to north-eastern New South Wales. It is also in Indonesia, Papua New Guinea and the Solomon Islands. The black abdomen with pairs of yellow spots on the dorsal side make it quite distinctive.
It has an irritating habit of continually flying without pause, that I ever noticed. During our Queensland excursion of 2019 we encountered it quite frequently and I managed to capture several in-flight shots, even including a tandem pair from Sippy Downs.