Fetching details from the dictionary...
saucer
person (group, institution, etc.) to take over a position or matter; receptacle (e.g. of funds); receiver
カップを受け皿に載せて出した。
I placed the cup on a saucer and served it.
受け皿がなかったのでカップだけで提供した。
As there was no saucer, I served just the cup.
紅茶の正式な作法ではカップに必ず受け皿を添える。
In the formal etiquette of tea, a saucer must always accompany the cup.