Sentence:  The <WSD>yuanyang</WSD> are the male and female repectively of Anas galericulata, commonly called by Europeans "Mandarin duck." These beautiful water-fowl manifest when mated a singular degree of attachment for each other, and they have hence been elevated into the emblems of connubial affection and fidelity. 
Meaning of the word marked with <WSD> tags:  (China) A pair of mandarin ducks, one male and one female, as a symbol of faithful union.