During studies of mangrove communities in central Vietnam (Nhatrang Bay, Tre Is and Dam Bay) a heterosexual pair of pontoniine shrimp, Neoanchistus cardiodytes, was found in the mantle cavity of the deeply burrowing bivalve Mactra grandis (Mactridae). This is the fourth record of pontoniine shrimps in symbiosis with burrowing bivalves, the second record of this species as well as its first record from Vietnam and the Pacific Ocean. A representative of the family Mactridae is firstly reported as a host for pontoniine shrimps and a new host for N. cardiodytes.
