Polychaete species are widely distributed throughout Indo-Pacific and European waters. We collected
Metasychis specimens from the China Seas to report on
Metasychis varicollaris sp. n. and
Metasychis gotoi (Izuka, 1902) in greater detail. Geographic analysis of the potential distribution areas of
M. gotoi indicates that it may be found in most coastal areas of China. The newly discovered species,
M. varicollaris and
M. gotoi, have an overlapping distribution in the northern South China Sea.
Metasychis varicollaris sp. n. is characterized by a crenulated cephalic rim, complete collar on chaetiger 1, a packet-shaped anal funnel, and a spirally-fringed notochaetae with spiral pectinate bands imbricated over the main shaft. Our study provides a taxonomic key to all species of
Metasychis.
