Polydora triglanda Radashevsky & Hsieh 2000

Intertidal to 8 m depth.

A moderate-sized gonochoristic Polydora species boring into mollusc shells and building mud tubes on soft bottoms. Body pigmentation absent. Black bands present on palps in large individuals with more than 60-100 segments. Prostomium incised anteriorly. Eyes, up to 6, usually present. Caruncle reaching end of segment 3; median antenna present. Posterior notopodia with only capillaries. Segment 5 with dorsal superior and ventral capillaries; major spines falcate, with lateral flange, alternating with pennoned companion chaetae. Branchiae from segment 7 usually to end of body. Pygidium disclike or cup-shaped with dorsal gap. Glandular pouches from segment 7, largest in segments 7-9 and drastically smaller in following segments.

West Pacific Ocean, Taiwan: coasts of East and South China seas, and of Taiwan Strait.

The species bores into the shells of the oyster Crassostrea gigas (Thunberg) (the holotype is a boring form), and also inhabits mud tubes on soft bottoms and on aggregations of the mussel Mytilopsis sallei (Recluz), occurring intertidally and shallow subtidally in brackish-water environments.