Heteromastus namhaensis sp. nov. A anterior end, left lateral view (holotype, NA00155558) B same, dorsal view C posterior abdominal segments, right lateral view (holotype, NA00155558) D posterior end, dorsal view (holotype, NA00155558) E abdominal short-shafted hook, frontal view. F thoracic long-shafted hook, lateral view G abdominal short-shafted hook, lateral view. Abbreviations: ac, anal cirrus; cc, capillary chaetae; Ch, chaetiger; gp, genital pore; hh, hooded hooks; lo, lateral organ; mf, main fang; neu, neuropod; no, notopod; per, peristomium; pro, prostomium; prob, proboscis; pyg, pygidium.