Trichodinid ectoparasites (Ciliophora: Peritrichida) from the gills of mariculture molluscs in China, with the descriptions of four news species of Trichodina Ehrenberg, 1838.

Four new species of the genus Trichodina, found on gills of marine molluscs from aquaculture beds off the coast of Qingdao (Tsingao), China, are described: T. chlamydis n. sp. from Azumapecten (Chlamys)farreri (Pectinidae), T. sinonovaculae n. sp. from Sinonovacula constricta (Solenidae), T. liana n. sp. from Solen (Plectosolen) gracilis (Solenidae) and T. meretricis n. sp. from Meretrix meretrix (Veneridae). The descriptions presented here include morphometric data obtained from examinations of specimens prepared using the wet silver nitrate and protargol-impregnation techniques. Comparisons with closely related species are provided for each of the four.