This study for the first time reported the sessile filter-feeding Ficopomatus cf.macrodon in freshwater in China.Specimen were collected from the stones of a artificial river in the suburbs of Shenzhen(113° 46′ 07.52″ E;22° 43′ 41.91″ N).While dipped the stone in tap water for 20 d,the water tasted brackish.There was a longitudinal ridge on the midline of the tube's coping,and the annulations were not obvious.The length of the polypide was 6.4-8.0 mm.The branchia coronal had 16 gill filaments.The operculum was olivary in shape.The polypide had 7 thoracic segments,and the first capillaceous-like segment had 9-11 collar setae.Thoracic uncinus contained 9 teeth in a single row,47-52 μm in length.Abdominal uncinus contained 11-13 teeth,50-55 μm in width.The length of the ventral chaetae was 506-525 μm.Histology observation showed that the branchia filament,operculum and the surface of collar were constituted by simple columnar epithelium cells.There was a layer of colloid matter on the surface of branchia filament.Mini-sand bestrewed the operculum's coping.Thoracic surface contained numerous secretory cells.Dioecism,with no real germen,each arthromere of mature individual's ventral was filled with dense semen or ovum.The alimentary canal was comprised by mouth,esophagus,intestines and anus.Vertical fascicle on the thoracic dorsal developed well.Chaeto-muscle was carried by the setae,and dorsal blood vessel was on the back of esophagus,big on two sides and narrow on fluctuation.Excretory system had two U-like nephridiums,distributing only in the prothorax,and the excretory pore was in the middle of branchia filament.The brain was above dorsal esophagus,and its transverse section showed a shape of butterfly,with two dorsal horns and two ventral horns filled with dense colloid cells,and inside with some fragmentary collagen.Finally,we compared and discussed modality differences between Chinese specimen and existing species of F.cf.macrodon.