Filamoeba sinensis sp.n., a second species of the genus Filamoeba Page, 1967, isolated from gills of Carassius gibelio [Bloch, 1782]

Filamoeba sinensis, a new species of amphizoic amoeba isolated from the gills of Carassius gibelio (Bloch, 1782) sampled in Hubei Province, China, is described. Both morphology and SSU rRNA gene sequences were employed tocompare this species with Filamoeba nolandi Page, 1967, the type and only species of the genus. Trophozoites differ from F. nolandi in having robust multipolarly branched pseudopodia. A less pronounced hyaloplasmic zone produces a lower number of filiform subpseudopodia. The greatest dimensions of extended trophic forms reach 40-50 μm. Cysts, with a relatively thick and homogeneous wall, are smooth and free of pores. The diameter of rounded cysts ranges from 14 to 20 μm. Cristae of mitochondria are tubular. They are arranged in parallel or irregular mutual positions, their anastomoses or branches were not observed. Phylogenetic analysis revealed a close relationship to F. nolandi.