A gram-negative, budding, catalase negative, oxidase positive and non-motile bacterium (MBLW1T) with a complex endomembrane system has been isolated from a freshwater lake in southeast Queensland, Australia. Phylogeny based on 16S rRNA gene sequence analysis places the strain within the family Planctomycetaceae , related to Zavarzinella formosa (93.3 %), Telmatocola sphagniphila (93.3 %) and Gemmata obscuriglobus (91.9 %). Phenotypic and chemotaxonomic analysis demonstrates considerable differences to the type strains of the related genera. MBLW1T displays modest salt tolerance and grows optimally at pH values of 7.5–8.0 and at temperatures of 32–36 °C. Transmission electron microscopy analysis demonstrates the presence of a complex endomembrane system, however, without the typically condensed nucleoid structure found in related genera. The major fatty acids are 16 : 1 ω5c, 16 : 0 and 18 : 0. Based on discriminatory results from 16S rRNA gene sequence analysis, phenotypic, biochemical and chemotaxonomic analysis, MBLW1T should be considered as a new genus and species, for which the name Tuwongella immobilis gen. nov., sp. nov. is proposed. The type strain is MBLW1T (=CCUG 69661T=DSM 105045T).