Type genome is Planktophila lacusMMS-21-148 (GCF_002287925.1), which was isolated via dilution-to-extinction cultivation from Lake Zurich, Switzerland. Curved rods with lengths of 0.41±0.10 μm and diameters of 0.30±0.06 μm. The initial pure culture was lost after a few propagations to fresh medium; no growing culture is available. The initial culture grew well in sterile lake water amended with minimal carbon medium, vitamins and amino acids. Planktophila lacusMMS-21-148 has a genome size of 1.46 Mbp and a genomic GC content of 47.5%. The genome is complete, consisting of a circular chromosome and contains 3 rRNA genes and 41 tRNAs. It is auxotrophic for reduced sulfur sources, betaine, and several vitamins (B1, B5, B7, B12) and possesses rhodopsins. Basis for the assignment is a phylogenomic tree of 476 concatenated protein sequences, phylogenetic analysis of 16S rRNA, 23S rRNA, and rhodopsin genes, as well as average nucleotide and amino acid identities presented in Neuenschwander et al. (2018, ISMEJ, doi: 10.1038/ismej.2017.156). The closest cultivate relatives are Planktophila aquatilis IMCC26103 (GCA_002284875) and Planktophila rubra IMCC25003 (GCA_002284855) with average amino acid identities of 84.1 and 74.4%, respectively, and average nucleotide identities of 77.9 and 72.6%, respectively.