Etymology. It is named ‘rarus’ from the Latin word meaning rare, indicating its low abundance and distribution in the environment.
Brief description. Planktophila rarus MRE-26 (ENA accession number GCA_965268205) was isolated from the epilimnion (0.5m depth) of Římov Reservoir, Czech Republic (date: 2021-04-06) and it is the only isolated representative of the species. It has a complete circular genome with a size of 1,468,350 bp, a GC content of 47.5%, and a coding density of 95.7%. It encodes one rRNA operon and 39 tRNA genes. It encodes for both actinorhodopsin and heliorhodopsin, as well as the capacity to de novo synthesize retinal. It encodes for both oxygenic and anoxygenic parts of the pentose phosphate pathway. It can synthesize most amino acids, being auxotrophic for asparagine. Recruitment analysis indicates a very restrictive distribution, specifically the epilimnetic waters of Římov Reservoir during spring. The closest cultivated species is Planktophila aestivalis MRE-130, having an average nucleotide identity of 86.5%. The Current GTDB classification (r220) is d__Bacteria;p__Actinomycetota;c__Actinomycetia;o__Nanopelagicales;f__Nanopelagicaceae; g__Planktophila; s__.