<jats:p>A Chl <jats:italic>f</jats:italic>‐containing filamentous cyanobacterium was purified from stromatolites and named as <jats:italic>Halomicronema hongdechloris</jats:italic> gen., sp. nov. after its phylogenetic classification and the morphological characteristics. <jats:italic>Hongdechloris</jats:italic> contains four main carotenoids and two chlorophylls, <jats:italic>a</jats:italic> and <jats:italic>f</jats:italic>. The ratio of Chl <jats:italic>f</jats:italic> to Chl <jats:italic>a</jats:italic> is reversibly changed from 1:8 under red light to an undetectable level of Chl <jats:italic>f</jats:italic> under white‐light culture conditions. Phycobiliproteins were induced under white light growth conditions. A fluorescence emission peak of 748 nm was identified as due to Chl <jats:italic>f</jats:italic>. The results suggest that Chl <jats:italic>f</jats:italic> is a red‐light inducible chlorophyll.