Roseiflexus castenholzii. Roseiflexus castenholzii is related to the Chloroflexaceae, a family of anoxygenic phototrophs. However, it differs from other members of that family in that it lacks chlorosomes and bacteriochlorophyll-c. Bacteriochlorophyll-a is the major photosynthetic pigment in Roseiflexus castenholzii.