Complete chloroplast genomes of two closely related diatoms, <i>Nitzschia nienhuisii</i> and <i>Epithemia catenata</i>

We report the complete chloroplast genomes of two closely related taxa, <i>Nitzschia nienhuisii</i> and <i>Epithemia catenata</i>. The plastids share 96.85% nucleotide similarity and exhibit similar genomic structure. The <i>N. nienhuisii</i> plastome is 128,415 bp with 129 protein-coding genes, whereas <i>E. catenata</i> plastome is 140,525 bp with 130 protein-coding genes, including a duplicated <i>psaJ</i> in the inverted repeat. Both genomes encode 30 tRNAs, one tmRNA, six rRNAs, and two pseudogenes (<i>tyrC</i> and <i>ycf42</i>). The larger <i>E. catenata</i> genome likely reflects 12 unique ORFs. Maximum likelihood phylogenetic analysis supports a close relationship between these taxa.