The classification of species originally assigned to the marine red algal genus Coeloseira G.J. Hollenberg remains univestigated using molecular data. Paired-end 36 bp Illumina sequences (Illumina Inc, San Diego, CA) were generated from a specimen of Coeloseira compressa G. J. Hollenberg and used to assemble the partial mitochondrial and complete plastid genomes. The mitogenome is 25,391 bp in length and contains 46 genes, and the plastome is 176,291 bp with 233 genes. Both organellar genomes show high gene synteny with previously published Florideophyceae. Comparison of organellar and nuclear phylogenetic markers ( rbc L, CO1, LSU) of C. compressa to other genera in the Champiaceae supports its removal from Gastroclonium Kützing and the reinstatement of the name Coeloseira compressa .