Novel diversity in mitochondrial genomes of deep-sea Pennatulacea (Cnidaria: Anthozoa: Octocorallia).

We present the first documented complete mitogenomes of deep-sea Pennatulacea, representing nine genera and eight families. These include one species each of the deep-sea genera , and , four species each of and , three species of and two species of , as well as one species of the epi- and mesobenthic genus . Seventeen circular genomes ranged from 18,513 bp ( cf. ) to 19,171 bp () and contained all genes standard to octocoral mitochondrial genomes (14 protein-coding genes, two ribosomal RNA genes and one transfer RNA). We found at least three different gene orders in Pennatulacea: the ancestral gene order, the gene order found in bamboo corals (Family Isididae), and a novel gene order. The mitogenome of one species of has a bipartite genome (∼13 kbp and ∼5 kbp), with good evidence that both parts are circular.