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

Abstract

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 Funiculina, Halipteris, Protoptilum and Distichoptilum, four species each of Umbellula and Pennatula, three species of Kophobelemnon and two species of Anthoptilum, as well as one species of the epi- and mesobenthic genus Virgularia. Seventeen circular genomes ranged from 18,513 bp (Halipteris cf. finmarchica) to 19,171 bp (Distichoptilum gracile) 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 Umbellula has a bipartite genome (∼13 kbp and ∼5 kbp), with good evidence that both parts are circular.

Keywords:

• Gene order
• mitogenome
• multipartite genome
• pennatulacean
• sea pens

Acknowledgements

We would like to thank the crew of RV Celtic Explorer (CE13008, CE14009, CE15009, CE16006), RRS James Cook (JC125) and M/T Paamiut, the pilots of the ROV Holland I and ISIS, Greenland Institute of Natural Resources, and Tony O’Callaghan from Sea Search Ireland for the support of the collection at sea. The authors would like to especially acknowledge Dr. Veerle Huvenne from the National Oceanography Center (UK), the CODEMAP project coordinator, in addition to the CODEMAP2015 team for the invaluable support and effort to collect pennatulacean samples. RH thanks Gary Williams for inspiration and valuable resources. We thank two anonymous reviewers for their extremely constructive comments which have allowed us to improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

RV Celtic Explorer cruises were funded through the Marine Institute’s National Shiptime Program. The JC125 expedition was funded through the ERC Starting Grant project CODEMAP (Grant No 258482) and the NERC MAREMAP National Capability Program. R.H. is supported by Brazilian National Council for Scientific and Technological Development (CNPq) Grant 248444/2013-1 and a NUI Galway Thomas Crawford Hayes Research grant.