Description of the fifth sea pen species that attaches to hard substrates by modifying its peduncle

Almost all sea pens inhabit soft bottoms, but only four species are known to live on rocky substrates. These are all deep-sea species with specialized sucker-like peduncles considered to attach to rocky substrates. Their known distribution is very sparse due to the limited number of reports. In this study, we describe a novel rock-inhabiting sea pen, Anthoptilum gnome sp. nov., from a deep-sea marine protected area in Japan, along with the first report of the mitochondrial genome of a rock-inhabiting species and a rock-inhabiting species from the northwestern Pacific Ocean. The mitogenomic information provides insight into their evolutionary aspect; A. gnome sp. nov. may have acquired the sucker-like peduncle within the phylogenetic constraints in the genus and the sucker-like peduncle may be the character obtained independently in Pennatuloidea.