A New Species of Bathyal Nemertean, <i>Proamphiporus</i> <i>kaimeiae</i> sp. nov., off Tohoku, Japan, and Molecular Systematics of the Genus (Nemertea: Monostilifera)

Abstract

The monostiliferous hoplonemertean Proamphiporus kaimeiae sp. nov. is described based on a single specimen collected from the bottom of the Northwest Pacific, 262 m deep, off Tohoku in Japan, by use of a remotely operated vehicle during a cruise organized by Tohoku Ecosystem-Associated Marine Sciences (TEAMS) research project in 2019. The position of the cerebral organs in the new species, being posterior to the proboscis insertion, is unusual for Eumonostilifera, which is one of the diagnostic traits of the so-far monospecific Proamphiporus Chernyshev and Polyakova, 2019, and Amphiporus rectangulus Strand, Herrera-Bachiller, Nygren, and Kånneby, 2014. The latter is herein transferred to Proamphiporus to yield a new combination, Proamphiporus rectangulus comb. nov., based on the reported internal morphology. Molecular phylogenetic analyses based on 16S rRNA, cytochrome c oxidase subunit I, 18S rRNA, 28S rRNA, and histone H3 genes placed P. kaimeiae in a clade comprised of Proamphiporus crandalli Chernyshev and Polyakova, 2019 and Proamphiporus rectangulus.

At the edge of the sea: the supralittoral nemertean, Acteonemertes orientalis sp. nov. (Nemertea: Eumonostilifera: Plectonemertidae) from Japan

“…The value was comparable with the 5% barcoding gap commonly used to differentiate nemertean species (e.g. Hao et al 2015;Sundberg et al 2016;Kajihara et al 2018;Sagorny et al 2019;Hookabe et al 2020Hookabe et al , 2021Hookabe et al , 2022. The intraspecific COI divergence between a specimen collected from Tsuruga and another from Shimonoseki was 0.10% in uncorrected p-distance.…”

“…DNA extraction, amplification and sequencing followed Hookabe et al (2020). Multi-locus phylogenetic analyses were performed using partial sequences of two mitochondrial ( 16S , 442 bp; COI , 617 bp) and three nuclear gene markers ( 18S , 1704 bp; 28S , 1804 bp); for outgroup taxa, three GenBank entities of Amphiporina ( Amphiporus lactifloreus (Johnston, 1828), Geonemertes pelaensis Semper, 1863, Malacobdella grossa (Müller, 1776)), Cratenemertea ( Nipponnemertes ogumai (Yamaoka, 1947) and N. pulchra (Johnston, 1837)) were used (Table 3).…”

First eumonostiliferous nemertean from the Nishi-Shichito Ridge, Genrokunemertes obesa gen. et sp. nov. (Eumonostilifera, Nemertea)

“…DNA extraction and PCR amplification were performed following Hookabe et al (2020) . After purification with EDTA/ethanol precipitation, products of terminator reactions were sent to GENEWIZ (Tokyo, Japan) for nucleotide sequencing.…”

“…Prior to the concatenation, tree topology of each gene was confirmed that there are no significant discrepancies between different nucleotide markers in regard to the relevant tree topology in this study. Sequence alignment, trimming of ambiguous sites, model selection, and phylogenetic analyses were conducted following Hookabe et al (2020) .…”

“…Nemerteans (or ribbon worms) are usually marine, benthic invertebrates, inhabiting intertidal to hadal depths ( Chernyshev & Polyakova, 2018 ). Although about 1,300 species have been recognized in the phylum ( Kajihara, 2017 ), dozens of species have been turned out to be new to science in five years (e.g., Chernyshev & Polyakova, 2018 ; Chernyshev & Polyakova, 2019 ; Hookabe et al, 2020 ; Hookabe, Kohtsuka & Kajihara, 2021 ; Kajihara, Ganaha & Kohtsuka, 2022 ). In particular, benthic fauna of deep-sea nemerteans at great depths exceeding 1000 m is not well understood; currently, only 19 species were reported ( Chernyshev, 2013 ; Chernyshev & Polyakova, 2019 ).…”