A histology-free description of Tetrastemma cupido sp. nov. (Nemertea: Eumonostilfera) from Sagami Bay, Japan

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.…”

Molecular Phylogeny of the Genus Nipponnemertes (Nemertea: Monostilifera: Cratenemertidae) and Descriptions of 10 New Species, With Notes on Small Body Size in a Newly Discovered Clade

“…With the advent of molecular tools-DNA barcoding and molecular phylogeny-in monostiliferan systematics (e.g., Andrade et al, 2012;Kvist et al, 2014;Kvist et al, 2015;Leasi et al, 2016;Hookabe et al, 2020;Hookabe et al, 2021), we are now in a position to obtain a more accurate picture of the species diversity. Some of the diagnostic characters traditionally used in monostiliferan taxonomy are often ambiguous and thus need to be revisited with molecular phylogeny.…”

Three new species in Tetrastemma Ehrenberg, 1828 (Nemertea, Monostilifera) from sublittoral to upper bathyal zones of the northwestern Pacific

“…A histology-free description with DNA barcoding has been progressively introduced to nemertean systematics in the past decade (e.g., Kajihara 2015 ; Gonzalez-Cueto et al 2017 ; Simpson et al 2017 ; Kajihara et al 2018 , 2022 ; Chernyshev et al 2020 ; Hookabe et al 2021a , b ; Leiva et al 2021 ; Abato et al 2022 ). This approach has been applied to two cases, one of which is a description of species with internal characters interspecifically differentiated and observable without histology (e.g., number of proboscis branches in Gorgonorhynchus Dakin & Fordham, 1931 [ Kajihara 2015 ; Hookabe et al 2021a )].…”

“…In the other case, especially when internal morphology is uniform between most species in a genus, a species description has been performed solely based on characters examined in-vivo (shape of head, body coloration and markings, number of eyes, blood color, and stylet apparatus) [e.g., Baseodiscus Diesing, 1850 ( Kajihara et al 2022 ) and Ototyphlonemertes Diesing, 1863 ( Kajihara et al 2018 )]. Recent descriptions of species in the genus Tetrastemma Ehrenberg, 1828, fitting the latter case, have been performed based on characters of living specimens without histological observations ( Chernyshev et al 2020 ; Hookabe et al 2021b ; Abato et al 2022 ).…”