AUTHOR=Abato Jamael C. , Chernyshev Alexei V. , Hookabe Natsumi , Tsuyuki Aoi , Kaushik Gauri , Kajihara Hiroshi 

TITLE=Delimiting the polymorphic congeners of the genus Oerstedia Quatrefages, 1864 (Nemertea, Hoplonemertea), and descriptions of three new species from the Northwest Pacific

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=12

YEAR=2024

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2024.1356316

DOI=10.3389/fevo.2024.1356316

ISSN=2296-701X

ABSTRACT=<p>Three new species of the monostiliferous hoplonemertean genus <italic>Oerstedia</italic> Quatrefages, 1864, are herein described using morphological and molecular data—<italic>Oerstedia pseudoculata</italic> sp. nov., from Akkeshi Bay and Oshoro Bay, Hokkaido, Japan, and from Aniwa Bay, Sakhalin, Russia; <italic>Oerstedia rugosa</italic> sp. nov. from Sagami Bay, Misaki, Kanagawa, Japan, and Van Phong Bay, Vietnam; and <italic>Oerstedia viridifusca</italic> sp. nov. from Manazuru, Kanagawa, Japan. As to the external morphology, <italic>O. pseudoculata</italic> sp. nov. can be differentiated from <italic>O. oculata</italic> only by its bright-orange ocelli visible on both sides of the head, and a proboscis pore opening at the ventral tip of the head. These two sister species repeat each other’s color patterns, a phenomenon that can be explained by Vavilov’s law of homologous series. <italic>Oerstedia rugosa</italic> sp. nov. can be identified by its carmine or deep-red to brownish-red body with several longitudinal, intertwined white lines or wrinkles running from the head to the posterior body, and by 17–23 vaguely bordered white bands composed of variedly sized dots encircling the body, arranged at irregular intervals. <italic>Oerstedia viridifusca</italic> sp. nov. can be distinguished from other <italic>Oerstedia</italic> by (<italic>i</italic>) the entire body flecked with minute greenish-brown dots, especially densely on the anterior portion of the dorsal surface, but sparsely on the posterior half of the ventral surface; (<italic>ii</italic>) a collar-like portion encircling the body along the posterior cephalic furrow where the greenish-brown dots are absent; (<italic>iii</italic>) the anterolateral edges of the head lacking the greenish-brown dots; and (<italic>iv</italic>) the ocelli being brownish-orange in color. <italic>Oerstedia phoresiae</italic> (Kulikova, 1987) is reported for the first time from Japan, in addition to its previous distribution record in Russia and in South Korea. Phylogenetic analyses based on the 16S, 18S, 28S ribosomal RNA, cytochrome <italic>c</italic> oxidase subunit I, and histone H3 genes show that the new species are true congeners of the genus <italic>Oerstedia</italic> with <italic>O. pseudoculata</italic> sp. nov. and <italic>O. viridifusca</italic> sp. nov. nested within the clade <italic>Paroerstediella</italic> whereas <italic>O. rugosa</italic> sp. nov. in the clade <italic>Oerstedia</italic>. This taxonomic work emphasizes the importance of DNA barcode sequence in the taxonomy and systematics of the polymorphic congeners of the genus <italic>Oerstedia</italic>.</p>