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| Pararosa vigarae Junoy & Verdes, in Verdes, Gracia-Sancha, Pérez-Dieste, Conejero, Campos, Leiva, Taboada, Riesgo et Junoy, 2025. Accordion worm | gusano acordeón || DOI: doi.org/10.1098/rsos.250313 |
Abstract
Ribbon worms (Nemertea) are a less-known group of invertebrates, specially challenging for taxonomic studies due to the scarcity of external morphological features. As a consequence, the number of known nemertean species might represent just a small fraction of the true diversity of the phylum. The present study increases the number of known ribbon worm species with the description of the accordion worm Pararosa vigarae sp. nov., a new genus and species of Heternonemertea from the northwest coast of Spain. We performed molecular phylogenetic analyses based on partial sequences of 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I (COI) and histone H3 gene markers that indicated the newly identified specimens represent a new genus and species of heteronemertean in the family Lineidae. We also provide morphological data and images illustrating its unique behaviour, contracting its body into a series of rings similar to an accordion. Our results increase our knowledge on the diversity of an important but often overlooked invertebrate phylum and emphasize the need to combine morphological and molecular data to discover new ribbon worm species and better evaluate the true diversity of the phylum.
Keywords: accordion worm, Heteronemertea, Lineidae, Nemertea, Pararosa vigarae, ribbon worm
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| Live images of Pararosa vigarae sp. nov. (A) Dorso-lateral view of head, showing cephalic slits; (B) anterior end, dorso-lateral view, showing detail of head tip; (C) ventral view of head, the mouth appears as a whitish middle line just behind the cephalic slits; (D) complete specimen with contracted body, showing epidermal rings; (E) dorsal view of complete specimen in a relaxed state, showing epidermal rings. |
PILIDIOPHORA Thollesson and Norenburg, 2003
Class HETERONEMERTEA Coe (1901)
Family LINEIDAE McIntosh, 1874
Genus Pararosa gen. nov.
Diagnosis. Heteronemertean with a single pair of horizontal lateral cephalic slits which posteriorly form deep intramuscular canals; proboscis simple, unbranched; nervous system without neurochord or neurochord cells; dermis thick, glandular region separated from body wall muscles by well-developed connective tissue layer; blood system with cephalic lacunae; frontal sensory organs consisting of three simple ciliated pits located at the tip of the head; eyes absent.
Etymology. The name refers to the type locality of the type species, the ría de Arosa, preceded by the Spanish word par (pair), referring to the two localities where the specimens were collected. The name of the type locality in Spanish is feminine, and thus the new genus name is also feminine.
Type species. Pararosa vigarae sp. nov.
Pararosa vigarae sp. nov. Junoy & Verdes
Diagnosis. Heteronemertean with brown to dark green body, head shape retuse; ocelli absent; contracts into regular rings that persist as annular constrictions when stretched.
Etymology. Named after Rosa Vigara, wife of the senior author, as a gift for their golden wedding anniversary. Specific epithet is a noun, in reference to the last name Vigara.
Common name. Accordion worm.
Spanish common name: gusano acordeón.
Aida Verdes, Carlota Gracia-Sancha, Jacinto Pérez-Dieste, María Conejero, Patricia Alvarez Campos, Carlos Leiva, Sergi Taboada, Ana Riesgo and Juan Junoy. 2025. The Accordion Worm: A New Genus and Species of heteronemertean (Nemertea, Pilidiophora) from Galicia (Spain). R. Soc. Open Sci. 12; 250313. DOI: doi.org/10.1098/rsos.250313 [07 May 2025]