Heteronemertea Bürger, 1892

Sagorny, Christina, Döhren, Jörn von, Rouse, Greg W. & Tilic, Ekin, 2022, Cutting the ribbon: bathyal Nemertea from seeps along the Costa Rica margin, with descriptions of 2 new genera and 9 new species, European Journal of Taxonomy 845 (1), pp. 132-174 : 146

Order Heteronemertea Bürger, 1892

One single heteronemertean specimen (SIO-BIC N254), representing a member of Lineidae McIntosh, 1873 , was collected in associated with experimentally deployed wood at 1887 m depth at the Jaco Scar methane seep. This specimen is 45 mm long and has a diameter of 5 mm. The body is translucent and of pale whitish coloration. It possesses a long caudal cirrus ( Fig. 3C ). It forms a clade with three undescribed lineids collected in the abyssal vicinity of the Kuril-Kamchatka Trench ( Fig. 5 ). Based on the concatenated analysis, this clade cannot be attributed to any of the known heteronemertean genera. Pairwise distances of the COI gene between Lineidae sp. SIO-BIC N254 and those three heteronemerteans are around 14%. Since no material for histological sectioning is left, we do not describe this species herein, also due to the convoluted taxonomy of Lineidae , that needs extensive revision and goes beyond the scope of our study. However, the sequence data is published in order to facilitate future studies on deep-sea Lineidae .

Figures

Fig. 3. Live images of palaeonemerteans, heteronemerteans, and polystiliferous hoplonemerteans collected along the Costa Rica margin. A. Tubulanus cf. lutescens (SIO-BIC N107) (Palaeonemertea). B. Dorsal surface of head region of Tubulanus cf. lutescens (SIO-BIC N233). C. Lineidae (SIO-BIC N254) (Heteronemertea). D–E. Reptantia (SIO-BIC N263) (Polystilifera) dorsal (D) and ventral view (E).

Fig. 5. Maximum likelihood (ML) tree for the heteronemertean supermatrix based on the concatenated four gene dataset (16S, COI, 18S, H3). Numbers beside nodes indicate support values. Black circles indicate nodal support of 100/100/1.0; asterisks indicate nodal support of either 100/ or /1.0. Alternative branches found in the BI analysis are given as blue dotted lines. Tubulanus polymorphus Renier, 1804 and Carinoma mutabilis Griffin, 1898 were used for outgroup rooting. The specimen found at the Costa Rica margin is given in bold. Specimen-ID, sampling locality, and depth (for deep-sea species) are provided.