Eumonostilifera Chernyshev, 2003

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 : 147

Suborder Eumonostilifera Chernyshev, 2003

Most of the collected nemertean specimens belong to eumonostiliferous hoplonemerteans. Nine species in three genera are here described as new to science, including two species from the northeastern Pacific outside Costa Rica. In addition, sequences were obtained for two more species that are not described here due to lacking histological material. Five Costa Rican and the two NE Pacific species can be attributed to the clade Oerstediina , whereas the remaining four species group with the Amphiporina clade ( Fig. 7 ).

The first undescribed species is represented by six small (6–8 mm long), bright orange to red specimens (SIO-BIC N259) that have one pair of dorsal, V-shaped cephalic furrows ( Fig. 8I ). This species is sister to two unidentified eumonostiliferans from the depths of the Vema Fracture Zone (ca 5000 m). Together with Abyssonemertes kajiharai Chernyshev & Polyakova, 2017 they form a well-supported clade ( Fig. 7 ). Interspecific p-distances within this clade based on the COI gene vary between 11% and 14%. The second undescribed species (SIO-BIC N109) is represented by one large specimen ( Fig. 8O ) that shares a clade with several species of Paranemertes Coe, 1901 , Tortus tokmakovae Chernyshev, 1991 , and two species of Amphiporus Ehrenberg, 1831 ( Fig. 7 ). The exact position within this clade cannot be fully resolved. Cratenemertea Chernyshev, 2003 were not represented in the samples.

Figures

Fig. 7. Maximum likelihood (ML) tree for the monostiliferan supermatrix based on the concatenated four gene dataset (16S, COI, 18S, H3). 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. Sonnenemertes cantelli Chernyshev, Abukawa & Kajihara, 2015 and Micrura callima Sundberg & Gibson, 1995 were used for outgroup rooting. Specimens belonging to new species are given in bold. Specimen-ID, sampling locality, and depth (for deep-sea species) are provided.

Fig. 8. Live images of eumonostiliferous hoplonemerteans collected along the Costa Rica margin and the NE Pacific. A. Chernyshevia escarpiaphila sp. nov., paratype (SIO-BIC N112). B. Chernyshevia escarpiaphila sp. nov., paratype (SIO-BIC N266). C. Octocoral Paragorgia sp. (SIO-BIC Co3054) with several specimens of Alvinonemertes dariae sp. nov., holotype (arrows; ex SIO-BIC N262). D. Alvinonemertesdariaesp.nov.,holotype(exSIO-BICN262).E.Antipathariancoral(SIO-BICCo3031) with specimens of Alvinonemertes dagmarae sp. nov., holotype (SIO-BIC N260). F. Alvinonemertes christianeae sp. nov., holotype (SIO-BIC N253). G. Alvinonemertes claudiae sp. nov., holotype (ex SIO-BIC N231). H. Alvinonemertes tatjanae sp. nov., holotype (SIO-BIC N119). I. Eumonostilifera (SIO-BIC N259). J–L. Tetrastemma sundbergi sp. nov., holotype (SIO-BIC N256) whole animal (J), dorsal view of head (K), and ventral view of head (L). M. Tetrastemma polyakovae sp. nov. (MZUCR Nemertea Collection MZUCR-101-01).N. Tetrastemma polyakovae sp. nov., holotype (SIO-BIC N258), with everted proboscis. O. Eumonostilifera (SIO-BIC N109).