Nereis, Linnaeus, 1758

Hsueh, Pan-Wen, 2020, New species of Nereis (Annelida, Polychaeta, Nereididae) from Taiwanese waters, Zootaxa 4802 (1), pp. 1-31 : 27-29

Nereis sp. B

Figs 20A–C, 21A–G

Material examined. One specimen ( NMNS 8174-037 ), CP373 (24º16.287´N 122º11.647´E), offshore from eastern Taiwan, bathyal benthic soft bottom, 2233–2551 m deep, 26 August 2006 .

Brief description. Incomplete, posterior end missing, remaining body length 19.0 mm with 31 chaetigers, maximum width 3.0 mm on chaetiger 7, excluding parapodia; beige in alcohol (Fig. 20A). Prostomium wider than long, lateral antennae antero-lateral; palpophores globose, palpostyles conical, four pairs of tentacular cirri, longest one reaching chaetiger 4 (Fig. 20A). Eyes not observed. Apodous anterior segment about 1.4 times as long as chaetiger 1. Pharynx with dark brown jaws, each jaw with 7–8 teeth; I=2, in a longitudinal line; II = 21 (left), 21 (right), in 3 oblique rows; III =37, in 3 transverse rows; IV = 11 (left), 30 (right), in 5 oblique rows; V =0; VI = 7 (left), 5 (right), in a loose cluster; VII / VIII =74, in 5–6 rows (Fig. 20B).

Notopodial dorsal ligules narrow triangular on anterior chaetigers, acute (tip broken off on anterior chaetigers) (Fig. 20C). Dorsal cirri basally attached to dorsal ligules, acute (tip broken off on anterior chaetigers), about 1.5 times as long as dorsal ligules (Fig. 20C). Notopodial prechaetal lobes absent. Notopodial ventral ligules narrow triangular on anterior chaetigers, truncate (Fig. 20C). Neuropodial postchaetal lobes absent. Neuropodial ventral ligules narrow triangular on anterior chaetigers, acute (tip broken off on anterior chaetigers); ventral cirri mid-ventrally attached to ventral edge of parapodia, acute (tips broken off on anterior chaetigers), about as long as ventral ligules (Fig. 20C).

FIG. 20. Nereis sp. B ( NMNS 8174-037): A, anterior body; B, pharyngeal area; C, chaetiger 11, right parapodium, posterior view; D, chaetiger 36, right parapodium, anterior view. (Abbreviations: DC, dorsal cirrus; NeVL, neuropodial ventral ligule; NoDL, notopodial dorsal ligule; NoVL, notopodial ventral ligule; VC, ventral cirrus). Scale: A, B, 1.0 mm; C, 0.25 mm.

FIG. 21. Nereis sp. B ( NMNS 8174-037): A, chaetiger 34, notochaetal homogomph spiniger; B, same, notochaetal homogomph falciger; C, chaetiger 31, notochaetal homogomph falciger; D, chaetiger 34, neurochaetal dorsal fascicle, homogomph spiniger; E, chaetiger 9, neurochaetal dorsal fascicle, long-bladed heterogomph falciger; F, chaetiger 34, neurochaetal ventral fascicle, heterogomph spiniger; G, same, neurochaetal ventral fascicle, medium-sized blade heterogomph falciger. Scale: A, D, F, 0.025 mm; B, C, E, G, 0.01 mm.

Notochaetae present from chaetiger 3 to posterior segments, homogomph spinigers present on anterior chaetigers to mid-body chaetigers (Fig. 21A), homogomph falciger present from chaetiger 28 to mid-body chaetigers, blade bent distally, blunt-tipped, tip of blade sometimes broken off, base with several teeth and serrations (present cases: 10 or 13 teeth) (Fig. 21B, C). Neurochaetae upper fascicle: homogomph spinigers present (Fig. 21D), heterogomph falcigers with serrated long-blade on anterior chaetigers and serrated medium-sized blade on posterior chaetigers (Fig. 21E, F). Neurochaetae ventral fascicle: heterogomph spinigers present (Fig. 21G), heterogomph falcigers with serrated long-blade on anterior chaetigers and serrated medium-sized blade on mid-body chaetigers (Fig. 21E, F).

Distribution. Only known from the bathyal benthic bottom off eastern Taiwan.

Remarks. Morphological similarities and differences between N. sp. A and N. sp. B have been fully discussed in the Remarks sections of N. sp. A. These two species have a unique paragnath pattern on Areas VII & VIII, which are not seen in congeners of new species reported in the present study.