Ophelina cf. abranchiata (NHM_1769) Fig. 18 A–E

Material examined.

NHM_1769 NHMUK ANEA 2019.7148, coll. 11 Mar. 2015, 12°10.43N, 117°11.57W, 4045 m http://data.nhm.ac.uk/object/8a2cbe4f-277d-4355-a34f-0b53c797bef0.

Description.

This species is represented by a single specimen, in reasonable condition, but anal tube is missing. Small species, 5.3 mm long and 0.3 mm wide; the exact number of chaetigers is difficult to establish, but at least 16 counted, although 17 may be present.

Body cylindrical and smooth without distinct annulation (Fig. 18A, B). Preserved specimen yellow in ethanol; live specimen translucent, with yellow gut (Fig. 18A). Ventral and lateral grooves distinct along whole length of body. Anterior and posterior-most chaetigers slightly shorter than mid-body chaetigers.

Prostomium elongate, conical with small acute terminal palpode (Fig. 18C). Eyes not observed. Nuchal organs rounded, laterally on posterior part of prostomium. Peristomium indistinct. Anterior prechaetigerous region elongated, number of achaetous segments unknown (no SEM). Parapodia rudimentary, biramous, embedded in lateral grooves; no distinct pre- or postchaetal lobes.

Chaetae all slender, smooth capillaries (Fig. 18D), appear in small numbers in both rami, often broken off entirely. Notochaetae mostly longer than neurochaetae.

Branchiae absent. Anal tube not observed. Shirlastained specimens without distinct pattern (Fig. 18E).

Genetic data.

GenBank MN217433 for 16S, MN217501 for 18S and MN217520 for COI. In our phylogenetic analyses it is part of a well-supported clade with Ophelina ganae sp. nov., Ophelina cf. abranchiata (NHM_2017) and at least two other abranchiate opheliids (Fig. 23).

Remarks.

Please refer to section "General comments on Ophelina abranchiata and similar morphotypes" above and remarks for Ophelina ganae sp. nov.