Dysponetus sp. 1

Watson, Charlotte, Chivers, Adam J., Narayanaswamy, Bhavani E., Lamont, Peter & Turnewitsch, Robert, 2014, Chrysopetalidae (Annelida: Phyllodocida) from the Senghor Seamount, north-east Atlantic: taxa with deep-sea affinities and morphological adaptations, Memoirs of Museum Victoria 71, pp. 311-325 : 317

Dysponetus sp. 1

Material examined. Senghor Seamount, 17º12.30'N 21º57.70' W, North transect, Core 1509 #01, shelly sand, 133 m, coll. SAMS, Oct 2009, SMF 22963 .

Description. One anterior end of 9 segments, 1.2 mm long, 0.9 mm wide. Very small bodied, body fragmented after pharynx level. Prostomium quadrate, with two pairs of large, entire eyes; two small lateral antennae visible on anterior edge of prostomium, median antenna broken, two ventrolateral palps with subulate tips, moderate length. Elongate, single lobe present on posterior margin of mouth; elongate pharynx with pair of slender, red-brown stylets; everted proboscis with ring of small papillae.

Anterior segments: very reduced, achaetose segment I with 2 pairs of long dorsal cirri, ventral cirri bases evident; segment II biramous with notochaetae, long dorsal cirri, neurochaetae, no ventral cirri; notopodia of segment III with notochaetae, dorsal cirri, neuropodia with neurochaetae, small, subulate ventral cirri, not extending past neuropodial tip.

Notochaetal spines moderate length with two rows of spinelets; compound neurochaetae with slender shafts, slender, finely serrate blades, minute blade tips unidentate to bifid.

Remarks. Overall anterior end and chaetal characters agree between the shallow and deep Dysponetus individuals, but the smaller Dysponetus sp. 1 possesses two pairs of large red eyes, and all D. caecus material from both shallow and deep waters have been described in the literature as lacking eyes.

The only dysponetid described with eyes from the NE Atlantic is Dysponetus joeli Olivier, Lana, Oliveira & Worsfold, 2012 recorded from the English Channel in a maerl, shallow-water habitat. Without examining original Dysponetus joeli material, it is not possible to compare the single Senghor Seamount specimen based on the poorly preserved material figured and described in the literature.

Habitat. Dysponetus sp. 1 is found at 133 m at Senghor Seamount among coarse sediments.