Nephtys Cuvier, 1817  

Nephtys Cuvier, 1817

Nephtys cf. paradoxa Malmgren, 1874

Voucher. SEA LION: station 53MFB.

Diagnosis. Large species, voucher is the only example of this species collected; complete specimen, about 65mm long and 5mm wide (including parapodia); posteriorly body segments very deeply incised and narrow, assuming shape of bellows of accordion. Prostomium not clearly observed due to partially everted pharynx. Pharynx only partially everted, proximal part smooth, without warts, not wrinkled; distal part not fully observed: distal region with 10 pairs of terminal bifid papillae, subdistal region about 20 rows of conical papillae (number of these per row not established). Jaws not examined. Inter-ramal cirri recurved; from chaetiger 14 where rudimentary, assuming enlarged foliose shape soon after, progressively increasing in size up to chaetiger 37; from chaetiger 38 foliose appearance lost, branchiae as triangular, fleshy lobe, decreasing in size posteriorly, eventually absent from around chaetiger 55. Parapodia unadorned without enlarged lobes; acicular lobes rounded with a conical tip; pre- and postchaetal lobes short; dorsal cirri small, conical; ventral cirri small, conical (refer to images of parapodia for details). Preacicular chaetae cross-barred; postacicular chaetae basally spinulose (otherwise smooth) in anterior parapodia, becoming more stout (often broken off) in posterior parapodia; chaetae and single aciculae amber in colour, chaetae of posterior chaetigers darker in colour. Pygidium present but damaged; a single achateous ring with dorsal annulated fleshy lobe.

Remarks. The characters observed in specimens collected from FI agree well with Nephtys paradoxa Malm, 1874 (type locality from Northern Europe Koster, Bohuslän, Sweden), which has been recently re-described by Ravara et al. (2010). Currently, it is considered cosmopolitan and there is a need for molecular analysis to resolve its status (see comments in Ravara et al., 2010 for details). Some subtle morphological differences observed between Northern European species (as re-described by Ravara et al. (2010) and Falkland Island specimen are summarised in table below.