| Summary: | Chaetozone elakata new species Figures 1–3 Material examined. Northeast Atlantic Ocean, offshore France, Bay of Biscay. R/ V Côtes de la Manche Sta. JERICO-8, 45°38′55″N, 01°45′47″W, coll. 28 October 2016, 0.25m ² Hamon grab, 62 m, holotype (MNHN-IA- TYPE 1800), 3 paratypes (MNHN-IA-TYPE 1801), 2 Paratypes, SEM (MNHN-IA-TYPE 1802) and 7 paratypes (MCZ 143234). Description. A moderate-sized species with elongate body and conspicuous bulge in middle of thoracic region imparting distinct fusiform shape to anterior end (Figs. 1 A, 3A, D). Anterior segments crowded, about four times as wide as long (Fig. 1 A), then becoming longer, but still about twice as wide as long in middle body segments (Fig. 3 A, D). Posterior segments narrowing, with parapodia becoming modified, with deep grooves between individual segments (Figs. 1 C, 2F) and parapodia elevated with thin membranes bearing spreading fascicles of spines and alternating capillaries producing a prominent armature (Fig. 2 B–C). Holotype (MNHN-IA-TYPE 1800) complete, 45.4 mm long, 0.64 mm wide anterior to bulge, 1.01 mm across bulge, 0.65 mm posterior to bulge, with 111 setigerous segments; complete paratype an ovigerous female (MCZ 143234) 33 mm long, 0.4 mm wide anterior to bulge, 0.65 across bulge, 0.52 mm posterior to bulge, with 117 setigerous segments. Other complete paratypes with 92–104 setigerous segments. Most specimens with distinct dorsal groove, in expanded segments (Figs. 1 A, 3B), absent in some specimens (Fig. 3 A); weak depression present on individual segments along most of venter; absent in posterior segments. Color in alcohol light tan with no apparent pigment on body; numerous segmental subdermal glands visible under a coverslip at about 63x magnification; these stain with Methyl Green imparting distinct patterns (see below). Prostomium triangular, narrowing to rounded tip (Fig. 1 A–B); nuchal organs reduced to thin slits at posterior margin of prostomium, best seen with SEM (Fig. 2 A); eyespots absent. Peristomium relatively narrow, ...
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