Terebellides gracilis Malm 1874

• Main Authors: Parapar, Julio, Moreira, Juan, Helgason, Gudmundur V.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2011
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Polychaeta; Terebellida; Trichobranchidae; Terebellides; Terebellides gracilis; Iceland
• Online Access: https://doi.org/10.5281/zenodo.5667031; http://treatment.plazi.org/id/8F4F706BFFC2EC46FF4109E49FA9F826

Terebellides gracilis Malm, 1874 Figures 8−10, 13 c Terebellides gracilis Malm 1874: 100. Terebellides williamsae – Jirkov 1989: 124. Jirkov 2001: 529, figs. 1–4. Material examined. A total of 357 specimens (11.48% of total) were obtained in 95 BIOICE samples. BIOICE sample 2619 (three specimens in two SEM stubs IMNH 24931 and IMNH 24932; 67º16'86''N; 16º37'77''W, 600 m). Additional material examined. Type material of T. gracilis . Göteborgs Naturhistoriska Museum (Holotype, GNM Polych 641), Hågarnsskären, Bohuslän. Occurrence. Present in a wide range of depths and temperatures at both sides of Iceland. Depth range: 68 to 2076 m; temperature range: -0.6 to 7.0ºC. Redescription based on holotype. Complete specimen of 32 mm in length and 2.5 mm in width in its widest part; body tapering posteriorly with segments increasingly shorter and crowded towards pygidium. Prostomium compact; tentacular membrane surrounding the mouth and provided with buccal tentacles with expanded tips. First segment forming an expanded structure below tentacular membrane (Fig. 8, 9 a). Branchiae arising as a single structure from segment 3, consisting of a single mid-dorsal stalked structure made up of two pairs of lobes of same length and fused in about one third of length; anterior projection (fifth lobe) present. Posterior region of lobes with pointed projection. Both sides of branchial lamellae provided with several tufts of cilia (Fig. 9 b–c). Lateral lappets on segments 3–7 (chaetigers 1–5) (Fig. 9 a). One large nephridial papilla on each notopodium of chaetigers 4–5 (Fig. 9 d), difficult to see in holotype, with the appearance of a buttonhole (Fig. 9 e–f). Eighteen pairs of notopodia (segments 3–20), compact, rectangular and increasing in size from first to sixth chaetiger. Thoracic neuropodia as sessile pinnules; present from chaetiger 6 (segment 8) to pygidium. Notochaetae of first chaetiger less numerous than notochaetae of subsequent notopodia. All notochaetae long capillaries. Neuropodial uncini in single rows throughout. First ...