Sagitella kowalewskii Wagner, 1872

(Figs 1, 11, 12A–B)

Sagitella kowalevskii form A, Wagner, 1872: 342, Fig. A–C [original description, Mediterranean, Bay of Naples].– Uljanin, 1878: 1–32, Pl. I, Fig. 1 [anatomy, morphology and larval development, Mediterranean, Naples and Villefranche-sur-Mer].– Reibisch 1895: 56, Pl. V, Fig. 9 [description, Central Atlantic].–Southern 1910: 29 [distribution, Irish Sea].– Gravier 1911: 517, Figs. 30–32 [description].– Ehlers, 1913: 526, Pl. XXXIX, Fig. 15 [description, Indian Ocean, Antarctic].– Fauvel 1916: 71 [description, Atlantic up to the west coast of Ireland, Mediterranean and Black seas].– Chamberlin 1919: 153 [brief description and distribution, Pacific between the Galapagos and the Tuamotu Islands, Nanga Reva].– Stǿp-Bowitz 1948: 56, Fig. 43 a–e [brief description, South Atlantic].–Uschakov 1955: 114, Fig. 14 [brief description, North Pacific].– Dales 1957: 147, Figs. 56, 57 [brief description, Central Pacific].– Day 1967: 209, Fig. 9.1 c–e [brief description, Agulhas and Mozambique currents, South Africa].– Tebble 1960: 33 [distribution, South Atlantic].

Acicularia virchowii Langerhans, 1877: 727 [original description, Madeira].–Greeff 1878: 51, 1879: 237, Figs 46–48 [description, Canary Islands].

Plotobia paucichaeta Treadwell, 1943: 38, Pl. II, Fig. 26 [original description with distribution, Atlantic and Pacific from 45ºN to 40ºS].

Material examined. Three specimens: ZMMU WS20980 (FA, Et), ZMMU WS20981 (FA), ZMMU WS20982 (Et) .

Description (based on all our material). Body 15.8–20 mm long, 0.5–0.6 mm wide without parapodia, 0.6–1 mm wide with parapodia and cirri, graceful and slender, with 28–30 chaetigers of body trunk. Live worms transparent, with intersegmental dissepiments well visible through body wall; ethanol- and formalin-fixed specimens semitransparent white. Prostomium conical, pointed, with small terminal palpodium and with dorsal thickening above retort organ (Fig. 12A). Nuchal organs as two low semi-circular ridges on dorsal side of prostomium (Fig. 12A). Extended proboscis not observed. Three anteriormost pairs of cirri oval, covering head region. First pair attached near base of palpodium, second pair attached at level of nuchal organs (Fig. 12A). All chaetigers with dorsal and ventral podial cirri. Dorsal cirri rounded with pointed dorsal edge in first third of body, rectangular with pointed dorsal edge in middle of body; three-four last ones narrow, lanceolate. Ventral cirri of same shape as dorsal ones, but slightly smaller. Parapodia from 3 rd –4 th chaetiger, small, conical, uniramous, each with two simple recurved capillary chaetae, and one thick aciculum penetrating through epidermis. Caudal cirri broad, irregularly triangular; supporting hyaline rib closer to outer side of cirrus (Fig. 12B).

Distribution. Cosmopolitan. Type locality: Bay of Naples (Wagner 1872). Central Red Sea (this study).