Heterospio aruba new species Figure 4 urn:lsid:zoobank.org:act: AF37BD81-964C-4E9B-B56C-36A5771C9BFF Material examined. (3 specimens) Caribbean Sea, off Island of Aruba, R / V Alpha Helix, Cruise CARIB I, Sta. ND-16, 26 Jun 1977, dredge, 12.506°N, 70.045°W, 30 m, holotype (USNM 1673074), 2 paratypes (USNM 1673075). Description. All three specimens incomplete. Body elongate, narrow; fragments with 11–13 setigers, nine anterior thoracic setigers with first eight crowded, each about four times wider than long, followed by an elongated setiger 9 about 3.5 times longer than each of first eight setigers (Fig. 4A–B). Following abdominal segments each about as long as entire thoracic region. Thoracic segments 1–9 with typical dorso-lateral setal fascicles confined to localized parapodia; these transitioning from setiger 10 to abdominal segments where setae arise from long transverse parapodia resulting in broad cincture-like fascicles or rows mostly surrounding anterior margin of each segment, with dorsal and lateral parapodial gaps. Dorsal surface relatively smooth along entire body; mid-ventral surface of setigers 1–8 with low ridge extending posteriorly from mouth over peristomium to about setiger 8 (Fig. 4B); ventral surface of setiger 9 and abdominal segments smooth, similar to dorsal surface. Holotype (USNM 1673074) largest fragment, with 13 setigers, 5.8 mm long, 0.4 mm wide across thorax and 0.45 mm wide across abdominal segments. Larger paratype with 11 setigers, 3.93 mm long, 0.29 mm wide across thorax and abdomen; smaller paratype long, thin, threadlike, with 12 setigers, 4.36 mm long, 0.12 mm wide across thorax and 0.07 mm wide across abdominal segments. Color in alcohol light tan. Pre-setiger region triangular in shape, about as long as first three thoracic setigers (Fig. 4A–B). Prostomium triangular, wide at base, tapering to narrow rounded tip; eyespots absent, nuchal organs narrow slits along posterior margin (Fig. 4A). Peristomium with two dorsolateral rings dorsally separated by groove; no dorsal ...