Figure 3
urn:lsid:zoobank.org:act: 5CAAF2EE-99DC-4064-AABD-0C7750F04D49
Material examined. (71 specimens) Northeastern USA, off Nobska Point, Woods Hole, Massachusetts, coll. Oct 1975, N.J. Maciolek, 41°30.86ʹN, 70°39.36ʹW. ca. 5–10 m, holotype (MCZ 161683), 70 paratypes (MCZ 161684).
Description. A moderately sized species, with long narrow body widest in middle segments; holotype complete, with 88 setigers, 21.5 mm long, 0.3 mm wide across anterior setigers, 0.44 mm wide across middle setigers, narrowing again in posterior setigers. Body rounded dorsally, flattened ventrally with shallow mid-ventral groove extending from peristomium to posterior segments (Fig. 3A). Color in alcohol opaque white to light tan; most specimens with light brown cast in middle segments; some specimens with dark brown spots or short bands in variable patterns along body, but not consistent.
Pre-setiger region long, narrow, as long as first 3½ setigers (Fig. 3A–B). Prostomium triangular in dorsal view, tapering to pointed tip (Fig. 3B), relatively narrow in lateral ventral view (Fig. 3A); nuchal organs semicircular grooves on lateral posterior margin; eyespots absent. Peristomium long, narrow, not divided but with well-developed broad dorsal crest (Fig. 3A–B); dorsal tentacles arise from posterior margin (Fig. 3A–B); first branchiae lateral to dorsal tentacles (Fig. 3A–B); second pair of branchiae dorsal to notosetae on setiger 1 and in same location on subsequent setigers (Fig. 3B).
Parapodia reduced, with no distinct podia or postsetal lobes apparent; setae arising directly from body wall. Noto- and neuropodia not widely separated as in related species. Notosetae of first 10–12 setigers all capillaries; hooks first present from setigers 11–13 (13 in holotype). Neurosetae of first 9–10 setigers all capillaries; hooks first present from setigers 10–11 (11 in holotype). Capillaries of both noto- and neuropodia numbering about 8–10 in larger specimens, arranged in two rows with capillaries of first row shorter and thicker than capillaries of second row; notosetae longer than neurosetae (Fig. 3D). Capillaries with broad blades and distinct fimbriated edge with individual fibrils often separated producing the appearance of a serrated edge (Fig. 3E–H). Hooks accompanied by 1–2 capillaries for 1–3 segments, then capillaries entirely absent along body in both noto- and neuropodia (Fig. 3I). Hooks numbering one per noto- or neuropodium through first third of body, then increasing to two and three hooks in middle and posterior setigers. Hooks in noto- and neuropodial fascicles directed toward one another, vis-à-vis (Fig. 3I). Individual hooks with recurved shaft tapering to distinct bidentate apex; main fang directed at about 45° to shaft with short pointed apical tooth; hood and sheath absent. Hooks of neuropodia appearing slightly thicker and more sigmoidally curved (Fig. 3L–M) than those of notopodia (Fig. 3J–K).
Pygidium with two simple lobes; anal cirri absent (Fig 3C).
Methyl Green staining. No pattern.
Remarks. Unlike most shallow-water species of Caulleriella, C. nobska n. sp. has a long narrow body lacking a distinct separation of the thorax and abdomen. The peristomium is unusually long and bears a prominent dorsal crest. In addition, the noto- and neuropodia are only moderately separated from one another. However, the nature of the recurved bidentate hooks is similar to other species where a hood or sheath is lacking.
Caulleriella nobska n. sp. is most similar to C. venefica, another species from the northeastern United States that is widespread on the continental shelf. Both species have a pointed prostomium, an elongate, smooth peristomium with a dorsal crest, and bidentate hooks lacking a crest or sheath. Caulleriella nobska n. sp. differs from C. venefica in having a shorter prostomium, up to three hooks in posterior neuropodia instead of two, and no anal cirri on the pygidium instead of two cirri. In addition, the bidentate hooks of C. venefica as illustrated by Doner & Blake (2006) and as observed in this study, have the main fang at a more acute angle than the 45° angle observed in C. nobska n. sp. and C. venefica may have a single thin capillary seta accompanying the hooks in middle and posterior setigers instead of capillaries being entirely absent in posterior setigers of C. nobska n. sp.
Etymology. The epithet is from the collecting locality off Nobska Point, a promontory in Woods Hole, Massachusetts and the location of a historic lighthouse.
Distribution. Massachusetts, shallow subtidal.