Caulleriella magnaoculata Hartmann-Schroder 1962

Caulleriella magnaoculata Hartmann-Schröder, 1962

Figure 26

Caulleriella magnaoculata Hartmann-Schröder, 1962: 139–140, figs. 107–109.

Material examined. Peru, Isla Santa, Bahia Coisco, north of Ghimbote, 9 m in muddy shell sediment, holotype (ZMH-P-15040).

Description. Holotype 9.5 mm long, 0.8 mm wide for 125 setigerous segments; posteriormost segments appears to be regenerating (Fig. 26C). Body surface at a higher magnification densely covered with prominent granular spots, most likely subdermal glands.

Prostomium conical, tapering to rounded apex (Fig. 26 A–B); two large pigmented nuchal organs present, best seen ventrally (Fig. 26 A–B), these not eyespots. Peristomium with three annular rings best seen laterally (Fig. 26 A–B); first ring encompassing mouth and extending dorsally; second ring with secondary grooves across dorsum (Fig. 26A); third ring merging indistinctly with dorsum between parapodia of first setiger and carrying dorsal tentacles posteriorly (Fig. 26A); dorsal tentacles therefore arising more or less at same level as first pair of branchiae on setiger 1 (Fig. 26 A–B); second and third peristomial rings with oval-shaped dorsal crest crossed by 5–6 narrow grooves (Fig. 26A).

Setiger 1 and following segments of anterior and middle segments short, with notopodia dorsally elevated as shoulders above smooth, broad dorsum. Branchiae located on medial edge of parapodia well separated from notosetae fascicles (Fig. 26A). Branchiae or their scars easily observed on anterior segments to about setiger 30, thereafter none observed. Neuropodia widely separated from notopodia (Fig. 26 B–C), with two notopodia and two neuropodia located at four corners of body as observed in cross section. Posteriorly, individual segments not as short, but not rounded or moniliform.

Parapodia reduced to simple mounds from which setae arise. Notosetae include 8–10 simple capillaries on the first 35–36 setigers; following notopodia with additional 1–2 hooks; in posterior notopodia capillaries reduced to three and with hooks increasing to five per notopodia. The first nine neuropodia with up to eight capillaries; acicular hooks begin on setiger 10, with three hooks, increasing to five per neuropodium in middle and posterior segments; in far posterior segments hooks increase to nine per neuropodium accompanied by only 1–2 capillaries. Individual hooks with bidentate tips with a thick main fang and short, pointed apical tooth (Fig. 26D).

Posteriormost 23 segments appear to be regenerating with the last 12 segments bearing only 1–2 bidentate hooks; notosetae entirely absent. Pygidium short, rounded, without appendages (Fig. 26C).

Remarks. Caulleriella magnaoculata is readily recognized by the shape and arrangement of the pre-setiger region, the large pigmented nuchal organs (not eyespots as reported in the original description), and the form and distribution of the hooks. In having three annular rings on the peristomium and large “eyespots”, C. magnaoculata is similar to C. chilensis Carrasco, 1977 from Concepción Bay, Chile. The two species differ significantly in that C. chilensis, here raised to full species status, has no peristomial dorsal crest, no capillaries among the posterior neuropodial hooks and there is a distinct sheath on the convex side of the shaft of the hooks that extends forward forming the apical tooth. In contrast, C. magnaoculata has a well-developed peristomial dorsal crest, 1–2 capillaries occur with the posterior neuropodial hooks, and the apical tooth of the hooks is an extension of the shaft, not a separate sheath. It is likely that the large “eyespots” of C. chilensis, like those of C. magnaoculata, are actually pigmented nuchal organs; this cannot be confirmed, however, without examining specimens.

Distribution. Off Peru, 9 m.