Chaetozone curvata Hartmann-Schröder, 1965

Blake, James A., 2018, Bitentaculate Cirratulidae (Annelida, Polychaeta) collected chiefly during cruises of the R / V Anton Bruun, USNS Eltanin, USCG Glacier, R / V Hero, RVIB Nathaniel B. Palmer, and R / V Polarstern from the Southern Ocean, Antarctica, and off Western South America, Zootaxa 4537 (1), pp. 1-130 : 87-88

Chaetozone curvata Hartmann-Schröder, 1965

Chaetozone curvata Hartmann-Schröder, 1965: 219–221 , figs. 213–215; Rozbaczylo 1985: 151; Blake 1996: 289; Montiel 2005: 88, 94.

Material examined. Chile, offshore Valdivia , holotype, Sta. 96, coll. 15 Mar 1960, 39°59.9ʹS, 74°0.15ʹW, silt with fine sand, stones, and little detritus, 260 m ( ZMH P-15050) .

Description. Holotype complete, 11 mm long, 0.5 mm wide, with 85 setigers. Specimen in poor condition, darkly colored, almost black, likely due to having died prior to preservation. Some evidence of pigment granules on anterior segments, these obscured by dark color. Anterior segments narrow, about eight times wider than long; middle segments becoming longer and more rounded, posterior segments cinctured.

Prostomium slender, conical, slightly longer than wide; eyespots absent; nuchal organs not observed. Peristomium with three rings, first narrow, merged with prostomium; second and third rings larger, about equal in size, each about twice as large as following setigerous segments; no dorsal crest, grooves cutting each ring continuing dorsally. Dorsal tentacles arise from posterior margin of peristomium. First branchiae on setiger 1 dorsal to notosetae; subsequent branchiae on following segments in same position; branchiae present along three-quarters of body, absent from last 20–25 segments.

Parapodia reduced, anterior parapodial shoulders not evident. Setae all capillaries for about first 60 setigers, with notosetae longer than neurosetae; long natatory-like setae not present. Transition to acicular spines occurs at about setiger 60 or in posterior one-third of body. With appearance of spines, parapodia becoming higher, forming elevated membranes in last ten segments with a dorsal gap between notopodia. These membranes bear complete cinctures of spines, with up to 12 in notopodia and 10 in neuropodia or up to 22 spines on a side. Spines accompanied by thin alternating capillaries. Individual notoacicular spines narrow, long, slightly curved along shaft and sharply curved apically to narrow, pointed tip that curves back and adheres to shaft. Neuroacicular spines similar, but shorter, thicker at base and with a similar sharply bent tip that curves over toward shaft.

Pygidium with a short, triangular lobe ventral to anus.

Remarks. Chaetozone curvata was the first species in the genus to be described having acicular spines with a sharp tip that curves over and adheres to the shaft. With the description of C. gesae n. sp., there are now seven such species known (see Remarks for C. gesae n. sp., below).

Distribution. Central and southern Chile, 82– 260 m.