Chaetozone ronaldi, Magalhães, Wagner F. & Bailey-Brock, Julie H., 2013

Magalhães, Wagner F. & Bailey-Brock, Julie H., 2013, Bitentaculate Cirratulidae (Annelida: Polychaeta) from the northwestern Pacific Islands with description of nine new species, Zootaxa 3630 (1), pp. 80-116 : 97-98

Chaetozone ronaldi sp. nov.

Figures 12 A–E, 13 A–D

Material examined. Holotype: Mamala Bay, south shore of Oahu Island, Hawaii, Sta. S12R2B, 21°13ʹ38.84ʺ N, 157°56ʹ50.30ʺ W, 481 m, Jan. 1995 (USNM 1195161). Paratypes: same locality and date as holotype, Sta. S5R2B, 21°15ʹ49.15ʺ N, 157°56ʹ18.68ʺ W, 408 m (1 on stub, USNM 1195162; 1, BPBM R3648).

Description. Holotype 2.2 mm long, 0.2 mm wide with 42 chaetigers. Paratypes 2.4–2.5 mm long, 0.2–0.25 wide per 31–44 chaetigers. Body dorsally rounded and ventrally flattened in anterior chaetigers; enlarged dorsal area covering chaetigers 12–15 (end of thorax), forming a “stomach” ( Figs 12 D, 13A); abdominal segments submoniliform to moniliform in far posterior segments, forming complete cinctures ( Figs 12 E, 13C), dorsal groove projects notopodial spines towards mid-dorsum, overlapping notospines ( Figs 12 E, 13C). Pygidium with a simple ventral disk ( Fig. 12 C). Color in alcohol yellow to pale.

Prostomium elongate, conical, tapering anteriorly, nuchal organs or eyes not observed; peristomium with a dorsal crest, well-separated from prostomium, lacking annulation ( Figs 12 A, B, 13A, B). One achaetous segment after peristomium bears a pair of tentacles and a pair of branchiae ( Fig. 13 B). Subsequent branchiae one per chaetiger, dorsal to notochaetae, lacking in very posterior end of the body.

Thoracic region with only capillary chaetae; elongated and natatory-like in the “stomach” region; 8–10 capillaries per notopodia and neuropodia ( Fig. 13 A). Neuroacicular spines from chaetigers 22–24, 3–4 spines alternating with companion capillaries; notoacicular spines from chaetigers 26–27, 3–4 spines alternating with companion capillaries. Complete cinctures present from chaetiger 30–32, with 19–20 acicular spines alternating with same number of companion capillaries; a small dorsal and ventral gap present, notospines projecting toward mid-dorsum, forming a dorsal groove and crossing over, no gap present laterally; spines sharply-pointed with a basal constriction; accompanying capillaries slightly longer than spines ( Figs 12 E, 13C, D).

MGSP. Whole body stains light green, branchiae stain darker. Prostomium intensely stained, leaving anterior tip unstained. “Stomach” region and posterior segments stain a darker green than the rest of the body ( Fig. 12 D). Pygidium stains intensely ( Fig. 12 D).

Remarks. This species is closely related to C. brunnea Blake, 2006 due to the presence of an enlarged “stomach” region in anterior segments, but differs in the paler coloration, presence of complete cinctures with overlapping spines ventrally, and distinct MGSP (see also Table 3).

Etymology. Named after Mr. Ronald Bailey, father of the author JHB-B who introduced her to marine life and later helped collect polychaetes.

Biology/Ecology. Chaetozone ronaldi sp. nov., has been sampled in deep waters (408–481 m) during a study of harbor dredge disposal sites.

Distribution. Mamala Bay, south shore of Oahu Island, Hawaii, USA.

Figures

FIGURE 12. Chaetozone ronaldi sp. nov. A, anterior end, dorsal view; B, anterior end, lateral view; C, posterior end with pygidium; D, MGSP of complete specimen showing strong reaction of the pygidium; E, cross section of a modified chaetiger showing a complete cincture with only a small gap dorsally and spines overlapping ventrally.

FIGURE 13. SEM of Chaetozone ronaldi sp. nov. A, specimen incomplete showing the enlarged “ stomachal ” area and modified abdominal chaetigers; B, anterior end, lateral view; C, thoracic modified chaetigers with complete cinctures and spines overlapping ventrally; D, thoracic spines and companion chaeta.