Chaetozone hystricosa Doner & Blake 2006
Creators: name: Blake, James A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Terebellida
Cirratulidae
Chaetozone
Chaetozone hystricosa

description: Chaetozone hystricosa Doner & Blake, 2006
Figure 36
Chaetozone setosa Blake et al. 1998b: C-1 (in part). Not Malmgren, 1867.
Chaetozone hystricosus Doner & Blake, 2006: 69–71, Fig. 3, 5A, F.
Chaetozone hystricosa: Blake & Levesque 2017: 573.
Material examined. (8 specimens) Northeastern United States, MWRA Harbor & Outfall Monitoring Program: Boston Harbor, Sta. T-05A: Rep. 2, 05 Aug. 2009, 42°20.38’N, 70°57.64’W, 17.5 m (2, MCZ 161948).— Massachusetts Bay, 1997 August Survey, Sta. FF-04, Rep. 1, Aug 1997, 42°17.30′N, 70°25.50′W, 87 m (3, MCZ 1619490); Sta. FF-04: Rep. 2, 14 Aug. 2002, 42°17.30′N, 70°25.50′W, 90 m, 3 specimens on SEM stub (MCZ 161950).
Description. A moderately sized species, adults with 70–80 setigers, 9–15 mm long and up to 0.45 mm wide. Body long, dorsum rounded, venter flattened with mid-ventral groove (Fig. 36A); body segments generally short and crowded anteriorly and less so in posterior cinctured setigers bearing numerous acicular spines. Color in alcohol light tan, lacking any distinctive body pigment.
Pre-setiger region long, narrow, smooth, about as long as first seven setigers (Fig. 36A). Prostomium elongate, pointed anteriorly (Fig. 36A–B); eyespots absent; ciliated oval nuchal organs present on posterior lateral border with peristomium just anterior to oral opening (Fig. 36B, inset). Peristomium smooth, lacking any grooves or annular rings, merging seamlessly with prostomium anteriorly and setiger 1 posteriorly (Fig. 36A–B); dorsal surface with elongate dorsal crest (Fig. 36B); dorsal tentacles arise anterior to setiger 1 with first pair of branchiae lateral and posterior to tentacles (Fig. 36A–B). Second pair of branchiae dorsal to notosetae on setiger 1; subsequent branchiae arise in similar position (Fig. 36A–B).
Anterior parapodia low rounded lobes from which setae emerge; noto- and neurosetae from setiger 1 all capillaries, 7–10 per fascicle in notopodia and 5–7 in neuropodia; capillaries of anterior setigers with fringe of fibrils along one edge (Fig. 36G). Long, thin natatory-like capillaries present along body, not associated with sexual maturity (Fig. 36C–E). Acicular spines from about setiger 40–45 in neuropodia and setiger 45–50 in notopodia. Posterior cinctured segments with deep intersegmental furrows separating highly elevated membranous podial lobes from which spines and capillaries emerge (Fig. 36D–F). In most posterior cinctured setigers, acicular spines 6–7 per fascicle in noto- and neuropodia with 12–14 spines on a side, with narrow dorsal and ventral gaps between fascicles (Fig. 36D–E); spines accompanied by alternating, long, thin capillaries (Fig. 36H); acicular spines curved, thickened, with blunt tips (Fig. 36H).
Pygidium a simple flattened lobe ventral to anal opening (Fig. 36D–E).
Methyl green staining. No pattern.
Remarks. Locally, Chaetozone hystricosa is readily recognized by the long, smooth pre-setiger region where there are no annular rings on the peristomium, which is merged almost seamlessly with both the prostomium and setiger 1. The long, narrow dorsal peristomial crest was not noted in the original description.
Globally, the only species of Chaetozone with a smooth, non-annulated pre-setiger region similar to that found in C. hystricosa, a continental shelf species, are two species from abyssal depths: Chaetozone reticulata Blake, 2018 from the Weddell Sea, Antarctica in 3111 m and Chaetozone truebloodi Blake, 2019 from the equatorial Pacific Ocean in 4880 m. Neither of the two deep-sea species, however, have a dorsal peristomial crest and the prostomium of both species is relatively short and rounded apically instead of being long, narrow, and acutely pointed. In addition, these two species have fewer posterior spines, up to 9 or 11 on a side, instead of 12–14 as in C. hystricosa.
Distribution. Northeastern United States, Boston Harbor to Massachusetts Bay, 15– 90 m.
description: Published as part of Blake, James A., 2022, New species and records of Caulleriella, Chaetocirratulus and Chaetozone (Annelida, Cirratulidae) from continental shelf and slope depths of the Western North Atlantic Ocean, pp. 1-89 in Zootaxa 5113 (1) on page 71, DOI: 10.11646/zootaxa.5113.1.1, http://zenodo.org/record/6340998