Chaetozone hedgpethi Blake, 1996

Dean, Harlan K. & Blake, James A., 2007, Chaetozone and Caulleriella (Polychaeta: Cirratulidae) from the Pacific Coast of Costa Rica, with description of eight new species, Zootaxa 1451, pp. 41-68 : 47-49

Chaetozone hedgpethi Blake, 1996

Figure 4 A–D.

Chaetozone hedgpethi Blake 1996:294 –295, Figures 8.10A–E; Not Dean 2004:139. Chaetozone sp. X: Dean 2004:139.

Material Examined. Costa Rica, Gulf of Nicoya. Sta. 29, 9°54'55"N, 84°45'15"W, 18 m, muddy sand, 11 Jul 1980, (1 USNM 080128); 1 Oct 1980 (1 HKD, as sp. X of Dean 2004). Sta. 34, 9°55'30"N, 84°50'05"W, 24 m, sand, 11 Jul 1980, (1 USNM 080129).

A medium-sized species, body wide and dorsoventrally flattened with narrow mid-ventral groove along body; segments short, much wider than long throughout. All specimens incomplete, lacking posterior end; largest specimen 11.4 mm long, 0.75 mm maximum width in thoracic region, with 144 setigers; other specimens 7.2 mm long by 0.58 mm wide, with 130 setigers ( USNM 080128) and 7.8 mm long, 0.60 mm wide, with 134 setigers ( USNM 080129). Pygidium not present. Color in alcohol light tan.

Prostomium conical, directed dorsally; pair of small, round, dark nuchal organs present ventral to overhanging peristomium ( Fig. 4 A B). Peristomium with swollen dorsal crest; with two asetigerous annulations, first annulation approximately 2× as long as second; second annulation swollen dorsally and extending on to and overlying asetigerous first segment. Dorsal tentacles arising dorsally from second peristomial annulation, first pair of branchiae emerging from asetigerous first segment posterior and medial to dorsal tentacles; subsequent branchiae dorsal to notosetal fascicles.

Parapodia fleshy ridges; thoracic notopodial lobes slightly elevated relative to dorsal surface. Anterior setigers with blade-like capillaries, 6–7 per setal bundle anteriorly, grading to three longer, smooth capillaries with fine fimbriations along one edge; notosetae capillaries throughout (to setiger 144) in largest specimen; with single acicular notopodial spine accompanied by three or four capillaries from setiger 103 and setiger 107 in remaining two specimens ( USNM 0 80128, 080129). Neuropodia with approximately 8–10 capillaries in anterior setigers, gradually being reduced in number posteriorly, capillaries becoming thinner and smoothshafted in mid-body setigers; acicular spines from setiger 61 in longest specimen, and from setigers 74 and 98 in other specimens, first acicular spines single acicular spine accompanied by four capillaries ( Fig. 4 C), grading to 2–3 spines accompanied by 1–2 capillaries in more posterior setigers. Spines robust, narrowed at point of setal emergence ( Fig. 4 D).

Methyl Green staining pattern. Prostomium and dorsum of peristomium staining weakly; dorsal crest of first annulation staining intensely green; parapodia staining with granular stripe across the dorsal and ventral surface of each segment.

Habitat. Chaetozone hedgpethi was collected subtidally in the Golfo de Nicoya at depth of 18–24 meters in sand and muddy-sand sediments. Blake (1996) had previously reported the species from intertidal to shallow subtidal depths in northern California.

Remarks. These incomplete specimens agree with C. hedgpethi in the shape of the prostomium and peristomium. Blake’s (1996) drawings of C. hedgpethi (fig. 8.10B C) show the asetigerous first segment in dorsal and lateral view. The only discrepancy in these figures is lack of recognition of the poorly defined separation between the first and second peristomial annulation. Neuropodial spines first occurred on setigers 70– 115 and notopodial spines on setigers 100–145 in the specimens described by Blake (1996). The neuropodial spines first occur on setiger 61–98 in the present specimens and notopodial spines were present from setigers 103 and 107 in two specimens but were not present in the 144-setiger third specimen. The shape of the neuropodial spines with a constriction at the point of setal emergence as well as the presence of fimbriated capillary setae also agree with C. hedgpethi .

Distribution. This species is now known from intertidal and shallow subtidal habitats from northern California to Costa Rica.

Figures

FIGURE 4. Chaetozone hedgpethi Blake, 1996. A. Lateral view of anterior end B. Dorsal view of anterior end C. Posterior setiger, anterior view D. Acicular spine. Scale bars: A, B = 0.2 mm, C = 0.1 mm, D = 20 Μm. a = annulations, no = nuchal organ, s 1 = segment 1.