Chaetozone cimar, Dean, Harlan K. & Blake, James A., 2007

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 : 44-46

Chaetozone cimar sp. nov.

Figure 2 A–D.

Material examined. Offshore, Pacific coast of Costa Rica. Holotype: Sta. 3, half way between Cano Island and mouth of Terraba river, 0 8° 46'N 83° 45'W., 50 m, sediment, grey color with Oliva shells, 6 Dec 1993, ( MCZ 67144).

A small species, anterior half of body with short segments, oval in cross section with shallow mid-ventral groove, posterior half of body narrower, with segments half as long as wide and somewhat dorsoventrally flattened, podial lobes forming incomplete cinctures; holotype 7.0 mm long, 0.5 mm at widest point for 79 setigers. Parapodia inconspicuous ridges, situated more dorsolaterally in approximately 25-setiger thoracic region. Pygidium with rounded, flat lobe ventral to slightly dorsal anus ( Fig. 2 D). Color in alcohol light tan.

Prostomium long, narrow, pointed, with pair of small, round nuchal organs at posterior margin beneath overlying peristomium; peristomium subequal in length to prostomium, with swollen dorsal crest partially overhanging prostomium; with three subequal asetigerous annulations with swollen dorsal crest extending posteriorly from second annulation and partially overlapping setiger 1, junction between second and third peristomial annulations not visible dorsally ( Fig. 2 A B). Paired dorsal tentacles emerging middorsally above setiger 1 from posterior edge of peristomium, with medial sides touching and forming an angle ( Fig. 2 B). First pair of branchiae on setiger 1, dorsal to notopodial setal fascicle; subsequent branchiae similarly situated, present throughout most of body.

Notopodia low ridges; notosetae consisting of 4–6 medium-length, smooth capillaries in first several setigers; with 6–7 capillaries, including 3–4 short, straight, robust needle-like capillaries accompanied by very elongate capillaries (approximately equal to body width) in anterior and mid-body setigers; notopodial spines from setiger 62, with 2–3 spines at first accompanied by 6–7 smooth capillaries, then grading rapidly to 4–8 spines alternating with equivalent number of long, thin smooth capillaries ( Fig. 2 C); neuropodia low, narrow with 5–6 medium-length capillaries anteriorly; spines from setiger 39, with 2–3 spines at first, accompanied by equal number of medium-length, smooth capillaries, then grading to six spines alternating with equal number of smooth capillaries in subsequent setigers ( Fig. 2 C). Spines slightly bent, robust; notopodial spines somewhat longer than neuropodial spines.

Methyl green staining pattern. Prostomium, peristomium and pygidium not staining, with remainder of body a uniform light blue; anterior region with darkly staining, midventral, longitudinal line.

Habitat. Known only from sandy sediments at 50 m.

Remarks. Chaetozone cimar sp. nov. is most similar to Chaetozone acuta Banse & Hobson, 1968 based on the shape of the prostomium and peristomium, the first occurrence of notopodial and neuropodial acicular spines, and the presence of partial cinctures in the posterior region. The ventral, rounded pygidial lobe is also similar to that of C. acuta . C. cimar sp. nov. differs from C. acuta in that the first branchiae occur on setiger 1 rather than the last peristomial annulation and the bases of the dorsal tentacles are widely separated in C. acuta (fig. 8.2A in Blake 1996) and meet middorsally in C. cimar sp. nov. ( Fig. 2 B). C. cimar sp. nov. also lacks the obliquely shaped, pointed setae and the sheathed acicular spines reported for C. acuta and has smooth, rather than fimbriated, capillaries. C. cimar sp. nov. is also similar to Chaetozone bansei Blake, 1996 in the first occurrence of notopodial and neuropodial spines, the well-developed cinctures of alternating acicular spines and capillaries in the posterior region, and in the shape of the pygidium. However, the dorsal tentacles of C. bansei emerge from a peristomial ridge extending posteriorly to setigers 4–7; the ventralmost neuropodial spines are one-third as long as the dorsalmost notopodial ones (fig. 8.4I in Blake 1996), rather than being subequal to the notopodial spines in C. cimar sp. nov. ( Fig. 2 C), and the capillary setae of C. bansei are fimbriated instead of smooth.

Etymology. The specific name refers to the Centro de Investigación en Ciensias del Mar y Limnologia ( CIMAR ) of the Universidad de Costa Rica, the center of Marine and Limnological research, in honor of its 25th anniversary.

Figures

FIGURE 2. Chaetozone cimar sp. nov. A. Lateral view of anterior end B. Dorsal view of anterior end C. Posterior setiger, anterior view D. Pygidium, dorsal view. Scale bars: A – C = 0.2 mm, D = 20 Μm. a = annulations, no = nuchal organ.