Chitinopomoides wilsoni Benham, 1927

Ten Hove, Harry A. & Kupriyanova, Elena K., 2009, Taxonomy of Serpulidae (Annelida, Polychaeta): The state of affairs, Zootaxa 2036, pp. 1-126 : 33-36

Chitinopomoides wilsoni Benham, 1927 , Antarctic.

Chitinopomoides wilsoni Benham, 1927: 156–158 , Pl. 5 figs 162–173 [McMurdo Sound, 366 m, British Antarctic “Terra Nova” Exp. Sta. 348, BMNH 1928:2:29:174]; Hartman 1966: 129–130, Pl. 43 figs 4–7 [same, no new data]; Zibrowius, 1969a: 9–10, fig. 3 [re-examined holotype]; Fauchald, 1977: 144 [generic diagnosis]; Uchida, 1978: 74 [name in list].

Material studied. Antarctica, Davis Sea , Wilkes Land , Burton Island , 66°32.94’S, 93°90’E, 80 m, Deep Freeze III, legit R.R. Starr, Sta. 5, Russian St. Mirny, 29.I.1958, det. H.A. ten Hove 1971 (3 thoraxes, 3 abdomens, 1 small spec., tubes, USNM 51505, ZMA V.Pol. 3166) ; Ross Sea , Victoria Land, Robertson Bay area, 77°26’S, 169°30’E, Deep Freeze I, legit Wiston-W. H. Littlewood, R/V “ Edisto ” 1955/56, Sta. 8, 9.II.1956, USNM 51506, det. H.A. ten Hove 1971 (1 broken specimen) ; Argentina, Ushuaia , 54°48’S, 68°19’W, 18 m (10 Faden) legit H. Mag. Samm. 122, don. W. Michaelsen, det. H.A. ten Hove 1982, ZMH P- 17557 (2 spec., tubes, separated from ZMH V 4963, Serpula spec. , det. Augener 1921) .

Description. TUBE: white, up to 1.4 mm wide with lumen of maximally 0.8 mm. Triangular in crosssection when attached, to almost semicircular when free; may bear wide, three-lobed, collar-like peristomes (2 mm across, Fig. 51A), not unlike those figured for Pseudovermilia conchata (ten Hove, 1975 pl. VIIIe, h). Smooth undulating medial keel present. Entire tube-wall (approx. 0.28 mm thick) appearing opaque in stereomicroscopy, though thin (0.03 mm) outer and inner layers are slightly more transparent, milky.

BRANCHIAE: each lobe with 9–10 branchial radioles, arranged short pectinately or almost semi-circular, not connected by branchial membrane. Rachis of radiole rounded triangular in cross-section, extended into flange to which pinnules are attached. Pinnules all more or less equal in size; terminal filament about twice as long as pinnule. Mouth palps not observed. Pair of prostomial eyes not observed. Branchial eyes not observed. Stylodes absent.

PEDUNCLE: smooth, subtriangular in cross section, inserted at left side just between first and second normal radiole, slightly wider than these. The distal part of the peduncle gradually swelling to about 1/2 the width of the opercular ampulla, separated from the latter by a clear constriction. Peduncular wings absent. Pseudoperculum absent.

OPERCULUM: fig-shaped, bilaterally symmetrical, with a distal concave endplate, almost an oblique funnel reaching halfway down into the ampulla ( Fig. 51B–D). Distal plate chitinous, without ornamentation. Length of the operculum about 1.8 mm, width 1.4 mm.

COLLAR and thoracic membranes: collar low, with laciniate edge; continuous with thoracic membranes, ending at chaetiger 2 (1 st row of uncini). Pockets in thoracic membranes absent. Pairs of wart-like protuberances of collar chaetiger absent; tonguelets between ventral and lateral collar lobes absent.

THORAX: with collar chaetiger, and 6 uncinigerous chaetigers. Collar chaetae of two types: fin-andblade and hooded (limbate). Subsequent chaetae hooded, of two sizes. Apomatus chaetae from chaetiger 3 onwards. Uncini along entire thorax saw-shaped, with 12 curved teeth, with blunt, apparently bifurcated peg (dental formula P + 12).

ABDOMEN: abdominal chaetigers up to 62 at least (broken). Anterior uncini rasp-shaped, with peg and 12 teeth when seen in profile; posterior uncini with up to 5 teeth in a row. Chaetae flat geniculate. Short capillary chaetae and glandular pad present in about 12 posterior chaetigers. Pygidium bilobed.

Size: length up to 24 mm. Width of thorax up to 0.8 mm. Branchiae and operculum accounting for 1/5th of entire length.

Colour: no records.

Ecology: no data except for depth, 18–366 m. The USNM material was removed from tubes of Serpula narconensis by H. Zibrowius.

Remarks. All literature records are based on the same specimen, the holotype. Our seven additional specimens are all broken (or juvenile), but none of the thoraxes still have significant parts of the abdomen attached, at most 1 or 2 chaetigers; the numbers of abdominal chaetigers (40, 45, 53, 62) as counted on the loose abdomens thus probably represent almost complete counts. The specimen collected on 9.II.1956 showed eggs in its abdomen.