Pseudochitinopoma pavimentata Nishi, 1999

Kupriyanova, Elena K., Ten, Harry A. & Nishi, Ejiroh, 2012, A taxonomic revision of Pseudochitinopoma Zibrowius, 1969 (Annelida, Serpulidae) with description of two new species, Zootaxa 3507, pp. 57-78 : 74-75

Pseudochitinopoma pavimentata Nishi, 1999

( Figs 9 A–D, 10A–J)

Pseudochitinopoma pavimentata Nishi, 1999: 89 –93, fig. 1–3; ten Hove & Kupriyanova 2009: 85 (name only).

Material studied. Japan, Tokyo Bay, off Tateyama, Okinoyama, 34°59'N, 139°39'E, 105–113 m, dredged, R/V “ Tansei-Maru” of University of Tokyo, legit T. Komai ( CBM -ZW-50, holotype, complete specimen; CBM -ZM- 51, paratype, incomplete specimen without a tube on SEM stub; CBM -ZM-51, paratype, complete specimen without tube); Tokyo Bay, off Kanaya, Uchibo, approximately 35°10'N, 139°46'E, 200 m, gill netting by-catch, legit E. Kupriyanova and E. Nishi 19 March 2007 ( SAM E3660, 3 specs, including 1 on SEM stub); Sagaminada, Okinoyama, 34˚54’N, 139˚39’E, 105–113 m, legit T. Komai 21 April 1995, don., det. E. Nishi 1995, redet. H.A. ten Hove 1997 ( ZMA V.Pol. 4018, 2 specs).

South China Sea, Taiwan ( Formosa) Strait, 23˚15’N, 117˚40’E, legit H. Christiansen 26 July 1912, det. H.A. ten Hove 1988 Pseudochitinopoma spec.? ( ZMUC -POL-2155, 1 spec.).

Indonesia, Aru Island, Wokam, River Waskai, near to Sungi Manumbai, approximately 6°N, 134°E, legit H. Merton 16 March 1908, det. H.A. ten Hove 1997 Pseudochitinopoma spec. ( SMF 5751, 1 spec.).

Description. TUBE: up to 16 mm long, 1.6 mm wide, with lumen of about 0.4 mm (max. 0.6 mm). Tube attached to substratum over its entire length, lacking wide flaring peristomes. Anterior part of subtriangular in cross-section, with more or less conspicuous non-denticulate keel ( Fig. 9 B) forming sharp tooth above aperture; made of two layers: inner layer white and tough, outer layer thin, semi-transparent, and fragile, usually with shallow pits on upper lateral tube parts (see Nishi 1999, fig. 9B). Middle to posterior part of tube without ornamentation and keel made of a single white solid layer. In specimen from Taiwan Strait, tube surface shiny with glassy hyaline layer.

BRANCHIAE: each lobe short, with up to 10 radioles arranged in semicircles to pectinately, not connected by interradiolar membrane. Pinnules ending with filamentous tips. Branchial eyes not observed.

PEDUNCLE: smooth, circular in cross-section, inserted just below left branchial lobe, covered by thick transparent cuticle. Faint constriction just below operculum.

OPERCULUM: elongated ampulla with more or less conical distal cap covered with a thicker, brown colored cuticle and having sub-dermal (not showing under SEM) layer of whitish granules or flakes arranged like stones in cobblestone pavement ( Fig. 9 A, C–D). Opercular ampulla with a central cavity visible through the wall. Length of the operculum up to 1 mm, width up to 0.5 mm.

COLLAR AND THORACIC MEMBRANES: collar low, divided into large median lobe and pair of laterodorsal ones of equal length, continuing to chaetiger 3.

THORAX: with collar chaetiger and six uncinigerous chaetigers ( Fig. 9 A). Collar chaetae of two types: special fin-and-blade chaetae with proximal denticulate fin not separated from distal limbate blade (Fig. 10E–F) and fine limbate, almost capillary. Subsequent chaetae limbate, of two sizes. Apomatus -chaetae absent. Uncini along entire thorax saw-shaped, with 10–11 curved teeth with gouged flat peg (dental formula P:1:1:1:1:1:1:1:1:1, Fig. 10A, G, H). Number of uncini in a torus increasing posteriorly.

ABDOMEN: up to 40 abdominal chaetigers. Chaetae true trumpet-shaped with about 10 pairs of teeth arranged in two rows (Fig. 10B–C, I–J). Capillary chaetae present in posterior chaetigers. Pygidium bilobed. Anterior uncini saw-shaped or saw-to-rasp shaped (dental formulae P:1:1:1:1:1:1:1:1:1, P:2:1:1:1:1:1:1:1:1, Fig. 10D), posterior rasp-shaped, with 3–4 rows of teeth and 9–10 teeth in profile view.

SIZE: length up to 12 mm (holotype), generally 6–12 mm. Branchiae and operculum about 2 mm long.

COLOUR: preserved specimen semi-transparent white, alive red.

Distribution. North-Western Pacific Ocean: Central Japan; Formosa Strait, South China Sea; Indonesia.

Reproduction. Unknown.

Remarks. Nishi (1999) distinguished P. pavimentata from P. occidentalis , the only Pseudochitinopoma species known at that time, by the characteristic cobblestone pavement-like ornamentation of the operculum.

FIGURE 10. Pseudochitinopoma pavimentata , SAM E3660, SEM, A—uncini of 2nd thoracic segment, B—abdominal chaeta, C—close-up view of the hollow part of the abdominal chaeta, D—anterior abdominal uncini; paratype CBM -ZW-51: E, F—collar chaetae, G, H—anterior abdominal uncini, I—abdominal chaeta, J—close-up view of the hollow part of the abdominal chaeta.

Scale: A, B—10 µm, C—1 µm, D, F—10 µm, G—5 µm, H—10 µm, I—10 µm, J—2 µm.

Figures

FIGURE 9. Pseudochitinopoma pavimentata, CBM - ZW- 50, A—lateral view of the holotype, B—anterior part of the holotype tube, C—radiolar crown and operculum of the holotype, CBM - ZW- 52, D—operculum of the paratype. Scale: A, B— 1 mm, C, D— 0.5 mm.