Pectinaria hiuchiensis Kitamori, 1965

Nishi, Eijiroh, Matsuo, Kanako, Kazama-Wakabayashi, Maki, Mori, Atsushi, Tomioka, Shinri, Kajihara, Hiroshi, Hamaguchi, Masami, Kajihara, Naoto & Hutchings, Pat, 2014, Partial revision of Japanese Pectinariidae (Annelida: Polychaeta), including redescriptions of poorly known species, Zootaxa 3895 (3), pp. 433-445 : 439-441

Pectinaria hiuchiensis Kitamori, 1965

[Japanese name: Hiuchi-umi-isagomushi] ( Figs 6–7 )

Pectinaria hiuchiensis Kitamori, 1965 : Kitamori (1965, 47).

Material examined. (Non-type material) CBM-ZW 498, Takamoku-jima, Amakusa, west Kyushu. CBM-ZW 1052, St. AG8D, Ariake Sound, Kyushu, 32.96722222N, 130.42472222E, 12 November 2005, 22 m, mud, dredge, coll. K. Mori. KMNH-IvR 500, 694 and AM W 43556, same data as CBM-ZW 1052.

Description. Based on CBM-ZW 1052 and 498. Body length 38 mm (CBM-ZW 1052) and 45 mm (CBM-ZW 498) including scaphe, width 8.0 mm at cephalic region, 5.0 mm at tail. Crown (operculum) with 9–10 paleae on each side. Paleae stout, flattened golden bristles, tapering to curved pointed tip ( Fig. 6 D). Cephalic membrane (cephalic veil) with 32–35 papillae. Raised cephalic rim without marginal papillae.

First pair of tentacular cirri arise from posterolateral margin of segment I. Second pair of tentacular cirri present on segment II, arise from connecting ridge ( Fig. 6 B). Venter of segments III–V slightly glandular and smooth. Second segment without posterodorsal lobe ( Fig. 6 A, B).

Comb-like branchiae present on segments III–IV, each consisting of series of loose, flat lamellae ( Fig. 6 A, B). Small ear-lobe (lappet) situated on dorsal side of first pair of branchia ( Fig. 6 A). Glandular median plate (ventral shield) on segments III–V; lateral plate of segment IV extending to tuft of branchiae ( Fig. 6 A, B). Dorsal chaetigers 17 pairs (on segments V–XXI), each bearing two kinds of bristles; one bordered with serrations along anterior portion, recurved dorsally, the other chaetae stout, straight, tapering to very acute tip ( Fig. 6 G, H). Uncinigerous tori 13 pairs (on segments VIII–XX), segment XXI with lateral lobe bearing no uncini; uncini with 8 major teeth in lateral view, 6–7 minute (minor) teeth ( Figs 6 J, 7B, C). Scaphe ovoidal, flattened dorsally, broadly divided into 2–3 lobes on each lateral margin by shallow notches, each lobe being furnished with small cirriform papillae ( Fig. 6 A, E). Free end of scaphe with spatulate valve. Scaphal hooks 8–9 pairs, straight and slightly bent towards tip ( Figs 6 F, 7A). Tube made of sand, 40 mm length, tube opening 9.0 mm in width, posterior aperture 5.0 mm wide.

Taxonomic remarks. After the original description by Kitamori (1965), Sato (2010) recorded the species from Kaminoseki, the Seto Inland Sea area of Yamaguchi Prefecture. Sato et al. (2014) also recorded P. hiuchiensis from off Hiroshima, Tokushima, Okayama, and Kagawa, the Seto Inland Sea. The present paper is the fourth record of this species in Japan and a new record from Ariake Sound, extending its distribution westward from the Seto Inland Sea (see Fig. 1).

Among the 22 described species of Pectinaria ( Kitamori 1965, Hutchings & Peart 2002), P. hiuchiensis can be distinguished from other species by a combination of characters: the number of papillae (30–38) on the margin of the cephalic veil, number of pairs of cephalic spines (9–11), number of rows of major teeth on the uncini (2), and the number of pairs of scaphal hooks (9–10). Pectinaria hiuchiensis can be distinguished from other Japanese Pectinaria by the number of major teeth rows on uncinus (2 in P. hiuchiensis , 3–4 in P. okudai ) and the number of chaetigers with uncini (13 in P. hiuchiensis , 12 in P. okudai ). More information on other Pectinaria is in Kitamori (1965: unnumbered Table in p. 48).

The number of cephalic spines, papillae on cephalic veil, and scaphal hooks varies between specimens examined, compared to those described by Kitamori (1965).

Figures

FIGURE 6. Pectinaria hiuchiensis. Body, chaetae, hooks and uncini of CBM-ZW 1052. (A) Entire animal, lateral view. (B) Head and anterior part, lateral view. (C) Head and first chaetiger, dorsal view. (D) Palea. (E) Scaphe, dorsal view. (F) Hooks. (G – H) Chaetae of anterior chaetiger. (J) Uncinus from middle chaetiger. Scale bars 1 mm (A, B, C, E, F); 0.5 mm (D); 50 µm (G); 10 µm (H, J).

FIGURE 7. Pectinaria hiuchiensis. Scanning electron microscope images of hooks and uncini of CBM-ZW 1052. (A) Hooks. (B) Uncini. (C) Posterior small teeth of uncini. Scale bars 20 µm (A); 10 µm (B); 5 µm (C).