Notophyllum imajimai, Kato & Pleijel, 2002

Kato, Tetsuya & Pleijel, Fredrik, 2002, A revision of Notophyllum Örsted, 1843 (Phyllodocidae, Polychaeta), Journal of Natural History 36 (10), pp. 1135-1178 : 1152-1154

Notophyllum imajimai sp. n.

(gures 7–9)

Nipponophyllu m japonicum: Imajima and Hartman, 1964: 67–68 , pl. 14, gures a, b. Not Notophyllum japonicum Marenzeller, 1879 .

? Notophyllum imbricatum: Uschakov, 1972: 170–171 ; Okuda, 1939: 227, gure 4. Not Notophyllum imbricatum Moore, 1906 .

Material examined. Japan: two paratypes (ZIHU-1866), Usujiri , Hokkaido, 17 m, shell and gravel, 29 July 1994 ; two paratypes (ZIHU-1867), Furubira , Hokkaido, 20–60 m, sandy mud, August 1994; holotype and one paratype (ZIHU- 1868, 1869), Oshoro , Hokkaido, intertidal, among barnacles, mussels and kelp holdfasts, 3 September 1994 ; one paratype (ZIHU-1870), Oshoro, June 1995; one paratype ( MNHN-POLY 65 ), Abashiri , Hokkaido, intertidal, 17 April 1998 ; one paratype (ZIHU-1871), Daikoku Island, Akkeshi , Hokkaido, 10 m, 6 July 1995 ; one specimen, Nakaminato, Honshu , 64 m, 10 December 1998 ; one paratype (ZIHU- 1872), Otsuchi Bay, Honshu , 39ss20.7¾N, 141ss57.7¾E, 49 m, sandy mud, 7 May 1997 ; three paratypes (ZIHU-1873), Otsuchi Bay, Honshu , 39ss20.7¾N, 141ss56.2¾E, 15 m, gravel, 7 May 1997 .

Etymology. Named in honour of Dr Minoru Imajima, in recognition of his contributions to polychaetology.

Description. For length and width measurements versus number of segments, see gure 9; holotype largest examined complete specimen, 38.5 mm long and 4.1 mm wide for 86 segments. Body broad, of uniform width, dorso-ventrally attened; dorsum mostly covered by dorsal cirri. Prostomium rounded, about as long as wide, with antero-ventral elongation and a pair of large, rounded eyes with lenses. Length of paired antennae and palps ca two-thirds length of prostomium. Median antenna as long as prostomium or slightly longer, inserted between eyes. Nuchal organs with one to three lobes (gure 7A, B). Juvenile specimens (<5 mm long) with single lobes. Proboscis short, widened distally, wider than prostomium, with lateral rows of rounded papillae on each side; rows absent from proximal part (gure 7B). Lateral papillae in two to four merged rows. Proximal part dorso-laterally with single pair of large and two or three pairs of smaller rounded papillae. Proximal half of proboscis dorsally and ventrally covered with diOEusely distributed minute, rounded papillae, 6–9 m m in diameter (gure 7E); density of minute papillae similar dorsally and ventrally. Distal half covered with larger attened papillae 60–140 m m in maximum diameter (gure 7C). Terminal ring smooth, without papillae. Segment 1 dorsally invisible in both juvenile and adult specimens. Segment 2 dorsally narrow, less prominent than segment 3, occasionally covered by prostomium in larger specimens. Tentacular cirri of segment 1 reaching segment 3–4. Dorsal tentacular cirri of segments 2 and 3 reaching ca segment 11. Ventral tentacular cirri of segment 2 reaching ca segment 4; asymmetrical, posteriorly directed, wider than other tentacular cirri, occasionally with small distinct tips in larger specimens. Segment 2 with ca 10 compound chaetae arising from ventral tentacular cirrophores. Segment 3 with small neuropodial lobes with ca 10 compound chaetae and small ventral cirri. Segments 2 and 3 with dorsal and ventral aciculae (gure 8B, C). Dorsal aciculae absent from segment 4 to 14 (gure 8D, E). Dorsal cirri of median segments broad reniform (gure 8F–I). Tips of dorsal cirri absent both in juvenile and large specimens. Dorsal cirrophores dorsally elongated, from segment 15 with single aciculae and one or two notopodial capillary chaetae. Neuropodia with 15–35 compound chaetae. Ventral cirri reniform. Pygidial cirri attened, oval, slightly longer than wide. Pygidial papilla present.

Colour. Live animals vary from orange, yellow-brown to bluish violet. Preserved specimen whitish or light or dark brown with irregular tint. Eyes blackish.

Habitat. Intertidally among barnacles, mussels and kelp holdfasts, subtidally on bottoms with sand, shell gravel and stones. Intertidally to 64 m depth.

Distribution. Hokkaido and northern Honshu, Japan; records of N. imbricatum by Uschakov (1972) from the Yellow Sea, Sea of Japan, La Pérouse Strait, Aniva Bay, Kuril Islands and Komandorskie Islands may be referred to this species.

Remarks. Notophyllum imajimai diOEers from all other Notophyllum in the combination of dorsally elongated dorsal cirrophores with capillaries, and short and stout proboscis with indistinctly separated lateral rows of rounded papillae. It appears closely related to N. imbricatum , the main diOEerences being the short proboscis and the absence of hook-shaped proboscis papillae. Uschakov’s (1972) records of N. imbricatum are here referred to N. imajimai , because of the absence of hook-shaped papillae. Notophyllum imajimai is also similar to N. foliosum , but diOEers in the short proboscis, in that segment 1 is invisible in dorsal view, in the in ated ventral tentacular cirri in larger specimens and in the absence of distinct dorsal cirral tips in juvenile specimens.

Based on the described presence of notopodial capillary chaetae, and the proboscis lacking rows of discoidal papillae, Imajima and Hartman’s (1964) record of Notophyllum japonicum (as Nipponophyllum japonicum ) from Hokkaido, Japan, is here referred to N. imajimai .