Ampharete kudenovi Jirkov, 1994

Figs 20–23.

Ampharete kudenovi Jirkov, 1994: 28–30, fig. 1.

MATERIAL:13samples (107 specimens): types: 98 specimens Odissey 33.21, 48°16′N 154°44′E, 140–150 m, 3/8/1984 (holotype and 66 paratypes), Odissey 33.22, 50°40′N 154°33′E, 1000 m, 6/8/ 1984 (1); Odissey 34.12, 46°58′N 152°17 E, 450– 480 m, 30/12/1984 (29); Vitjaz 3569, 39°44′ N 142°18′ E, 423 m (1); Odissey 34.1, 1320 m, 10/12/ 1984 (2); Odissey 1, 1320 m (1); Odissey 16, 880 m 26/7/1987 (1); Korolev 37.20, 58°35.56′ N 170°28.1′ W, 630 m, 20/7/1984 (1). Deposed at DGEH. Vitjaz 2 135 48°56′ N 145°25′E, 140 m, 24/9/1948 (1); Vitjaz 10.1576, 60°30′N 168°46′E, 227 m, 25/6/ 1952 (1); Vitjaz 12.1739, 52°12′N 154°28′E, 359 m, 28/9/1952 (1); Vitjaz 12.1857, 56°30′N 143°10′E, 234 m, 19/10/1952 (1); Vitjaz 12.1916, 48°36′N 144°52′E, 111 m, 31/10/1952 (1) Deposed at IO RAN.

DESCRIPTION. Up to 26 mm long. The middle lobe of the prostomium obtusely rounded, along its posterior edge a more or less pronounced glandular field. No eye spots on the prostomium. Buccal tentacles pinnate. Paleal chaetae (Fig. 21A–C) much longer and thicker than the most developed notochaeta, directed forward reach the level of the anterior margin of the middle lobe of the prostomium or at least erased beyond its posterior margin. 6–15 light yellow paleal chaetae on each side (70% have 9–11). 4 pairs of branchiae. Groups of branchophores close, the gap between them varies from almost absent to approximately equal to the diameter of the branchophore. The attachment points of the three branchophores in each group form an almost straight row (Fig. 20C). The fourth located at the back between the inner and middle, it is clearly associated with the TC2 notopodia. Branchostyles of the usual structure for the family:smooth, irregularly transversely wrinkled; bent back, they reach TC7–8. At the inner corners of the bases of the inner pair of branchophores there are small nephridial papillae (Fig. 20A, C), the same papillae present behind the TC3–TC5 notopodia (Fig. 20E), in half of the examined specimens they very clearly visible after staining, in the rest, for the most part, not so good condition are noticeable only on TC3. 14 TC, 12 TU. 13 AU (about 5% — 14AU). Rudimentary notopodia small, no neuropodial cirri. Neuropodia of the thorax, AU1 and AU2 tori, the rest — pinnuli (Fig. 20F). The ventral surface up to and including TU9 is transformed into ñontinuous glandular ventral shields extending from notopodia to notopodia. No ventral shield on TU10, in its place a thickening may be present that occupies the entire ventral abdominal surface of the anterior half of the segment. Notochaetae (Fig. 20H), long and short; probably short ones forming ones. Long notochaetae in a light microscope bilimbate (keels in SEM), very unequal (Fig. 21D, E). Uncini (Fig. 22) generally similar: thoracic uncini in profile 5–6 teeth, teeth arranged in two rows in a checkerboard pattern, the size of the teeth gradually increases apically. Abdominal uncini AU1 similar to thoracic ones; caudally, the number of rows of teeth increases and AU13 uncini in 3–4 rows of teeth. Pygidium with two long lateral cirri and more or less numerous low papillae (Fig. 20G). Tube: transparent organic base covered with fragments of bryozoans, shells, sea urchin spines, mica, etc., without the slightest admixture of the usual for family silt or detritus.

REMARK. The species is very similar to A. finmarchica, and the only reason why I described this species is sharp difference in tube structure. The use of tubes structure for identification may seem doubtful, however, reviewed tubes of A. finmarchica from the extensive materials collected from Newfoundland to the Sea of Japan, including samples in which A. finmarchica has been found together with A. kudenovi, showed that the structure were found to be very monomorphic and tubes of A. finmarchica composed of silt-detrital particles, completely absent in tubes of A. kudenovi, usually more or less densely encrusted in the anterior part of the tube, are found as grains of sand. However, tubes are not always preserved. The number of paleal chaetae of A. kudenovi does not differ from that of A. finmarchica (Fig. 9). The paleal chaetae of A. kudenovi are lighter than those of A. finmarchica and relatively shorter, the tips break off extremely rarely. Tips of paleal chaetae of A. kudenovi are pointed a little gradually than of A. finmarchica . Also, nephridial papillae behind notopodia are extremely seldom visible in A. finmarchica, while often can be seen in A. kudenovi . But these differences cannot be used for identification. I found the only other difference between these species in structure of notochaetae: limbation of A. kudenovi is much wider and shorter than of A. finmarchica (compare Fig. 7k, i and Fig. 16d, e). Unfortunately, this character is not convenient for identification of these common species and even is not visible on each slide. The situation is similar to Oweniidae, some species are very easily differed by their tubes, but if tubes are absent, preparation of slides is necessary.

RANGE (Fig. 23). North-west Pacific, including Sea of Okhotsk and the Bering Sea, lower sublittoral and slope.