Ampharete longipaleolata Uschakov, 1950

Jirkov, I. A., 2023, Revision of Ampharete (superspecies finmarchica) (Annelida: Ampharetidae), Invertebrate Zoology 20 (1), pp. 1-26 : 21-24

Ampharete longipaleolata Uschakov, 1950

Figs 24–26 .

Ampharete longipaleolata Uschakov, 1950: 218–219 , fig. 33 (type locality, restricted: pacific coast of the southern Kuril Islands , 414 m 14/9/1949); 1955: 367–368.

MATERIAL. 16 samples (45 specimens): 3 syntypes ZIN 1/15243; DGEH: Hydrobiolog 25, 500 m, 5/6/1984 (2) ; Hydrobiolog 129, 48°15′ N 141°11′ E 650 m, 7/8/1984 (1); Hydrobiolog 193, 46°00′ N 138°20′ E, 700 m, 4/9/1984 (1); Odissey 1.84. 16, 880 m (2); Odissey 33.13, 44°52′ N 149°27,7′ E, 920 m, 25/7/1987 (1); Odissey 34.1A, 42°12.76′ N 130° 59.22′ E 640 m, 7/12/1984 (6); IO RAN: Zhemchug 105, 2083 m (1); Zhemchug 111, 375 m (1); Vitjaz 2.31, 57°45.3′ N 153°45′ E, 440 m, 18/8/1948 (19); Vitjaz 2.34, 58°43′ N 155°56′ E, 296 m, 19/8/1948; Vitjaz 2.59, 57°00′ N 150°53,5′ E, 355 m, 29/8/1948 (2); Vitjaz 12.1739, 52°12′ N 154°28′ E, 359 m, 28/ 9/1952 (1); Vitjaz 12.1745, 53°3′ N 154°30′ E, 299 m, 29/9/1952; Vitjaz 12.1770, 56°30′ N 152°38′ E, 524 m, 4/10/1952 (4); Vitjaz 12.1781, 56°53′ N 152°36′ E, 551 m, 4/10/1952 (6); Vitjaz 39.5640, 44º41′N, 148º57′E, 10/09/ 1966, 780 m (1); Vitjaz 59.7458 42°15′N 131°40′ E, 630–750 m, 27/5/ 1976 (1).

DESCRIPTION. Up to 40 mm in length. The middle lobe of the prostomium blunt-rounded in front, at the base with a whitish glandular field, black eye spots outside the corners of the furrow. Palae unusually well developed. Their bases sharply enlarged, forming cylindrical outgrowths, from which the paleal chaetae come out, forming a complete spiral and even more. Chaetae light yellow, several times thicker and 4 times longer than the most developed notochaeta, extending far beyond the level of the anterior edge of the prostomium, by 2– 5 of its length ( Fig. 24A ). In each group 10–26 of them (in the syntypes 15–20), the number of paleal chaetae increases with the increase in the size of the worm ( Fig. 25 ). The tips of paleal chaetae sharply narrow into a short thread-like tip in worms large 20 mm, in smaller worms tips slowly tapering to filament. Many of the paleal chaetae disheveled at the end, which does not happen in other species of the superspecies. Branchophores form an almost straight line, the second pair of branchiae from the middle is slightly behind the others. Branchostyles smooth, bent back, they reach about C6. At the base of the internal branchophores a pair of small nephridial papillae. 14 TC, 12 TU. 13 AU. Rudimentary notopodia small, no neuropodial cirri. Neuropodia of the thorax, AU1 and AU2 tori, the rest — pinnuli. Pygidium with two long lateral cirri and more or less numerous low papillae. Notochaeta also very large, approximately equal in length to the width of the body narrow bilimbate. Uncini with two rows of teeth, usually 6 in each. Thoracic and abdominal similar. The tube loose, detritus-like, sometimes densely plastered with large grains of sand, the thickness of its walls much smaller than the diameter of the inner hole.

REMARK. In the ZIN collection of 14 specimens, mentioned in the original description, only 3 have been preserved (one without the end of the thorax) from st. 101 R/ V Toporok from a depth of 414 m. The original description also includes a find near Northern Sakhalin at a depth of 65 m, this material in ZIN collection is absent. Judging by the fact that all other known findings I have reviewed, located exclusively on slope, worms from 65 m should belong to a different species. Such species really exist and inhabits shallow depth near Sakhalin. It also have numerous very long paleae, but paleal chaetae slowly tapering to slim tips and it has 12 AU. Therefore, I consider it necessary to limit the type locality only to the area where the preserved syntypes were collected

RANGE ( Fig. 23 ). North-west Pacific, including Sea of Okhotsk and the Japan Sea, slope 375– 2083 m.

Figures

Fig. 24. Ampharete longipaleolata Uschakov, 1950, external morphology. A — dorsal view. np — nephridial papillae, B — thorax-abdomen junction, lateral view of last two thoracic and three first abdominal segments, C — notochaetae, D, E — paleal chaetae, E — disheveled at the end. Scales: A — 2 mm, B — 1 mm, C–E — 0.1 mm. A, B — syntype, C–E — Odissei 1.84,16. Рис. 24. Ampharete longipaleolata Uschakov, 1950, внеШнЯЯ морфологиЯ. A — дорсальный вид. np — нефридиальные папиллы, B — граница торакса и абдомента, вид сбоку двух последних и трёх первых абдоминальных сегментов, C — нотохеты, D, E — Щетинки опахал, E — с раЗлохма- ченной верШиной. МасШтаб: A — 2 мм, B — 1 мм, C–E — 0,1 мм. A, B — синтип, C–E — Одиссей 1.84,16.

Fig. 25. Ampharete longipaleolata Uschakov, 1950, the relationship of the number of paleal chaetae with the size of the worm, Vitjaz 2.31. Рис. 25.Ampharete longipaleolata Uschakov,1950, свЯЗь числа Щетинок опахал с раЗмером червЯ, ВитЯЗь 2.31.

Fig. 26. Ampharete longipaleolata Uschakov, 1950, uncini. A — TU1; B, C — TU12; D — AU2; E — AU3; F — AU11. All scales are equal — 10 µm. Odissei 1.84.16. Рис. 26. Ampharete longipaleolata Uschakov, 1950, неврохеты. A — TU1; B, C — TU12; D — AU2; E — AU3; F — AU11. МасШтаб веЗде один — 10 µm. Одиссей 1.84.16.

Fig. 23. Map showing sampling stations with specimens of Ampharete kudenovi Jirkov, 1994 and A. longipaleolata Uschakov, 1950. Red — A. kudenovi, blue — A. longipaleolata 500 m isobath is shown, triangles — the type localities. Рис. 23.Карта находокAmpharete kudenoviJirkov, 1994 и A. longipaleolata Uschakov, 1950. Красные — A. kudenovi, синие — A. longipaleolata. ПокаЗано 500 м иЗобата, треугольники — типовые местности.