Ampharete orientalis ( Annenkova, 1929 )

Imajima, Minoru, Reuscher, Michael G. & Fiege, Dieter, 2012, Ampharetidae (Annelida: Polychaeta) from Japan. Part I: The genus Ampharete Malmgren, 1866, along with a discussion of several taxonomic characters of the family and the introduction of a new identification tool, Zootaxa 3490, pp. 75-88 : 85-87

Ampharete orientalis ( Annenkova, 1929)

( Figs. 5 A–H; 6E)

Asabellides orientalis Annenkova, 1929: 494 –495, plate XXXVIII, figures 50–51, plate XXXIX, figures 60–65.

Specimens examined. Mutsu Bay, 41°01.0’N, 140°52.8’E, 6 m, St. 6, 10.1971 (6 cs, 2 af); 41°07.6’N, 140°50.6’E, 40 m, St. 5, 10.1971 (62 cs, 53 af). Miyako Bay, 39°38.7’N, 142°00.0’E, 38 m, St. 5, 7.1967 (1 cs). Otsuchi Bay, 39°20.7’N, 141°57.5’E – 39°20.6’N, 141°57.6’E, 45 m, St. 5, 10.1978 (14 cs, 3 af; SMF 21645). Onagawa Bay, 38°26.3’N, 141°27.6’E, 15m, NSMT, St. 2, 9.1994 (1 cs, 23 af). Off Emi, Boso Peninsula, 35°01.0’N, 140°04.6’E – 35°01.3’N, 140°05.1’E, 77–83 m, KT-76-16, St. C-2, 9.1976 (1 cs). Sagami Bay, 35°08.6’N, 139°34.9’E – 35°09.0’N, 139°34.8’E, 83 m, St. 4, 9.1979 (1 cs).

Description. Length 5 to 18 mm, width 0.8 to 1 mm. Prostomium with kite-shaped middle lobe delimited by incision, without glandular ridges or eyes ( Fig. 5 A). Buccal tentacles without groove, with 2 ventrolateral rows of long, thick pinnae and 2 ventral rows of very short pinnae. Tips of long pinnae covered by tufts of cilia ( Fig. 5 B). 4 pairs of smooth, cirriform branchiae in 2 transverse lines in fused segments II + III; bases of all 8 branchiae fused to a single stem-like membrane, outermost branchiae of posterior transverse row fused to a slightly lesser degree; branchiae of anterior transverse row separated by small gap, branchiae of posterior transverse row not separated by median gap; branchiae of segment II and segment III in anterior transverse row, exact origin because of fusion not determinable; branchiae of segment IV in innermost position of posterior transverse row, branchiae of segment V in outermost position of posterior transverse row ( Figs. 5 A, C; 6E). Chaetae in fused segments II + III absent. Notopodia with regular capillary notochaetae from segment IV, present in 14 chaetigers. Neuropodial tori with uncini from segment VI, present in 12 thoracic uncinigers. Cirri and papillae in thoracic notopodia absent. Tori with a very small dorsal terminal papilla ( Fig. 5 D). Very well developed continuous ventral shields present to thoracic unciniger 11, weakly developed ventral shields in thoracic unciniger 12. Elevated or modified notopodia absent. 2 intermediate uncinigers. 19 abdominal uncinigers. Well developed glandular pads above pinnules present in intermediate and abdominal uncinigers, occasionally with an offset terminal sphere ( Fig. 5 E, F). Pinnules with small dorsal papilla. Pygidium with terminal anus, surrounded by 1 pair of lateral, cirriform anal cirri, inserted subterminally, and a ring of papillae ( Fig. 5 G). 1 pair of very large digitiform nephridial papillae in segment IV, located posterior to innermost branchiae of posterior transverse row, not separated by median gap. Thoracic uncini with 8 teeth in 2 alternating rows over basal prow and rostral tooth ( Fig. 5 H). Abdominal uncini with 9 teeth in 2 alternating rows over basal prow and rostral tooth.

Remarks. Ampharete orientalis was synonymized with A. sibirica ( Wirén, 1883) by Hartman (1956), along with two other species, Neosabellides alaskensis Treadwell, 1943 and Pseudosabellides littoralis Berkeley & Berkeley, 1943 . However, Hartman (1956) did only examine type material of Treadwell’s species. Hartman blended the descriptions of A. sibirica and A. orientalis together and justified the synonymizations by referring characters described by Annenkova (1929) for A. orientalis to A. sibirica . However, Wirén had not described nor figured the most conspicuous characters of A. orientalis , the unusually fused branchiae and the very large nephridial papillae. Furthermore, the anal cirri of A. sibirica were described as “brevissimi” (= very short), whereas A. orientalis has two long anal cirri and a ring of papillae. Therefore, the synonymy of A. orientalis with A. sibirica is not accepted here.

Distribution. Sea of Okhotsk, Japan (northern part of Honshu, 6–83 m). All localities are influenced by the cold Oyashio Current.

Because of the confusion of Ampharete orientalis with A. sibirica , a species that has been recorded all the way from the Sea of Okhotsk to Alaska, more records of A. orientalis , attributed to A. sibirica , might exist. The records of Neosabellides alaskensis might also potentially represent A. orientalis since the description of Hartman (1956) resembles A. orientalis , rather than A. sibirica .

Figures

FIGURE 5. Ampharete orientalis: A: prostomium and branchiae, dorsal view, 35 x, B: distal end of buccal tentacle, 18 x, C: anterior end, dorsal view, 30 x, D: thoracic parapodium, lateral view, 80 x, E: last thoracic chaetiger and abdominal segments, lateral view, 17 x, F: abdominal parapodium, lateral view, 80 x, G: posterior end, dorsal view, 50 x, H: thoracic uncinus, 835 x.