Ampharete falcata Eliason, 1955

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 : 82

Ampharete falcata Eliason, 1955

( Figs. 3 A–I; 6C)

Ampharete falcata Eliason, 1955: 3 –6, figure 1 — Holthe 1986a: 35 –37, figure 10, map 9; Hartmann-Schröder 1996: 492 –493.

Specimens examined. Sagami Bay, 35°17.7’N, 139°23.0’E, 60 m, St. W2, 5.1980 (2 cs). Off Tsushima, 34°45.9’N, 129°35.9’E, 64 m, NSMT, St. 25, 8.1968 (11 cs, 10 af; SMF 21643); 34°16.4’N, 130°06.4’E, 95 m, NSMT, St. 36, 8.1968 (1 cs); 34°25.1’N, 129°59.3’E, 115 m, NSMT, St. 35, 8.1968 (7 cs, 17 af); 34°50.6’N, 129°21.3’E, 205 m, NSMT, St. 21, 8.1968 (1 cs); 34°15.1’N, 130°15.0’E – 34°15.0’N, 130°14.9’E, 100 m, Soyomaru, St. SO08-D5, 7.2008 (2 cs). West of Chichijima I., 27°07.31’N, 142°07.70’E – 27°07.03’N, 142°07.64’E, 129– 127 m, Koyo, St. 25, 10.2008 (1 af).

Description. Length 11 to 18 mm, width 1.0 to 1.2 mm. Prostomium with middle lobe delimited by incision, without glandular ridges or eyes ( Fig. 3 A). Buccal tentacles without groove, densely covered with long and slender pinnae ( Fig. 3 B). 4 pairs of smooth to indistinctly annulated, cirriform branchiae in rhomb-like arrangement in the fused segments II + III; branchial groups separated by wide median gap; branchiae of segment II in anterior position, branchiae of segment III in outermost position, branchiae of segment IV in innermost position, branchiae of segment V in posterior position ( Fig. 3 C; 6C). 6–9 short and thick, thorn-like chaetae in fused segments II + III ( Fig. 3 D), usually in equal numbers on both sides, occasionally differing by 1. 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 parapodia absent ( Fig. 3 E). Continuous ventral shields present to thoracic unciniger 10. Elevated or modified notopodia absent. 2 intermediate segments. Body constricted between intermediate and abdominal body region ( Fig. 3 F). 10 abdominal uncinigers. Small glandular pads above pinnules present in intermediate and abdominal uncinigers. Pinnules with small dorsal papilla. Pygidium with terminal anus, surrounded by 1 pair of lateral, long, filiform anal cirri, inserted sub-terminally, 1 pair of ventrolateral, digitiform anal cirri, inserted terminally, and a ring of papillae ( Fig. 3 G). 1 pair of nephridial papillae in segment IV, located posterior to innermost branchiae. Thoracic and abdominal uncini with 9 teeth in 2 alternating rows over basal prow and rostral tooth ( Fig. 3 H, I).

Distribution. North Atlantic from Southwest England and the Kattegat to Spitsbergen. Newly recorded from Japan (southern part of Honshu, Tsushima, Chichijima; 60–205m). All localities are influenced by the warm Kuroshio Current. The species seems to be restricted to water depths less than 400 m.

Figures

FIGURE 3. Ampharete falcata: A: anterior end, dorsal view, 40 x, B: distal part of buccal tentacle, 180 x, C: anterior end of another individual, lateral view, 30 x, D: paleae, 120 x, E: thoracic parapodia, 60 x, F: constriction of abdomen, 22 x, G: posterior end, ventral view, 44 x, H: thoracic uncinus, 1920 x, I: abdominal uncinus, 1800 x.