Zatsepinia jirkovi, Imajima, Minoru, Reuscher, Michael G. & Fiege, Dieter, 2013

Imajima, Minoru, Reuscher, Michael G. & Fiege, Dieter, 2013, Ampharetidae (Annelida: Polychaeta) from Japan. Part II: Genera with elevated and modified notopodia, Zootaxa 3647 (1), pp. 137-166 : 160-161

Zatsepinia jirkovi sp. nov.

( Figs. 14 A–J; 17E)

Specimens examined. Holotype: NSMT-Pol. H 562, off Shirahama, Boso Peninsula, 34°51.5'N, 139°56.0'E, 95 m, KT-76-16, St. C6-1, 9.1976. Paratype: NSMT-Pol. P 563, same locality as holotype (2cs). Paratypes: Off Emi, Boso Peninsula, NSMT-Pol. P 571, 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 (10cs, 16af); SMF 21695, 35°00.1'N, 140°06.9'E, 150 m, KT-76-16, St. C1-1, 9.1976 (2cs, 18af). Additional specimens: Sagami Bay, 35°07.7'N, 139°36.5'E – 35°07.3'N, 139°36.2'E, 46 m, St. 20', 9.1979 (15cs); 35°0 9.3'N, 139°35.8'E – 35°09.7'N, 139°35.7'E, 50 m, St. 8, 9.1979 (3cs); 35°07.76'N, 139°33.96'E– 35°07.34'N, 139°33.86'E, 100–111 m, Rinkai-maru, St. 1, 10.2006 (5cs); 35°09.4'N, 139°23.3'E, 480 m, KT-66-23, St. 10, 10.1966 (1cs); 35°09.2'N, 139°30.4'E – 35°08.9'N, 139°29.5'E, 590 m, KT-66-12, St. 1, 6.1966 (1cs, 1af); 35°08.2'N, 139°28.4'E, 860 m, KT-67-22, St. 1, 10.1967 (3af); 35°04.1'N, 139°31.5'E – 35°04.2'N, 139°32.1'E, 750–870 m, KT-76-3, St. BS4, 3.1976 (2cs, 2af); 35°00.9'N, 139°35.7'E – 35°00.7'N, 139°36.0'E, 990–1060 m, KT- 66-12, St. 7, 7.1966 (1cs, 1af). Off Shimoda, 34°40.9'N, 139°01.1'E – 34°40.5'N, 139°00.9'E, 102–120 m, St. 31, 10.1981 (2cs); 34°41.1'N, 139°00.0'E – 34°40.9'N, 138°59.8'E, 50–59 m, St. 29, 10.1981 (7cs, 1af). Off Northern Kyushu, 34°01.2'N, 130°24.0'E, 60 m, St. 38, 8.1968 (2cs); 34°08.1'N, 130°28.6'E, 75 m, St. 37, 8.1968 (1cs); 34°23.1'N, 129°27.5'E, 85 m, St. 32, 8.1968 (1cs); 33°49.6'N, 129°29.0'E, 100 m, St. 8, 7.1968 (2cs); 34°25.1'N, 129°59.3'E, 115 m, St. 35, 8.1968 (22cs, 28af); 34°03.3'N, 129°04.5'E, 125 m, St. 11, 7.1968 (4cs, 1af). West of Amami-Oshima Island, 28°32.22'N, 127°01.84'E – 28°31.05'N, 127°01.49'E, 576–594 m, R/V Hakuho-Maru, KH- 05-1, St. OT-6, 5.2005 (1cs).

Description. Holotype incomplete, length 10 mm, width 0.4 mm. Prostomium simple, without glandular ridges or eyes ( Fig. 14 A). Buccal tentacles broad, smooth, with deep ventral groove ( Fig. 14 B, C). Segment II dorsally reduced or overgrown by segment III. Three pairs of cirriform branchiae in arc at anterior end of segment III; branchial groups separated by very small median gap ( Figs. 14 D, 17E); segmental origin of branchiae indeterminable. Chaetae in segments II and III absent. Limbate capillary notochaetae from segment IV, present in 12 segments ( Fig. 14 E). Notopodia reduced in segment IV ( Fig. 14 B, D). Notopodia in second-to-last thoracic unciniger elevated, connected by dorsal ridge ( Fig. 14 F); notochaetae of modified segment with broad wings ( Fig. 14 G). Neuropodial tori with uncini from segment VI, present in 10 thoracic uncinigers. Cirri and papillae in thoracic parapodia absent. Continuous ventral shields distinct to thoracic unciniger 8, faint to thoracic unciniger 10. Four intermediate uncinigers. Holotype incomplete, with 8 abdominal uncinigers. Rudimentary notopodia and glandular pads in intermediate and abdominal uncinigers absent. Pinnules without cirri or papillae. Thoracic uncini with 3 teeth in single row over paired teeth, above rostral tooth and basal prow ( Fig. 14 H, I). Abdominal uncini with crest of numerous teeth above rostral tooth and basal prow.

Remarks. The two paratypes are complete. They have 20 and 21 abdominal uncinigers, respectively. The pygidium bears a pair of blunt ventral lobes ( Fig. 14 J).

Zatsepinia jirkovi sp. nov. is only the second species of the genus. It differs from Zatsepinia rittichae by having 3, rather than 2 pairs of branchiae. The new species has 20–21 abdominal uncinigers, Z. rittichae has only 13–15. Furthermore, the pygidium bears two blunt lobes, whereas Z. rittichae has a pygidium that bears a ring of papillae around the anus. The thoracic uncini have 3 teeth in single row over paired teeth, whereas Z. rittichae has thoracic uncini with two median teeth in a single row over 4 teeth in 2 lateral rows.

Despite the differences that require an emendation of the generic diagnosis, we refrained from describing a new genus. The shape of the prostomium, the absence of chaetae in segment III, the type and position of the elevated notopodia connected by a dorsal ridge, and the unusually high number of 4 intermediate uncinigers are unique characters among all ampharetid genera, shared by Z. rittichae and Z. jirkovi sp. nov.

Etymology. The species is named after Igor Jirkov, renowned ampharetid taxonomist, who described the genus Zatsepinia .

Distribution. Off Boso Peninsula, Sagami Bay, and Sagami Sea along the Pacific coast of Honshu, off the northern coast of Kyushu, and off the west coast of Amami-Oshima Island in the East China Sea, in 46–1000 m.

Figures

FIGURE 14. Zatsepinia jirkovi sp. nov. A: prostomium, dorsal view, 67 x, B: anterior end, lateral view, 62 x, C: anterior end, ventral view, 67 x, D: anterior end, dorsal view, 67 x, E: notochaeta, 630 x, F: thoracic uncinigers 8 – 10 and intermediate unciniger 1, lateral view, 50 x, G: modified notochaetae of thoracic unciniger 9, 1023 x, H, I: thoracic uncini, H: 1045 x, I: 1920 x, J: posterior end of a paratype, ventral view, 100 x.