(Figs. 13 A–I; 17 D)
Specimens examined. Holotype: NSMT-Pol. H 561: off Chichijima Island, 27 ° 17.99 'N, 142 °44.00'E – 27 ° 18.08 'N, 142 ° 43.96 'E, 2840–2855 m, 3.2009, St. TE-02(2), R/V Tansei-Maru.
Additional material examined.
Amphicteis vestis Hartman, 1965
Holotype: LACM-AHF POLY 278: North Atlantic, USA, New England continental slope, east of upper end of Block Canyon, 39 ° 58 ' 24 ''N, 70 ° 40 ' 18 ''W, 300 m, Sta. Slope 3: anchor dredge, R/V Atlantis, coll. Sanders, H., Woods Hole Oceanographic Institution, 28 August 1962
Paratype: LACM-AHF POLY 279: from the same station as holotype.
Description. Holotype incomplete and broken between thorax and abdomen, length 7.5 mm, width 0.8 mm. Prostomium roughly pentagonal, with brown pigment spots and short paired nuchal slits, without incision, glandular ridges or eyespots (Fig. 13 A). Border of peristomium and segment I discernable (Fig. 13 A, B). Buccal tentacles smooth. Lower lip smooth. Four pairs of branchiae, all broken off, in a rhomb-like arrangement in segments II–IV (Figs. 13 A, 17 D); branchial groups separated by wide median gap; segmental origin of branchiae indeterminable. Chaetae of segment II (paleae) longer and slightly thicker than following notochaetae (Fig. 13 A, B); paleae tapering evenly to hairlike tips (Fig. 13 C); 10 paleae on each side. Notopodia with capillary notochaetae from segment III, present in 17 chaetigers; notopodia of segments III and IV small, without ventral papilla, dorsally elevated, with fine capillary chaetae (Fig. 13 B); subsequent notopodia larger, with conical ventral cirrus (Fig. 13 D) and narrowly limbate capillary chaetae. Neuropodial tori with uncini from segment VI, present in 14 thoracic uncinigers, conspicuously erect from body, with conical dorsal cirrus (Fig. 13 D). Continuous ventral shields present to thoracic unciniger 8. Intermediate uncinigers absent. Holotype incomplete, with 2 abdominal uncinigers. First abdominal unciniger with dermal fold across dorsum, bearing 4 foliose lobes with median lobes being larger than lateral ones (Fig. 13 E–G). Rudimentary notopodia and glandular pads in abdominal uncinigers absent. Pinnules with dorsal papilla (Fig. 13 F). Pygidium unknown. Thoracic and abdominal uncini with crest of numerous teeth above rostral tooth and basal prow (Fig. 13 H, I).
Remarks. Tanseimaruana boninensis sp. nov. resembles the genotype, T. vestis (Hartman, 1965), in the shape of the prostomium, the arrangement of branchiae, and the presence of 4 foliose lobes in the first abdominal chaetiger. T. boninensis sp. nov. can be distinguished from T. vestis by the presence of ventral papillae in the notopodia, conical dorsal cirri in the tori, and dorsal papillae in the pinnules.
The type specimen broke between thorax and abdomen during a shipment. Drawings were prepared prior to the shipment when the specimen was in one piece (Fig. 13).
Etymology. The species is named after its type locality, the Bonin (Ogasawara) Islands.
Distribution. Off Chichijima Island in the Pacific Ocean, in ca. 2850 m.