Sosane uebelackerae sp. nov.

(Figs. 11 A–I; 17B)

Genus A Uebelacker, 1984: 14–16, figs. 9, 10

Specimens examined. Holotype: NSMT-Pol. H 559, Sagami Bay, 35°10.0'N, 139°34.9'E − 35°10.3'N, 139°34.8'E, 84 m, 9.1979. Paratype: NSMT-Pol P 560, 35°08.7'N, 139°34.7'E − 35°08.5'N, 139°34.6'E, 86–89 m, Rinkai-maru, St.1, 4.2002 (1cs). Paratypes: Sagami Bay, SMF 21694, 35°07.5'N, 139°34.6'E − 35°07.9'N, 139°34.4'E, 93−95 m, Rinkai-maru, St. 1, 6.2002 (4cs, 1af); NSMT-Pol. P 569, 35°07.9'N, 139°33.7'E − 35°07.8'N, 139°33.7'E, 100−101 m, Rinkai-maru, St. 1, 1.2003 (1cs); NSMT-Pol. P 570, 35°07.4'N, 139°33.4'E − 35°07.4'N, 139°33.4'E, 177−200 m, Rinkai-maru, St. 2, 1.2003 (1cs). Additional specimens: Sagami Bay, 35°09.1'N, 139°23.3'E − 35°09.1'N, 139°23.9'E, 478−490 m, KT-76-3, St. BS1-1, 2.1976 (3cs). Kushimoto, 33°27.7'N, 135°44.8'E − 33°27.5'N, 135°44.4'E, 44 m, St. 5, 7.1978 (1cs). West of Cape Ashizuri, 32°44.3'N, 132°41.1'E − 32°44.4'N, 132°40.8'E, 124−125 m, KT-99-18, St. DG-8, 12.1999 (1cs).

Additional material examined.

Ampharetidae genus A

3 specimens: USNM 75265. Gulf of Mexico, USA, off Florida, 24°47’11”N, 83°13’08”W, 58 m, modified Reineck box core, Southwest Florida Shelf Ecosystem Study (SOFLA) station 28, November 1980.

1 specimen: USNM 91423. Gulf of Mexico, USA, off Texas, Hospital Rock, 27°32’05”N, 96°28’19”W, 75 m, modified Smith-McIntyre grab, South Texas Outer Continental Shelf Study (STOCS) station HR-1, 1976.

Description. Length 21 mm, width 3 mm. Prostomium with middle lobe delimited by incision, without glandular ridges or eyes (Fig. 11 A). Buccal tentacles unknown. Lower lip crenulated (Fig. 11 A, B). Three pairs of cirriform branchiae in transverse row in segment II (Fig. 11 B, C); branchial groups separated by narrow median gap; branchiae of segment II in 2nd outermost position of transverse row, branchiae of segment III in outermost position of transverse row, branchiae of segment IV in innermost position of transverse row (Fig. 17 B). Innermost and 2nd outermost branchiae distinctly ciliated and annulated, outermost branchiae indistinctly annulated. Chaetae in segment II absent. Notopodia with limbate capillary notochaetae (Fig. 11 D) from segment III, present in 15 segments. Notopodia in second-to-last thoracic unciniger elevated, basally inflated, apically conical, connected by dorsal ridge (Fig. 11 E, F); notochaetae of modified unciniger in fan-like arrangement on convex side of notopodia, with hirsute tips (Fig. 11 G, H). Neuropodial tori with uncini from segment VI, present in 12 thoracic uncinigers. Cirri and papillae in thoracic parapodia absent. Continuous ventral shields present to thoracic unciniger 8. 1 intermediate unciniger. Ten abdominal uncinigers. Rudimentary notopodia and glandular pads in intermediate and abdominal uncinigers absent. Pinnules without cirri or papillae. Pygidium with terminal anus and one pair of ventrolateral cirriform anal cirri. Thoracic and abdominal uncini with arc of 4 small teeth over arc of 3 large teeth above rostral tooth and basal prow (Fig. 11 I).

Remarks. The tips of buccal tentacles are visible in one paratype. Besides the usual, smooth tentacles, some median ones are covered by papillae. Papillated tentacles have never been described in any of the Sosane species. The specimens from Japan do not differ morphologically from the Gulf of Mexico specimens described by Uebelacker (1984) as Genus A, which have since been referred to as Genus A sensu Uebelacker or Sosane sp. Uebelacker.

The three smallest of the four examined specimens from the Gulf of Mexico have ventral tufts of cilia in their branchiae.

This is the first species with the typical Sosane modification in the second-to-last thoracic unciniger. The only other species of the genus with only 3 pairs of branchiae, Sosane bathyalis and S. wahrbergi, have 9 thoracic uncinigers and the modified notopodia in the last thoracic unciniger. All other species with 12 thoracic uncinigers have 4 pairs of branchiae, 2 intermediate uncinigers, and the modified notopodia in the third-to-last thoracic unciniger.

Etymology. The species is named after Joan Uebelacker, who was the first to find this species in the Gulf of Mexico but did not describe it according to the rules of the ICZN.

Distribution. Continental shelf of the northern Gulf of Mexico (Uebelacker 1984). Newly recorded from Sagami Bay and Kushimoto, Pacific coast of Honshu, and to the west off Cape Ashizuri, Pacific coast of southern Shikoku, in 44– 490 m.

The new record from Japan is the first record from the Pacific. The unusual distribution may indicate that Sosane uebelackerae sp. nov. is an introduced species in either the Gulf of Mexico or Japan. Cryptic speciation cannot be excluded.