(Figs. 14, 15)

Type material. Holotype ♀ (intact) (MNHN-IU-2018-1945) from Styela squamçsa Herdman, 1881; off Tanimbar Is., Indonesia KARUBAR Expedition Stn CC57 (08°19’S, 131°53’E), depth 603-620 m, Bouchet, Kastoro & Métivier coll., 31 October 1991. 1 ♀ (dissected paratype, MNHN-IU-2014-17362) in S. squamçsa (MNHN-IT-2008- 8357 = MNHN S1 / STY/285), Tanimbar Is., Indonesia, KARUBAR Expedition Stn CP 54 (08°21’S, 131°43’E), depth 836-869 m, Bouchet, Kastoro & Métivier coll., 30 October 1991.

Etymology. The specific name refers to the “KARUBAR” Expedition to Indonesia during which the type specimens were collected.

Description of female. Body (Fig. 14A, B) stout; body length 1.99 mm; maximum width 567 μm across cepha- losome. Prosome cylindrical, consisting of cephalosome and 4 pedigerous somites, with almost parallel margins, distinctly longer than urosome, occupying 65% of total body length. Articulations between pedigerous somites incomplete; tergites weak, sparsely covered with fine setules; tergite of fourth pedigerous somite extended posterodorsally. Urosome 5-segmented, but fifth pedigerous somite obscurely articulated from prosome, directed posteroventrally. Genital somite (Fig. 14C) longer than wide (300×255 μm); gradually narrowing posteriorly, with copulatory pore proximally on ventral surface. Three abdominal somites 182×200, 109×170, and 90×160 μm, respectively; anal operculum distinct, broad. Caudal rami small, extremely widely separated from each other; each ramus (Fig. 14D) 2.68 times longer than wide, slightly curved, narrowing distally; armed with 3 setae (1 lateral, 1 subdistal, and 1 distal), and 3 distal spines; lateral seta positioned at 43% of ramus length; largest of 3 distal spines 24 μm long. Egg sac 745×482 μm, flattened, 2 eggs-thick, containing about 20 eggs; each egg about 160 μm in diameter.

Rostrum represented by blunt anterior prominence of cephalosome. Antennule (Fig. 14 E) slender, 307 μm long, 7-segmented; armature formula 2, 3, 5, 2, 5+aesthetasc, 2+aesthetasc, and 11+2 aesthetascs; setae slender and naked, aesthetascs very small, hardly visible. Antenna (Fig. 14F) 3-segmented, excluding rudimentary coxa; first segment (basis) gradually broadening distally, 1.7 times longer than wide, distally bearing 1 slender spine (63 μm long) ornamented with spinules in distal half; second segment (first endopodal segment) 1.5 times longer than wide, 0.7 times as long as basis, with 1 seta on inner margin; third segment (second endopodal segment) 2.67 times longer than wide (72×27 μm), armed with 2 inner margin setae and 3 distal setae plus slender terminal claw, 0.8 times as long as second endopodal segment.

Labrum (Fig. 14G) much broader than long, strongly tapering, with deep and wide posteromedian incision and medially directed, tooth-like pointed process on each posterolateral apex. Mandible (Fig. 14H) consisting of coxa and palp: medial margin of coxal gnathobase bearing 1 strong distal tooth and several spinule-like denticles along mid-region, and slender, spinulose process proximally; palp biramous, consisting of well-defined basis, exopod, and endopod, armed with 3 setae on basis, 4 setae on exopod, and 6 setae on endopod; all setae naked and distinct. Maxillule (Fig. 14I) consisting of precoxa and palp; precoxa bearing 9 setae on arthrite (5 broad and spiniform); palp trilobate with 2 large setae on outer lobe (representing original exopod), 4 setae on middle lobe (endopod), and 6 setae on medial lobe (basis); 1 seta (original enditic seta of coxa) present between arthrite and medial lobe. Maxilla (Fig. 15A) consisting of syncoxa, basis, and 2-segmented endopod; syncoxa bearing 2 prominent endites, each tipped with 1 seta, distal endite located between syncoxa and basis; basis produced medially, armed with claw plus 2 setae; endopod small, bearing 1 seta on first segment and 5 on second. Maxilliped (Fig. 14J) as unsegmented, digitiform lobe armed with 7 setae (2 apical and 5 on medial margin); ornamented with rows of minute spinules.

Legs 1-4 (Fig. 15 B-E) biramous with 2-segmented rami; coxae lacking inner seta. Exopods and endopods armed only with spines, lacking setae. Outer spine on first exopodal segment large, longer than width of segment. First endopodal segment of legs 1-4 lacking inner seta. Exopods of legs 1-4 bearing same armature formula; endopods of legs 1-4 also bearing same armature formula, as follows:

Leg 5 (Fig. 15F) consisting of lamellate protopod and small exopod: protopod 550×330 μm, nearly elliptical, ex- tending to posterior margin of first abdominal somite, bearing 1 small seta distally; exopod (Fig. 15G) 2.9 times longer than wide (156×54 μm), slightly tapering, armed with 6 setae (1 on ventral margin, 1 subdistally, and 4 dis- tally). Leg 6 not observed.

Male. Unknown.

Remarks. The diagnostic features of Bathycçpçla karubar gen. et sp. nov. are: (1) the antennule is distinctly 7- segmented; (2) the mandibular palp bears a clearly defined exopod and endopod; (3) the maxilla has a 2-segmented endopod armed with 1 and 5 setae on the first and second segments, respectively; (4) all swimming legs lack the inner seta on the coxa; and (5) all endopods of legs 1-4 are armed with four spines on the distal segment.