Bathycopola karubar, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, Zootaxa 1, pp. 1-286 : 28-31

Bathycopola karubar gen. et sp. nov.

( 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:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-0; III, I, III	0-0; I, II, I
Legs 2-4	0-0	1-0	I-0; III, I, III	0-0; I, II, I

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.

Figures

FIG. 14. Bathycçpçla karubar gen. et sp. nov., female. A, habitus, dorsal; B, habitus, right; C, genital somite and abdomen, ventral; D, right caudal ramus, ventral; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule; J, maxilliped. Scale bars: A, B, 0.2 mm; C, 0.1 mm; D, G-I, 0.02 mm; E, F, 0.05 mm.

FIG. 15. Bathycçpçla karubar gen. et sp. nov., female. A, maxilla; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5; G, exopod of leg 5. Scale bars: A, 0.02 mm; B-E, G, 0.05 mm; F, 0.1 mm.