Bathycopola dicarpae, 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 : 35-38

Bathycopola dicarpae gen. et sp. nov.

( Figs. 18 , 19 )

Type material. Holotype ♀ (MNHN-IU-2018-1947, dissected and mounted on a slide) from aẚcarpa lata Monniot C. & Monniot F., 1976 (MNHN-IT-2008-2786 = MNHN S1 / DIC/10 ); Angola Basin , South Atlantic, Walda cruise, RV “Jean Charcot”, Stn Cy 02 (18°52.1’S, 07°23.1’E), depth 5124 m, 06 June 1971.

Etymology. The generic name of the ascidian host, aẚcarpa, provides the specific name of the new species.

Description of female. Body ( Fig. 18A, B ) narrow; body length 1.88 mm. Prosome cylindrical, unsegmented, 1.24× 0.42 mm, occupying 66% of body length, with parallel lateral margins. Cephalic shield distinct; 4 pedigerous somites obscurely discernible by traces of tergites and surface wrinkles. Urosome ( Fig. 18C ) directed posteroventrally, 5-segmented; first urosomite (fifth pedigerous somite) short, obscure. Genital somite 242×197 μm, bearing small copulatory pore proximally on ventral surface. Three abdominal somites 152×148, 121×136, and 76×115 μm, respectively. Caudal rami widely separated from each other; each ramus ( Fig. 18D ) about 3.04 times longer than wide (76×25 μm), as long as anal somite; armed with 1 lateral seta, 1 subdistal seta, and 3 spines and 1 seta distally; distal spines shorter than ramus width, longest one 15 μm long, and smallest seta spiniform; subdistal seta 40 μm long, about twice as long as lateral seta; lateral seta positioned at 44% region of ramus length.

Rostrum absent. Antennule ( Fig. 18E ) slender, about 220 μm long, 6-segmented with second segment sub- divided into 3 and 5 setae regions; armature formula 2, 8, 4, 6+aesthetasc. 2+aesthetasc, and 9+2 aesthetascs; second to terminal segments ornamented with 1 to 6 transverse rows of fine spinules. Antenna ( Fig. 18F ) 4-segmented, consisting of coxa, basis, and 2-segmented endopod; coxa short and unarmed; basis 1.5 times longer than wide (64×41 μm), broadening distally, armed with 1 large spine distally (45 μm long); first endopodal segment 44×28 μm, about 0.7 times as long as basis, bearing 1 seta on inner margin; second endopodal segment twice as long as wide (36×18 μm), shorter than first; armed with 5 setae (2 in middle and 3 distally) plus terminal claw 32 μm long, slightly shorter than second endopodal segment.

Labrum ( Fig. 18G ) short and broad, bearing 2 pairs of tooth-like processes, as in preceding species, but with shallow posteromedian incision. Mandible ( Fig. 18H ) consisting of coxa and palp; medial margin of coxal gnathobase bearing 1 strong tooth distally and several spinules along middle and proximal regions; palp consisting of basis, exopod and endopod; basis with 3 setae mediodistally; exopod with 4 weakly pinnate setae; endopod incompletely articulated from basis, armed with 5 or 6 setae distally. Maxillule ( Fig. 18I ) consisting of precoxa bearing 9 setae on arthrite and unsegmented palp, bearing coxal endite, basis, and lobate exopod and endopod; armed with 1 seta on coxal endite, 6 on basis along bilobed medial margin (3 on proximal and 3 on distal lobes), 2 large, weakly pinnate setae on exopod, and 3 on endopod. Maxilla ( Fig. 19A ) 4-segmented, consisting of syncoxa, basis, and 2-segmented endopod; syncoxa broad, bearing 2 prominent endites each tipped with 1 seta, seta on proximal endite not articulated at base; basis drawn out to robust claw bearing 2 setae near base; endopod small, with 1 and 4 setae on first and second segments, respectively. Maxilliped ( Fig. 19B ) as spinulose lobe bearing 4 or 5 setae (1 seta positioned at apex).

Legs 1-4 ( Fig. 19 C-F) biramous with 2-segmented rami. Inner coxal seta absent in legs 1 and 2, but present in legs 3 and 4. Rami of legs 1-4 armed with spines only except first exopodal segment of legs 3 and 4 bearing outer seta, outer spine present on same segment in legs 1 and 2. Distal spine on second exopodal segment of legs 2-4 elongated, about 3 times longer than nearby spines. First endopodal segment of legs 1-4 unarmed.Armature formula for legs 1-4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-0; III, I, III	0-0; I, II, I
Leg 2	0-0	1-0	I-0; III, I, III	0-0; I, II, II
Leg 3	0-1	1-0	1-0; III, I, III	0-0; I, II, II
Leg 4	0-1	1-0	1-0; III, I, II	0-0; I, II, II

Leg 5 ( Fig. 19G ) consisting of lamellate protopod and small exopod; protopod 475×330 μm, extending beyond posterior margin of genital somite, bearing 1 thin seta distally; exopod about 1.83 times longer than wide (106×58 μm), slightly tapering; armed with 6 setae (1 on subdistal ventral margin and 5 on distal margin). Leg 6 ( Fig. 19H ) represented by 3 small spiniform elements on genital operculum.

Male. Unknown.

Remarks. Bathycçpçla dẚcarpae gen. et sp. nov. has a 4-segmented maxilla, and is armed with 7 spines on the second exopodal segment of legs 2 and 3, plus 4 spines on the second endopodal segment of leg 4. These features are shared only with the type species, B. karubar gen. et sp. nov. However, B. dẚcarpae gen. et sp. nov. can be readily distinguished from B. karubar gen. et sp. nov. by the following character states: (1) the second endopodal segment of the maxilla bears 4 setae in BK dẚcarpae gen. et sp. nov. (cf. 5 setae in B. karubar gen. et sp. nov.); (2) the maxilliped bears 4 or 5 setae (cf. 7 setae); (3) the second endopodal segment of legs 2 and 3 bears 5 spines (cf. 4 spines); (4) the second exopodal segment of leg 4 bears 6 spines (cf. 7 spines); (5) legs 3 and 4 bear an inner seta on the coxa (cf. seta absent in B. karubar gen. et sp. nov.); and (6) the exopod of leg 5 is about 1.83 times longer than wide (cf. about 2.89 times in B. karubar gen. et sp. nov.).

Figures

FIG. 18. Bathycçpçla dẚcarpae gen. et sp. nov., female. A, habitus, dorsal; B, habitus, right; C, urosome, ventral; D, right caudal ramus, ventral; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars, A, B, 0.2 mm; C, 0.1 mm; D-I, 0.02 mm.

FIG. 19. Bathycçpçla dẚcarpae gen. et sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 3; F, leg 4; G, leg 5; H, genital aperture. Scale bars: A, B, H, 0.02 mm; C-F, 0.05 mm; G, 0.1 mm.