Ascidicola secunda Kim I.H. & Moon, 2011

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 : 9-12

Ascidicola secunda Kim I.H. & Moon, 2011

( Figs. 2 , 3 )

Material examined. 1 ♀ (MNHN-IU-2014-17361, dissected) in mçlycarpa papẚllata (Sluiter, 1886); New Caledonia .

Supplementary description of female. Body ( Fig. 2A ) elongate, cylindrical, clearly segmented; prosomeurosome division indistinct; body length 3.94 mm. Prosome 1.41 mm long, occupying about 36% of body length, consisting of cephalosome and 4 pedigerous somites. Cephalosome 409×600 μm; pedigerous somites becoming gradually longer and wider from first to fourth. Urosome 5-segmented; fifth pedigerous somite and genital somite obscurely defined from each other; both 950×480 μm. Three free abdominal somites 518×400, 455×318, and 349×236 μm, respectively. Spinose pad ornamented with various sizes of spinules present ventrally between last 2 abdominal somites ( Fig. 2B ). Anal somite ( Fig. 2B ) about 1.5 times longer than wide. Caudal ramus ( Fig. 2C ) 2.82 times longer than wide (127×45 μm), 36% as long as anal somite, armed with 1 lateral, 1 subdistal dorsal, and prob- ably 4 distal setae (2 of distal setae missing in Fig. 2A–C ); lateral seta positioned at 43% length of caudal ramus.

Rostrum absent. Antennule ( Fig. 2D ) short, 184 μm long, curved posteriorly, 5-segmented; first segment bear- ing 5 setae; numbers of setae on other segments uncertain due to loss of some setae.Antenna ( Fig. 2E ) 3-segmented, consisting of coxobasis and 2-segmented endopod; coxobasis narrowing distally, armed with 1 spine (52 μm long) distally; short first endopodal segment with 1 spine (45 μm long) subdistally; second endopodal segment elongate, 5.07 times longer than wide (137×27 μm), armed with 1 small spine (15 μm long) near proximal third and 3 setae subdistally, and terminating in small, straight claw (40 μm long).

Labrum ( Fig. 2F ) wider than long, fringed with hyaline covering along lateral margin, and with 2 tooth-like processes at each posterolateral corner. Mandible ( Fig. 2G ) consisting of coxa and palp; coxa with well-developed gnathobase bearing 3 major and 4 minor teeth on medial margin; minor teeth serrate at tip; palp 1-segmented, articulated from pedestal-like extension of coxa, armed with 5 setae (outer proximal seta distinctly larger than other setae). Maxillule ( Fig. 1H ) consisting of precoxa and palp; precoxa bearing 8 naked setae on arthrite; palp not divided, slightly longer than wide, armed with 7 setae (2 longer outer proximal, 3 subdistal, and 2 distal, with inner distal seta spiniform). Maxilla ( Fig. 2I ) 2-segmented; broad first segment (syncoxa) with lobate endite tipped with 2 setae; second segment (allobasis) terminating in spiniform process, armed with 1 spine and 5 setae on outer margin and 1 small seta on inner margin. Maxilliped ( Fig. 2J ) unsegmented, elongate, armed with 4 setae (1 apical and 3 medial), and ornamented with 2 rows of minute spinules.

Legs 1-4 ( Fig. 3 A-D) biramous with 2-segmented rami; coxa and basis broad; inner coxal seta absent; first exopodal segment lacking inner seta; inner setae on endopods large. Distal spine on second exopodal segment of legs 1-4 claw-like, indistinctly articulated from second exopodal segment. First endopodal segment of legs 3 and 4 bearing inner seta, but that of legs 1 and 2 lacking inner seta. Armature formula for legs 1-4 as follows:

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

Leg 5 ( Fig. 2K ) skirt-like, encircling first 2 urosomites, bearing 2 minute vestigial setae on proximal ventral margin ( Fig. 2K ); left and right legs 5 fused proximally on ventral side but separate dorsally. Leg 6 ( Fig. 3E ) represented by 2 large setae and 4 spiniform processes on genital operculum.

Male. Unknown.

Remarks. This species was described from Korean waters (Kim I.H. & Moon, 2011). The caudal ramus of the single female specimen from New Caledonia examined here is distinctly smaller than that of type specimens, only 2.82 times longer than wide (127 ×45 μm) compared to 4.23 times longer than wide (338×80 μm) in the type specimens, and 0.36 times as long as anal somite compared to 0.76 times as long in the type material. This difference in the dimension of the caudal ramus is tentatively interpreted here as intraspecific variation because no other significant difference was observed between the types and the New Caledonian material. Material from both locations exhibits the identical armature of the mouthparts and legs 1-4.

Figures

FIG. 2. Ascẚdẚcçla secunda Kim I.H. & Moon, 2011, female. A, habitus, dorsal; B, distal part of urosome, ventral; C, right caudal ramus, dorsal; D, antennule; E, antenna; F, labrum; G, mandible; H, maxillule; I, maxilla; J, maxilliped; K, leg 5 and genital somite, ventral. Scale bars: A, K, 0.5 mm; B, 0.1 mm; C-I, 0.05 mm; J, 0.02 mm.

FIG. 3. Ascẚdẚcçla secunda Kim I.H. & Moon, 2011,female.A, leg 1; B, leg 2; C, leg 3; D, leg 4; E, leg 6. Scale bars: A-D, 0.05 mm; E, 0.02 mm.

FIG. 1. Ascẚdẚcçla rçsea Thorell, 1859, female. A, mandible; B, maxilla; C, leg 1; D, leg 2; E, leg 3; F, leg 4. Scale bars: 0.05 mm.