Asterocheres dokdoicus, Lee, 2024

Lee, Il-Hoi Kim and Taekjun, 2024, Copepods of the genus Asterocheres Boeck, 1859 (Siphonostomatoida: Asterocheridae) from Korean waters, Journal of Species Research 13 (2), pp. 185-254 : 240-244

publication ID	https://doi.org/ 10.12651/JSR.2024.13.2.185
persistent identifier	https://treatment.plazi.org/id/ED1887CB-FFC9-FFD0-FF41-B7F5B52D60B5
treatment provided by	Felipe
scientific name	Asterocheres dokdoicus
status	sp. nov.

Treatment

Asterocheres dokdoicus n. sp. ( Figs. 35-37 View Fig View Fig View Fig )

https://zoobank.org/urn:lsid:zoobank.org:act:BBA11B01-

AE1C-4E75-B5FC-5409767A48CB

Type material. Holotype (♀, NIBRIV0000909869 ), paratypes (6♀♀, 9♂♂, NIBRIV0000909870 ), and dissected paratypes (1♀, 1♂) from mixed species of sponges, Dokdo Island (37°16 ʹ 46.7 ʺ N, 131°53 ʹ 11.3 ʺ E), depth 45.2 m, trimix diving, coll. T. Lee, 06 July 2022 GoogleMaps . Holotype and intact paratypes have been deposited in the National Institute of Biological Resources ( NIBR), Incheon, Korea. Dissected paratypes are kept in the collection of I.- H. Kim .

Etymology. The new species is named after its type locality, Dokdo Island.

Female. Body ( Fig. 35A View Fig ) moderately broad. Body length of figured and described specimen 822 μm. Mean body length 774 μm (703-870 μm), based on 8 specimens. Prosome 570 × 436 μm. Cephalothorax 353 μm long, wider than long. All prosomal somite bearing rounded lateral corners. Urosome ( Fig. 35B View Fig ) 4-segmented. Fifth pedigerous somite 123 μm wide, bearing spinules (or scales) on dorsolateral surfaces. Genital double-somite slightly wider than long (110 × 114 μm), widest at proximal third, followed by gradually narrowing distal two-thirds; genital apertures positioned dorsolaterally at about 48% region of double-somite length; postgenital lateral margin ornamented with 2 groups of spinules, anterior group containing 10-13 unequally longer spinules, posterior group containing 4 or 5 short- er but thicker spinules ( Fig. 36F View Fig ). Two free abdominal somite 35 × 65 and 38 × 58 μm, respectively. Genital double-somite and first free abdominal somite bearing minute spinules along posterior margin. Posteroventral margin of anal somite smooth, lacking spinules ( Fig. 35C View Fig ). Caudal ramus( Fig. 35C View Fig ) as long as wide (26× 26 μm), ornament- ed with spinules (or scales) on posteroventral, outer, and inner margins.

Rostrum ( Fig. 35D View Fig ) as tapering ridge between antennules, lacking defined posterior apex. Antennule ( Fig. 35E View Fig ) 360 μm long, 21-segmented; 9th, 18th, 20th, and terminal segments with 7 setae, 2 setae + aesthetasc, 4 setae, and 7 setae, respectively; other segments each with 2 setae; some of setae on proximal segments weakly pinnate, truncated, tipped with small setule. Antenna ( Fig. 35F View Fig ) segmented as in other species of genus; coxa short, unarmed; basis with row of needle-like spinules on outer side; exopod 2.44 times longer than wide (11 × 4.5 μm), bearing 1 proximal and 2 unequal distal setae. First endopodal segment 68 μm long, bearing setules or spinules on both margins; second endopodal segment short, with 1 seta; third endopodal segment bearing 2 setae; terminal claw spiniform, weakly arched, 109 μm long.

Oral siphon ( Fig. 35G View Fig ) 212 × 59 μm, extending to intercoxal plate of leg 1. Mandible ( Fig. 35H View Fig ) consisting of coxal stylet and palp; coxal stylet 205 μm long, bearing 12 teeth at distal region; palp indistinctly 2-segmented, 56 (39+ 17) μm long, tipped with 2 pinnate, unequal setae, longer seta 174 μm long, shorter one 86 μm long; palp plus its larger distal seta 230 μm long, 1.12 times longer than stylet. Maxillule ( Fig. 35I View Fig ) bilobed; inner lobe about 73 μm long, bearing 4 distinct and 1 rudimentary setae (4 distinct setae 120, 1,4, 115, and 70 μm, respectively, from inner to outer); outer lobe 29 μm long, bearing 4 setae (lengths of these setae 118, 91, 86, and 28 μm, respectively); precoxal region near base of outer lobe bearing several spinules. Maxilla ( Fig. 35J View Fig ) slender, 2-segmented; proximal segment bearing excretory tube and row of minute spinules at proximal region; distal segment thin, 1.3 times longer than proximal segment, with tuft of setules in middle and rows of spinules along distal third. Maxilliped ( Fig. 35K View Fig ) 6-segmented; armature formula 1, 0, 2, 1, 1, and 1+ claw; terminal segment and claw 39 and 105 μm long, respectively.

Legs 1 ( Fig. 36A View Fig ), 2 ( Fig. 36B View Fig ), 3, and 4 ( Fig. 36D View Fig ) segmented as usual for genus. Leg 3 similar to leg 2, but with 1 spine and 5 setae on the third endopodal segment ( Fig. 36C View Fig ). Intercoxal plate bearing spinules in legs 1-3 but smooth in leg 4. Inner coxal seta present, pinnate in all swimming legs. Inner distal margin of basis in leg 1 spinulose but smooth in legs 2-4. Inner distal seta on basis of leg 1 thin, bipinnate along distal half. Second endopodal segment of legs 1-4 with bicuspid outer distal corner. Armature formula for legs 1-4 as in A. aesthetes .

Leg 5 ( Fig. 35B View Fig ) consisting of dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment ( Fig. 36E View Fig ) 2.47 times longer than wide (47 × 19 μm), armed with 3 setae and ornamented with spinules on outer and inner margins; two distal setae pinnate, 70 (outer) and 65 (inner) μm long, respectively; inner subdistal seta naked, 36 μm long, proximally annulated. Leg 6 ( Fig. 36F View Fig ) represented by 1 pinnate seta and 1 spinule on genital operculum.

Male. Body ( Fig. 37A View Fig ) narrower and smaller than that of female. Body length of dissected specimen 633 μm. Prosome 448 × 333 μm. Cephalothorax 294 μm long. Urosome ( Fig. 37B View Fig ) 5-segmented. Fifth pedigerous somite 91 μm wide. Genital somite 91 × 117 μm, with many spinules on lateral surfaces and group of minute spinules at posterodorsal corners; genital operculum bearing 2 setae on subdistal outer margin, spinules on outer and inner margins, 3-5 setules on inner margin, and acutely pointed distal apex. Three abdominal somites 19 × 59, 14 × 53, and 24 × 50 μm, respectively. Caudal ramus as long as wide (23 × 23 μm).

Rostrum as in female. Antennule ( Fig. 37C View Fig ) 18-segmented; 9th, 13th, and 3 terminal segments armed with 7 setae, 2 setae+ aesthetasc, 3 setae, 4 setae + aesthetasc, and 11 setae, respectively; anterodistal corner of penultimate segment angularly produced. Antenna as in female.

Oral siphon, mandible, maxillule, and maxilla not different from those of female. Maxilliped with beak-like proximal process on inner margin of second segment.

Legs 1 and 4 as in female. Legs 2 and 3 with endopod ( Fig. 37D, E View Fig ) different from those of female; third endopodal segment of leg 2 bearing strong mammiform spine (transformed from a seta) and group of several, needle-like spinules medial to spine; third endopodal segment of leg 3 with expanded distal region bearing curved, claw-like distal process.

Leg 5 exopodal segment ( Fig. 37F View Fig ) 2.50 times longer than wide(35 × 14 μm). Leg 6 ( Fig. 37G View Fig ) represented by 2 setae on genital operculum.

Remarks. Asterocheres dokdoicus n. sp. appears closely related to A. hoi which was described by Bandera & Conradi (2013) on the basis of females collected at Curaçao in the Caribbean Sea. The new species and A. hoi share all character states in 13 characters ( Table 2), thus they cannot be distinguished from each other based on those character states. Differences between the two species are detectable in minor details. According to the original description and illustration of A. hoi , in the female of this Caribbean species, (1) the first segment (syncoxa) of the maxilla is slightly expanded proximally (cf. not expanded in A. dokdoicus n. sp.), (2) the second segment (basis) of the maxilliped bears row of spinules along the inner margin (cf. the margin is smooth in the new species), (3) the inner coxal seta of leg 1 is naked (cf. pinnate in the new species), (4) the outer seta on the basis of legs 1-4 is naked (cf. the outer seta on the basis of leg 1 is also naked but those of legs 2 and 3 are pinnate in the new species), and (5) the exopodal segment of leg 5 is almost three times longer than wide (cf. the segment is 2.47 times longer than wide in the new species).

The male of A. dokdoicus n. sp. has characteristically modified endopods of legs 2 and 3, which are readily observable under the microscope without dissection. Since A. hoi is known only by the female, it is expected that the male of the latter species will be discovered in the future and confirm the distinctiveness of both species.