Copepods of the genus Asterocheres Boeck, 1859 (Siphonostomatoida: Asterocheridae) from Korean waters Author Lee, Il-Hoi Kim and Taekjun text Journal of Species Research 2024 13 2 185 254 journal article 10.12651/JSR.2024.13.2.185 2713-8615 13344859 Asterocheres scutellatus n. sp. ( Figs. 16 , 17 ) https://zoobank.org/urn:lsid:zoobank.org:act:82C6CB C9-E54A-4D00-825B-88EFCDCA4C1B Type material. Holotype (intact ♀ ; MABIK CR002 54237), intact paratypes ( 14♀♀ ; MABIK CR00254238 ), and dissected paratype ( 1♀ ) from washings of unidentified sponges, trimix diving, depth 56 m , Munseom , Seogwipo , Jeju Island ( 33°20 ʹ 17 ʺ N , 126°33 ʹ 48 ʺ E ), coll. T . Lee , 25 April 2023 . Holotype and intact paratypes have been deposited in the Marine Biodiversity Institute of Korea ( MABIK ), Seocheon , Korea . Dissected paratype is kept in the collection of I.-H. Kim Etymology. The name is derived from the Latin scutell (“a little shield”), alluding to the small rostrum of the new species. Female. Body ( Fig. 16A ) small, relatively narrow. Mean body length 488 μm (455-528 μm), based on 10 specimens . Body length of figured and described specimen 526 μm. Prosome 345 μm long, occupying 66% of body length. Cephalothorax 232 × 243 μm; lateral margins of posterior half parallel. All prosomal somites with round- ed lateral corners. Urosome ( Fig. 16B ) 4-segmented. Fifth pedigerous somite as wide as genital double-somite, bearing spinules on dorsolateral surfaces. Genital double-somite 1.12 times longer than wide (86 × 77 μm) widest at anterior 33% region, gradually narrowing along posterior two-thirds; genital apertures positioned dorsolaterally at about 44% region; postgenital lateral margin with 6-9 spinules ( Fig. 17G ). Two free abdominal somites 31 × 41 and 23 × 42 μm, respectively. Anal somite with scales of irregular sizes on posteroventral margin. Caudal ramus ( Fig. 16C ) as long as wide (18 × 18 μm), armed with 6 setae and ornamented with scales on posteroventral margin. Rostrum ( Fig. 17A ) small, short, with blunt distal apex. Antennule ( Fig. 16D ) 210 μm long, 20-segmented; 9th, 18th, and terminal segments with 5 setae, 2 setae + aesthetasc, and 9 setae, respectively; other segments each with 2 setae; setae mostly short. Antenna ( Fig. 16E ) with short, unarmed coxa; basis 55 μm long, unarmed but ornamented with row of fine spinules along distal half; exopod small, 8 × 3.6 μm, bearing 3 setae; first endopodal segment 39 μm long, with longitudinal row of fine spinules on outer margin; small second endopodal segment with 1 seta; third endopodal segment distally with 2 unequal setae; terminal claw 42 μm long. Oral siphon ( Fig. 16F ) 119 μm long, widest at proximal 40% region (38 μm wide at this region); proximal box 47 μm wide. Mandible ( Fig. 16G ) consisting of stylet and palp; stylet 99 μm long, bearing about 6 teeth arranged longitudinally at distal region; palp slender, 36 μm long, tipped with 2 unequal setae, larger seta 89 μm long, feebly pinnate with short setules, shorter seta naked, 30 μm long; palp segment plus longer distal seta 125 μm long, 1.26 times longer than stylet. Maxillule ( Fig. 16H ) bilobed; small outer lobe 17 μm long, bearing 4 naked setae, 2 longer distal setae 45 and 42 μm long, respectively; inner lobe about 45 μm long, tipped with 1 minute and 4 distinct setae, longest one of them 54 μm long. Maxilla ( Fig. 16I ) 2-segmented; proximal segment unarmed and unornamented, bearing excretory tube of maxillary gland; distal segment (basis) slender and much longer than proximal segment, bearing fine spinules and setules on distal half of concave margin. Maxilliped ( Fig. 16J ) 6-segmented; armature formula 1, 1, 2, 1, 1, and 1 + calw; terminal segment 27 μm long; claw 58 μm long, about 2.1 times longer than terminal segment, spinulose along concave margin. Legs 1 ( Fig. 17B ), 2 ( Fig. 17C ), 3, and 4 ( Fig. 17D ) biramous with 3-segmented rami. Distal margin of intercoxal plate with minute spinules in legs 1 and 2, but smooth in legs 3 and 4. Inner distal margin of basis of leg 1 spinulose; inner distal seta broadened at proximal region, with setules on outer margin. Inner seta on coxa small but pinnate in leg 1, well-developed in legs 2 and 3, but rudimentary in leg 4. Armature formula for legs 1-4 as in A. aesthetes . Leg 5 ( Fig. 16B ) consisting of dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment ( Fig. 17F ) 2.0 times longer than wide (30 × 15 μm), with 3 naked setae, these setae 24, 26, and 22 μm long, respectively, from outer to inner; outer and inner margins bearing several spinules. Leg 6 ( Fig. 17G ) represented by 1 small seta and 1 denticle on genital operculum. Male. Unknown. Remarks. Three species of Asterocheres may be comparable with A. scutellatus n. sp. , because they show relatively high similarity values (over 75%) of characters ( Table 2 ) with the new species: A. madeirensis Bandera, Conradi & Lopez-Gonzalez, 2007 ; A. eurychelatus n. sp. ; and A. tetraodontis n. sp. Asterocheres scutellatus n. sp. is differentiated from A. madeirensis by the 21- segmented female antennule (cf. 20-segmented in A. madeirensis ) and by the proximally broadened inner distal seta on the basis of leg 1 (cf. thin in A. madeirensis ); from A. eurychelatus sp. by the long and narrow terminal claw of the antenna (cf. the claw is shorter and broadened in A. eurychelatus n. sp. ) and by the presence of the inner coxal seta on leg 4 (cf. this seta is absent in A. eurychelatus n. sp. ); and from A. tetraodontis n. sp. by the smaller body (mean body length of females 488 μm; cf. 796 μm in A. tetraodontis n. sp. ), by having the six teeth on the mandibular stylet (cf. four teeth in A. tetraodontis n. sp. ), and by the broad inner distal seta on the basis of leg 1 (cf. the seta is thin in A. tetraodontis n. sp. ).