Asterocheres scutellatus, 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 : 213

publication ID	https://doi.org/ 10.12651/JSR.2024.13.2.185
persistent identifier	https://treatment.plazi.org/id/ED1887CB-FFE2-FFF7-FF7F-B35FB34565DE
treatment provided by	Felipe
scientific name	Asterocheres scutellatus
status	sp. nov.

Treatment

Asterocheres scutellatus n. sp. ( Figs. 16 View Fig , 17 View Fig )

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 GoogleMaps . 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 View Fig ) 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 View Fig ) 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 View Fig ). 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 View Fig ) as long as wide (18 × 18 μm), armed with 6 setae and ornamented with scales on posteroventral margin.

Rostrum ( Fig. 17A View Fig ) small, short, with blunt distal apex. Antennule ( Fig. 16D View Fig ) 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 View Fig ) 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 View Fig ) 119 μm long, widest at proximal 40% region (38 μm wide at this region); proximal box 47 μm wide. Mandible ( Fig. 16G View Fig ) 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 View Fig ) 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 View Fig ) 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 View Fig ) 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 View Fig ), 2 ( Fig. 17C View Fig ), 3, and 4 ( Fig. 17D View Fig ) 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 View Fig ) consisting of dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment ( Fig. 17F View Fig ) 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 View Fig ) 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.).