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 zodius n. sp. ( Figs. 40-42 ) https://zoobank.org/urn:lsid:zoobank.org:act:C4B99 292-4679-4171-BE57-91F74DD9CB08 Type material. Holotype (intact ♀ ; HNIBRIV2390), intact paratypes ( 2♀♀ ; HNIBRIV2390), and dissect- ed paratypes ( 1♀ , 1♂ ) from washings of unidentified sponges, Munseom , Seogwipo , Jeju Island ( 33°13 ʹ 35.5 ʺ N , 126°33 ʹ 45.3 ʺ E ), SCUBA diving, depth 25 m , coll. T . W. Jung , H. K. Kim and J. G. Kim , 20 July 2022 . Holotype and intact paratypes have been deposited in the Honam National Institute of Biological Resources ( HNIBR ), Mokpo. Dissected paratypes are retained in the collection of I.-H. Kim . Additional specimens examined. 7♀♀ , 3♂♂ , near Biyangdo , Jeju Island ( 33°24 ʹ 13.2 ʺ N , 126°12 ʹ 12.3 ʺ E ), SCUBA diving, depth 20 m , coll. T . W. Jung , H. K. Kim and J. G. Kim , 15 July 2023 Etymology. The specific name is derived from the Greek zodi (= little animal), alluding to the small body of the new species. Female. Body ( Fig. 40A ) small, slightly depressed dorsoventrally. Body length of dissected and figured specimen 540 μm. Prosome moderately expanded, 340 μm long. Cephalothorax wider than long (218 × 290 μm), distinctly wider than succeeding pedigerous somites. All prosomal somite with rounded lateral corners. Urosome ( Fig. 40B ) 4-segmented. Fifth pedigerous somite 99 μm wide, distinctly wider than genital double-somite, with few spinules on lateral apical region. Genital double-somite as long as wide (80 × 80 μm), subquadrate, with rounded anterolateral corners, angularly produced posterolateral corners, and almost parallel lateral margins; genital apertures positioned dorsally at 40% region of double-somite length. Two free abdominal somites 32 × 54 and 27 × 43 μm, respectively. First free abdominal somite with convex lateral margins. Anal somite with few spinules on posteroventral margin ( Fig. 40D ). Caudal ramus ( Fig. 40C, D ) 1.33 times longer than wide (24 × 18 μm), with convex inner and straight outer margins, distally ornamented with 6 dentiform processes (2 inner ones of them serrate at tip), and armed with 6 short, naked setae (2 dorsal and 4 distal); setae I and V longest but less than twice as long as caudal ramus, oth- er 4 setae shorter than caudal ramus. Rostrum absent. Antennule ( Fig. 40E ) 19-segmented, about 195 μm long; 1st, 9th, penultimate, and terminal segments with 1 seta, 5 setae, 2 setae + aesthetasc, and 11 setae, respectively. Antenna ( Fig. 40F ) with unornamented coxa and basis; exopod 8 × 4 μm, with 3 setae; first endopodal segment 30 μm long, with spinules on outer margin; small second endopodal segment tipped with 1 seta; third endopodal segment with 2 setae; terminal claw spiniform, 42 μm long, 1.4 times longer than first endopodal segment, with spinules along both margins. Fig. 40. Asterocheres zodius n. sp. , female. A, habitus, dorsal; B, urosome, dorsal; C, right caudal ramus, dorsal; D, right caudal ramus, ventral; E, antennule; F, antenna; G, oral siphon; H, mandible; I, maxillule; J, maxilla; K, maxilliped. Scale bars: A, 0.1 mm; B, 0.05 mm; C, D, 0.01 mm; E- K, 0.02 mm. Fig. 41. Asterocheres zodius n. sp. , female. A, leg 1; B, leg 2; C, leg 3; D, leg 4; E, exopod of leg 5; F, right genital aperture. Scale bars: 0.02 mm. Oral siphon ( Fig. 40G ) 114 μm long, rather stout, evenly tapering, reaching insertion of maxilliped, with truncate distal tip. Mandible ( Fig. 40H ) with stylet of 106 μm long; palp 1-segmented, slender, 36 μm long, tipped with 2 weakly pinnate setae (longer seta 69 μm long and short- er one 36 μm long); palp plus longer distal seta 105 μm long, as long as stylet. Maxillule ( Fig. 40I ) bilobed; inner lobe 45 μm long, tipped with 4 setae, longest one of them 60 μm long; outer lobe 19 μm long, tipped with 3 longer (longest one 57 μm long) and 1 short setae. Maxilla ( Fig. 40J ) 2-segmented; proximal segment unornamented; distal segment claw-like, arched, distinctly longer than proximal segment, spinulose along entire length. Maxilliped ( Fig. 40K ) 6-segmented, with armature formula 1, 0, 2, 1, 1, and 1 + claw; terminal segment 21 μm long; claw elongate, spinulose along inner margin, 55 μm long, 2.6 times longer than terminal segment. Fig. 42. Asterocheres zodius n. sp. , male. A, habitus, dorsal; B, urosome, dorsal; C, antennule; D, syncoxa of maxilliped; E, exopod of leg 5. Scale bars: A, 0.1 mm; B, 0.05 mm; C- E, 0.01 mm. Legs 1-4 ( Fig. 41A- D ) with 3-segmented rami; setae on rami, especially those on endopod of leg 4, small. Intercoxal plate of legs 1-3 with few spinules, that of leg 4 smooth. Inner coxal setae present in legs 1 and 2, but absent in legs 3 and 4. Outer seta on basis naked, equal in length in all swimming legs. Basis of leg 1 with spinules on inner distal corner; its inner distal seta proximally broadened, with few setules. Second endopodal segment with unicuspid outer distal corner in leg 1, but with bicuspid corner in legs 2-4. Armature formula for legs 1-4 as follows: Coxa Basis Exopod Endopod Leg 1 0-1 1-1 I-1; I-1; III, 2, 2 0-1; 0-2; 1, 2, 3 Leg 2 0-1 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 2, 3 Leg 3 0-0 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 1 + I, 3 Leg 4 0-0 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 1 + I, 2 Leg 5 ( Fig. 40B ) consisting of 1 naked dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment ( Fig. 41E ) nearly rectangular, 3.27 times longer than wide (49 × 15 μm), unornamented, but armed distally with 3 naked setae; lengths of these setae 31, 37, and 23 μm, respectively, from outer to inner. Leg 6 ( Fig. 41F ) represented by 2 naked setae and 1 small process on genital operculum. Male. Body ( Fig. 42A ) narrower than that of female. Body length 464 μm. Prosome 282 μm long. Cephalothorax longer than wide (193 × 180 μm), with sub-parallel lateral margin. Second pedigerous somite with angular posterolateral corners. Fourth pedigerous somite with nipple-shaped lateral apices. Urosome ( Fig. 42B ) 5-segmented. Fifth pedigerous somite 75 μm wide. Genital somite large, rectangular, wider than long (75 × 105 μm). Three abdominal somites 22 × 59, 18 × 43, and 24 × 39 μm, respectively. First abdominal somite characteristically broadened in posterior region. Caudal ramus 1.18 times longer than wide (20 × 17 μm), armed and ornamented as in female. Rostrum absent. Antennule ( Fig. 42C ) 17-segmented, geniculate between 14th and 15th segments and between 15th and 16th segments; armature formula 1, 2, 2, 2, 2, 1, 2, 2, 7, 2, 2, 4, 2, 2, 2, 1+ aesthetasc, and 10; all setae naked. Antenna as in female. Mouthparts, except maxilliped, as in female. Inner distal seta on first segment (sncoxa) of maxilliped proximally expanded ( Fig. 42D ). Legs 1-4 as in female. Exopodal segment of leg 5 ( Fig. 42E ) 2.83 times longer than wide (34 × 12 μm), with convex outer margin, straight inner margin, armed distally with 3 naked setae. Leg 6 ( Fig. 42B ) represented by 2 small setae on posterolateral corner of genital somite. Remarks. In Asterocheres , the inner coxal seta is often absent in leg 4. However, the absence of the same seta in leg 3 has not been reported in this genus, thus the latter feature of A. zodius n. sp. is unique within the genus, which allows to differentiate the new species from all its congeners. As additional diagnostic features of the new species, the genital double-somite of the female and the genital somite of the male are quadrangular, and the caudal setae are short and naked. These features may clearly characterize the new species.