Asterocheres zodius, 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 : 247-251

publication ID	https://doi.org/ 10.12651/JSR.2024.13.2.185
persistent identifier	https://treatment.plazi.org/id/ED1887CB-FFC0-FFA9-FC96-B39CB1EE6713
treatment provided by	Felipe
scientific name	Asterocheres zodius
status	sp. nov.

Treatment

Asterocheres zodius n. sp. ( Figs. 40-42 View Fig View Fig View Fig )

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 GoogleMaps . 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 GoogleMaps

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 View Fig ) 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 View Fig ) 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 View Fig ). Caudal ramus ( Fig. 40C, D View Fig ) 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 View Fig ) 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 View Fig ) 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.

Oral siphon ( Fig. 40G View Fig ) 114 μm long, rather stout, evenly tapering, reaching insertion of maxilliped, with truncate distal tip. Mandible ( Fig. 40H View Fig ) 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 View Fig ) 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 View Fig ) 2-segmented; proximal segment unornamented; distal segment claw-like, arched, distinctly longer than proximal segment, spinulose along entire length. Maxilliped ( Fig. 40K View Fig ) 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.

Legs 1-4 ( Fig. 41A- D View Fig ) 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 View Fig ) consisting of 1 naked dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment ( Fig. 41E View Fig ) 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 View Fig ) represented by 2 naked setae and 1 small process on genital operculum.

Male. Body ( Fig. 42A View Fig ) 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 View Fig ) 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 View Fig ) 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 View Fig ).

Legs 1-4 as in female. Exopodal segment of leg 5 ( Fig. 42E View Fig ) 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 View Fig ) 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.