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 culicis n. sp. ( Figs. 11-13 ) https://zoobank.org/urn:lsid:zoobank.org:act:C50062C7- 3129-4D86-8636-26E654F08E84 Type material. Holotype (intact ♀ ; MABIK CR0025 4231), intact paratypes ( 6♀♀ , 2♂♂ ; MABIK CR0025 4232), and dissected paratypes ( 1♀ , 1♂ ) from washings of unidentified sponges, Munseom , Seogwipo , Jeju Island ( 33°20 ʹ 17 ʺ N , 126°33 ʹ 48 ʺE ), trimix diving, depth 56 m , coll. T . Lee , 25 April 2023 . Holotype and intact paratypes have been deposited in the Marine Biodiversity Institute of Korea ( MABIK ), Seocheon , Korea . Dissected paratypes are kept in the collection of I.-H. Kim . Etymology. The specific name is derived from the Latin culex (= mosquito), referring to the type locality, meaning “mosquito-laden” in Korean. Female. Body ( Fig. 11A ) moderately broad. Body length 727 μm. Prosome 490 μm long. Cephalothorax 309 × 387 μm, wider than long, distinctly wider than second pedigerous somite. All prosomal somites with rounded or blunt lateral corners. Urosome ( Fig. 11B ) 4-segmented. Fifth pedigerous somite 100 μm wide, as wide as genital double-somite, with row of spinules along posterodorsal margin. Genital double-somite as long as wide (100 × 98 μm), with convex lateral margins bearing 11 postgenital spinules (7 longer anterior and 4 shorter posterior as in Fig. 12G ), and row of spinules (or scales) along posterodorsal margin; genital apertures positioned dorsolaterally at midlength of double-somite. Two free abdominal somite 31 × 54 and 36 × 49 μm, respectively. First free abdominal somite with row of spinules along posterodorsal margin. Anal somite with row of spinules along posteroventral margin ( Fig. 11C ). Caudal ramus ( Fig. 11C ) 1.57 times longer than wide (36 × 23 μm), nearly rectangular, armed with 6 setae and ornamented with spinules along posteroventral margin and at proximal part of inner margin. Rostrum ( Fig. 12A ) strongly tapering, becoming faint distally, lacking distal apex. Antennule ( Fig. 11D ) slen- der, 347 μm long, 21-segmented; 9th, 18th, 20th, and 21st segments with 7 setae, 2 setae + aesthetasc, 4 setae, and 7 setae, respectively; all other segments each with 2 setae; several setae on proximal segments and 1 seta on 20th segments feebly pinnate. Antenna ( Fig. 11E ) with short, unarmed coxa; basis 71 μm long, unarmed but with longitudinal row of spinules near base of exopod; exopod 10 × 5 μm, bearing 3 setae; first endopodal segment 63 μm long, with fine spinules and setules along outer margin; small second endopodal segment with 1 seta distally; third endopodal segment with 3 unequal setae in distal region and terminated in slender claw of 79 μm long. Fig. 11. Asterocheres culicis n. sp. , female. A, habitus, dorsal; B, urosome, dorsal; C, caudal rami, dorsal; D, antennule; E, antenna; F, oral siphon; G, mandible; H, maxillule; I, maxilla; J, maxilliped. Scale bars: A, 0.1 mm; B, F, G, 0.05 mm; C- E, H- J, 0.02 mm. Fig. 12. Asterocheres culicis n. sp. , female. A, rostrum; B, leg 1; C, leg 2; D, endopod of leg 3; E, leg 4; F, leg 5; G, left side of genital double-somite, dorsal. Scale bars: A, 0.05 mm; B- G, 0.02 mm. Fig. 13. Asterocheres culicis n. sp. , male. A, habitus, dorsal; B, urosome, ventral; C, antennule; D, maxilliped; E, endopod of leg 1; F, endopod of leg 2; G, exopod of leg 5. Scale bars: A, 0.1 mm; B- G, 0.02 mm. Oral siphon ( Fig. 11F ) narrow, 255 μm long, 67 μm wide at proximal widest region, extending to intercoxal plate of leg 1. Mandible ( Fig. 11G ) consisting of stylet and palp; stylet 227 μm long, bearing 12 denticles at distal region (arranged as 4, 1, and 7 from proximal to distal); palp 2-segmented, 30 and 12 μm long, respectively, tipped with 2 unequal setae, longer seta 155 μm long, feebly pinnate; smaller seta 68 μm long, naked; palp segments plus longer distal seta 197 μm long, 0.87 times as long as stylet. Maxillule ( Fig. 11H ), small outer lobe 20 μm long, with 4 setae (86, 59, 50, and 27 μm long, respectively); inner lobe 69 μm long, tipped with 4 large and 1 minute setae (4 large setae 145, 139, 136, and 93 μm long, respectively). Maxilla ( Fig. 11I ) slender; proximal segment bearing longitudinal row fine spinules at proximal region; distal segment longer than proximal segment, arched, with fine spinules along concave margin of distal third. Maxilliped ( Fig. 11J ) 6-segmented; armature formula 1, 1, 2, 1, 1, and 1 + claw; second segment (basis) with parallel inner and outer margins, row of fine spinules on distal two-fifths of inner margin, several fine spinules on outer margin; terminal segment and claw 35 and 74 μm long, respectively. Legs 1 ( Fig. 12B ), 2 ( Fig. 12C ), 3, and 4 ( Fig. 12E ) biramous, with 3-segmented rami. Intercoxal plate spinulose in leg 1, setulose in leg 2, and naked in legs 3 and 4. Outer seta of basis large in legs 1-3, but small in leg 4. Inner distal corner of basis spinulose in leg 1, but naked in legs 2-4. Leg 3 similar to leg 2, except bearing 1 spine plus 5 setae on third endopodal segment ( Fig. 12D ). Leg 4 with small inner coxal seta; distal spine on third endopodal segment as long as segment. Armature formula for legs 1-4 as in A. aesthetes : Leg 5 consisting of dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment ( Fig. 12F ) 3.13 times longer than wide (50 × 16 μm), gradually narrowing distally, armed with 3 setae and ornamented with spinules on both inner and outer margins (3 proximal spinules on inner margin longer than other spinules); two distal setae naked, 56 (outer) and 50 μm (middle) long, respectively; inner subdistal seta 28 μm long, feebly pinnate. Leg 6 ( Fig. 12G ) represented by 1 small seta and 1 small spinule on genital operculum. Male. Body ( Fig. 13A ) narrower than that of female. Body length 592 μm. Prosome 412 μm long. Cephalothorax 265 × 301 μm. Urosome ( Fig. 13B ) 5-segmented. Fifth pedigerous somite 79 μm wide. Genital somite 79× 13 μm, with well-developed, distally acutely point- ed genital opercula and spinules on lateral margins. Three abdominal somites 15 × 47, 14 × 45, and 24 × 45 μm, respectively. Caudal ramus 1.43 times longer than wide (30 × 21 μm). Rostrum as in female. Antennule ( Fig. 13C ) 18-segmented, with strong geniculation between 16th and 17th segments, and week geniculation between 15th and 16th segments; 9th, 14th, 17th, and last segments armed with 7 setae, 1 seta, 1 seta + aesthetasc, and 10 setae, respectively; all other segment each bearing 2 setae; several setae on proximal segment with bifurcate tip. Antenna as in female. Oral siphon, mandible, maxillule, and maxilla as in female. Maxilliped ( Fig. 13D ) bearing 1 beak-like protuberance on proximal fourth of inner margin, otherwise as in female. Leg 1-4 with same armature formula as in female, but sexual dimorphisms present in legs 1 and 2. Third endopodal segment of leg 1 ( Fig. 13E ) with enlarged, claw-like outer distal process. Third endopodal segment of leg 2 ( Fig. 13F ) with enlarged, claw-like outer and inner distal processes. Exopodal segment of leg 5 ( Fig. 13G ) nearly rectangular, 2.73 times longer than wide (30 × 11 μm), sparsely spinulose on both margins; all 3 setae naked, midterminal one longest. Leg 6 ( Fig. 13B ) represented by 2 naked setae on genital operculum. Remarks. The comparison of A. culicis n. sp. with its congeners on the basis of the characters listed in Table 2 reveals that five species ( A. ellisi Hamond, 1968 ; A. parvus Giesbrecht, 1897 ; A. peniculatus Kim, 2010 ; A. suberitis Giesbrecht, 1897 ; and A. urabensis Kim, 2004 ) show closeness to the new species, with similarity values more than 75%. These five species are distinguished from the new species by their different features, as follows: A. ellisi has a shorter terminal claw of the antenna, which is shorter than the first endopodal segment, a longer oral siphon which extends beyond leg 1, and no sexual dimorphism in the swimming legs ( Bandera & Mercedes, 2009 ). Asterocheres peniculatus has shorter caudal rami which are wider than long, a short terminal claw of the antenna, which is shorter than the first endopodal segment, and a rudimentary outer distal seta on the third endopodal segment of male leg 3. Asterocheres suberitis has a shorter oral siphon which reaches the insertions of the maxilliped, a longer mandibular palp which is longer than the stylet, and a 17-segmented male antennule ( Giesbrecht, 1899 ). Asterocheres urabensis has shorter caudal rami which are 1.20 times longer than wide, about 15 setules on the postgenital lateral margin of the female genital double-somite, as illustrated in the original description, and an elongated exopodal segment of female leg 5, which is 3.65 times longer than wide ( Kim, 2004a ). Asterocheres parvus was very briefly recorded by Giesbrecht (1899) with figures about the body form and urosome of the female. Giesbrecht (1899) recorded the body length of the female as 0.55 mm long and illustrat- ed the body having pointed posterolateral corners of the first three prosomal somites and the genital apertures positioned at the anterior third of the genital double-somite. In contrast, in A. culicis n. sp. the body of the female is larger, 727 μm long in dissected specimen, all the prosomal somites have rounded posterolateral corners, and the genital apertures are positioned at the midway of the genital double-somite.