Siphonostomatoid copepods (Crustacea) mainly associated with marine invertebrates from Korean waters Author Kim, Il-Hoi text Journal of Species Research 2016 2016-10-31 5 3 393 442 http://dx.doi.org/10.12651/jsr.2016.5.3.393 journal article 10.12651/JSR.2016.5.3.393 2713-8615 13146750 Callomyzon macrocephalus n. sp. ( Figs. 27-29 ) Material examined. Seven $$ 6♂♂ from a sponge epibiotic on the scallop Azumapecten farreri (Jones and Preston, 1904) , at Nogok ( 37°12′02″N , 129°20′38″E ) in Samcheok, Gangwon­do, 01 July 2008 . Holotype ($, NIBRIV0000216720 ), allotype ( ♂ , NIBRIV00002167 21), and paratypes (4$$, 4♂♂ , NIBRIV0000216722 ) have been deposited in NIBR , Incheon , Korea . Dissect­ ed paratypes (2$$, 1♂ ) are retained in the collection of the author. Female. Body ( Fig. 27A ) with thick exoskeleton, relatively large prosome and small urosome. Body length 960 μm in dissected largest specimen. Prosome crouched and consisting of cephalothorax and 3 metasomites. Cephalothorax markedly swollen, 513 × 618 μm, much wider than metasomites, with rounded posterolateral corners. Second pedigerous somite (first metasomite) 109 × 425 μm, rectangular. Third and fourth pedigerous somites 342 and 228 μm wide, respectively, mostly con­ cealed by preceding somites in dorsal view. Fourth pedigerous somite with angular posterolateral corners. Urosome ( Fig. 27B ) 4­segmented. Fifth pedigerous somite 127 μm wide. Genital double-somite 125 × 162 μm, with tapering posterolateral corners and with roundly convex anterior part of lateral margins and weakly convex posterior part of lateral margins (140 μm wide across posterior part); genital area located dorsally at anterior third. First abdominal somite 58× 69, with convex lateral margins. Anal somite 54 × 48 μm, distinctly narrower than first abdominal somite. Caudal rami small, close to each other, and directed backwards straightly; each ramus 23 × 18 μm, 1.28 times as long as wide, ornamented with fine spinules along posteroventral margin, and armed with 6 setae; 2 dorsal setae slender but characteristically longer than other setae; inner distal seta (seta VI ) naked and other setae plumose; 2 mid­terminal setae (setae IV and V ) not lengthened. Rostrum absent ( Fig. 27J ). Antennule ( Fig. 27D ) 397 μm long and 21-segmented; first segment with setules on anterior surface; armature formula 1, 2, 2, 2, 2 / 2, 2, 2, 7, 2 / 2, 2, 2, 2, 2 / 2, 2, 2 + aesthetasc, 2, 4, and 7; all of setae naked, larger ones of them multiply annulated. Antenna ( Fig. 27E ) with short, unarmed syncoxa; basis 87 μm long, ornamented with longitudinal row of minute pectens in distal half. Exopod small, 15 × 5 μm, with 2 distal and 1 lateral, small setae. Endopod 3­segmented; first segment 73 μm long, with setules or spinules on margins; small second segment with 1 spiniform seta; third segment with 2 setae and terminal, spiniform claw of 56 μm long. Fig. 27. Callomyzon macrocephalus n. gen. n. sp., female. A, habitus, dorsal; B, urosome, dorsal; C, caudal rami, dorsal; D, antennule; E, antenna; F, oral cone; G, mandible; H, maxillule; I, maxilla; J, rostral area, ventral. Scale bars: A, B, J, 0.1 mm; C, 0.02 mm; D­I, 0.05 mm. Fig. 28. Callomyzon macrocephalus n. gen. n. sp., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 4; E, leg 5 exopod; F, right genital aperture. Scale bars: A­C, 0.05 mm; D­F, 0.02 mm. Fig. 29. Callomyzon macrocephalus n. gen. n. sp., male. A, habitus, dorsal; B, urosome, ventral; C, antennule; D, proximal part of maxilliped; E, leg 5 exopod. Scale bars: A, 0.1 mm; B, 0.05 mm; C­E, 0.02 mm. Oral cone ( Fig. 27F ) evenly tapering, 225 μm long, 87 μm in greatest width near base, terminated by linguiform, setulose lamella, and extending to base of maxilliped. Mandible ( Fig. 27G ) consisting of stylet and palp. Stylet 192 μm long, its distal part needle-like, but denticulated in different viewing angle ( Fig. 27G ). Palp 2­ segmented; first segment 44 μm long; second segment 15 μm long, with 2 distal setae of 156 and 77 μm long, respectively. Maxillule ( Fig. 26H ) bilobed; inner lobe 81 μm long, with 5 setae distally; lengths of these 5 setae 104, 103, 99, 75, and 21 μm, respectively; outer lobe 26 μm long, with 4 setae distally; lengths of 4 setae on out­ er lobe 106, 100, 78, and 23 μm long, respectively. Maxilla ( Fig. 27I ) 2-segmented; syncoxa with flexible gland tube proximally and ornamented with longitudinal row of minute spinules proximally; basis forming weakly curved claw bearing rows of spinules. Maxilliped ( Fig. 28A ) 6­segmented; syncoxa with 1 stiff, needle­like seta at inner distal corner; basis 123 × 34 μm, with 1 minute seta at halfway of inner margin and row of spinules on outer margin; armature formula for 4­segmented endopod 2, 1, 1, and 1 + claw; terminal segment 42 μm long; terminal claw 92 μm long, more than twice as long as terminal segment, with fine spinules on concave margin. Legs 1­4 with 3­segmented rami; armature formula as follows: Coxa Basis Exopod Endopod Leg 1: 0­0 1­1 I­1; I­1; III , 2, 2 0­1; 0­2; 1, 2, 3 Legs 2 & 3:0­0 1­0 I­1; I­1; III , I, 4 0­1; 0­2; 1, 2, 3 Leg 4: 0­0 1­0 I­1; I­1; III , I, 3 0­1; 0­2; 0, 2, 1 Coxa of legs 1­4 without inner seta. Inner distal corner of basis of legs 1­3 spinulose, but that of leg 4 naked. Second endopodal segment of legs 1­4 with bicuspid outer distal corner ( Fig. 28 B-D). Outer spine on first exopodal segment of leg 1 28 μm long. Ventral surface of basis of legs 2­4 with several rows of minute spinules. Leg 5 represented by dorsolateral seta on fifth pedigerous somite and free exopod; exopod ( Fig. 28E ) small, 23× 14 μm, armed with 3 distal setae (62, 36, and 31 μm long from outer to inner ones), shortest innermost one of them being plumose. Leg 6 represented by 2 small setae in genital aperture, longer one of them being plumose ( Fig. 28F ). Male. Body ( Fig. 29A ) smaller and narrower than that of female. Body length 647 μm. Cephalothorax 323 × 302 μm, slightly longer than wide. Three metasomites 235, 185, and 118 μm wide, respectively. Urosome ( Fig. 29B ) 5­segmented. Fifth pedigerous somite 85 μm wide. Genital somite sub­circular, 120 × 172 μm, distinctly wider than long. Three abdominal somites 20 × 48, 18 × 36, and 38 × 35 μm, respectively. Anal somite as long as combined 2 preceding somites. Caudal ramus 18 × 14 μm, 1.29 times as long as wide. Rostrum absent as in female. Antennule ( Fig. 29C ) 270 μm long, 18-segmented, and geniculate between antepenultimate and penultimate segments; armature formula 1, 2, 2, 1, 2 / 2, 2, 2, 8, 2 / 2, 2, 2, 2, 2 / 4, 3 + aesthetasc, and 10; penultimate segment with pointed process at anterodistal corner. Antenna as in female. Oral cone, mandible, maxillule, and maxilla as in female. Maxilliped with 1 blunt process proximally on inner margin ( Fig. 29D ). Legs 1­4 as in female. Leg 5 exopod ( Fig. 29E ) 15 × 12 μm, distally armed with 3 naked, unequal setae, longest one of which being 56 μm long. Leg 6 represented by 2 subequal setae tipped on genital operculum ( Fig. 29B ). Etymology. The specific name macrocephalus is a combination of Greek macro (= large) and cephal (= the head). It alludes to the large cephalothorax of the new species. Remarks. In one of four observed samples of leg 4, the third exopodal segment of leg 4 is armed with 4 spines and 2 inner setae (formula III, I, 2) and the third endopodal segment of the same leg is armed with 4 setae (formula 1, 2, 1). These setations are considered to be variations.