Callomyzon macrocephalus, Kim, 2016

Kim, Il-Hoi, 2016, Siphonostomatoid copepods (Crustacea) mainly associated with marine invertebrates from Korean waters, Journal of Species Research 5 (3), pp. 393-442 : 433-437

publication ID	https://doi.org/ 10.12651/JSR.2016.5.3.393
persistent identifier	https://treatment.plazi.org/id/96353C58-E74C-FF8F-FC8E-FDD9FC5AFEDF
treatment provided by	Felipe
scientific name	Callomyzon macrocephalus
status	sp. nov.

Treatment

Callomyzon macrocephalus View in CoL n. sp. ( Figs. 27-29 View Fig View Fig View Fig )

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. GoogleMaps

Female. Body ( Fig. 27A View Fig ) 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 View Fig ) 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 View Fig ). Antennule ( Fig. 27D View Fig ) 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 View Fig ) 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.

Oral cone ( Fig. 27F View Fig ) 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 View Fig ) consisting of stylet and palp. Stylet 192 μm long, its distal part needle-like, but denticulated in different viewing angle ( Fig. 27G View Fig ). 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 View Fig ) 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 View Fig ) 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 View Fig ) 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 View Fig 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 View Fig ) 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 View Fig ).

Male. Body ( Fig. 29A View Fig ) 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 View Fig ) 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 View Fig ) 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 View Fig ).

Legs 14 as in female. Leg 5 exopod ( Fig. 29E View Fig ) 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 View Fig ).

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.