Enterophilus cercomegalus, Kim, 2000

Kim, Il-Hoi, 2000, Poecilostomatoid Copepods from an Intertidal Mud Flat in the Yellow Sea, Journal of Natural History 34 (3), pp. 367-432 : 390-393

Enterophilus cercomegalus n. sp.

( Figures 13 , 14 )

Material examined. Twenty-six mm and three llin the alimentary canal of the holothurian, Protankyra bidentata (Woodward and Barrett) , collected from the intertidal mud ¯at at Jakyak-do Island o Inchon, on 1 September 1996. Holotype (m), allotype (l) and 17 paratypes (mm) have been deposited in the US National Museum of Natural History , Smithsonian Institution. Other specimens (eight mm, two ll, including two mm and one ldissected) are kept in the collection of the author .

Female. Body (®gure 13A) dorsoventrall y ¯at, 1.05 mm long, Maximum width 430 mm. Prosome consisting of cephalothorax and three pedigerous somites. Cephalothorax, second and third pedigerous somites much wider than long, with well developed, wing-like epimera. Rostral area of cephalothorax roundly produced. Fourth pedigerous somite hexagonal, 170Ö 240 mm, distinctly narrower than preceding somite, without epimerae. Urosome (®gure 13B) ®ve-segmented. Fifth pedigerous somite 182 mm wide, concealed dorsally by fourth pedigerous somite, with round lateral margins. Genital double-somite 78Ö 140 mm, much narrower than ®fth pedigerous somite, with angular lateral protrusions in anterior third; genital area located near this protrusion; a tuft of hairs present near posterior fourth of lateral margin. Three abdominal somites 63 Ö90, 68 Ö100, and 50Ö 120 mm, respectively. Boundaries of these abdominal somites indistinct, but discernible by lateral constrictions. Anal somite deeply notched posteromedially and divergent. Caudal ramus greatly dilated, 175Ö 53 mm (3.30:1), with three minute and one enlarged setae; this enlarged seta naked, longer than caudal ramus, 198Ö 18 mm, with constriction just distal to midlength. Proximal half of outer lateral margin with minute spinules. Outer lateral seta located at midlength of caudal ramus. Other three setae located distally. Egg sac containing only two large eggs, extending to distal border of anal somite.

Rostrum almost absent, represented only by a triangular area of faint sclerotization. Antennule (®gure 13C) six-segmented, tapering distally, with armature formula: 5, 14, 9, 4 +1 aesthetasc, 2 +1 aesthetasc, and 7 +1 aesthetasc. All setae naked and relatively small. Antenna (®gure 13D) four-segmented, with armature formula: 1, 1, 1 +1 claw, and 3 +4 claws. Second segment with many spinules on outer surface. Third segment short; claw very large and strongly curved. Fourth segment about twice as long as wide, with spinules on outer margin; one of four distal claws distinctly longer than other three; distal parts of these four claws spatulate.

Labrum as ®gure 13E, with lobate outgrowth at posterior corner, otherwise unarmed. Mandible (®gure 13F) with one thick, blunt terminal element; this element with spinules. Maxillule ( Fig 13G ) as a lobe distally armed with three glabrous setae. Maxilla (®gure 13H) two-segmented. First segment with a patch of hairs proximally on ventral surface and one spiniform seta distally. Second segment armed terminally with one spine and three setae. Maxilliped (®gure 13I) a weakly sclerotized digitiform process, having scattered spinules.

Leg 1 (®gure 13J), leg 2, leg 3 (®gure 14A), and leg 4 (®gure 14B) with threesegmented exopod and two-segmented endopod. All these legs without inner seta on coxa. Rami of all these legs with many scattered minute spinules on outer side. All spines of exopod of leg 1 and some spines of legs 2±4 with subterminal ¯agellum. All setae on rami of legs 1±4, except for setae on second exopodal segment of legs 1±3, rather sti, spiniform and armed with spinules. Distal endopodal segment of leg 4 terminating in a long process. Armature formula of legs 1± 4 as follows:

Leg 5 (®gure 14C) consisting of one free segment, formed by fusion of original basal and distal segments; nearly elliptical, slightly curved inward, widest in the middle, 142Ö 58 mm (2.45:1), with ®ve setae. One of these ®ve setae located on dorsal surface halfway the length of segment; other four setae located distally, very small; outer margin with two rows of setules in proximal half; setules of proximal row longer than those of distal row; setules of both rows blunt terminally, small aesthetasc-like; inner distal area and ventral surface with minute spinules. Leg 6 not observed.

Male. Body (®gure 14D) resembling that of female. Length 0.99 mm. Urosome (®gure 14E) six-segmented. Genital somite 43Ö 127 mm, about three times as wide as long, narrower than ®fth pedigerous somite and shorter than ®rst abdominal somite. Four abdominal somites 50 Ö115, 59 Ö98, 56 Ö97, and 42Ö 110 mm, respectively. First three abdominal somites with minute spinules on ventral surface. Caudal ramus 153Ö 43 mm (3.49:1); caudal setae as in female.

Antennule, antenna and mouth organs not di erent from those of female, except for maxilliped (®gure 14F) which consists of three segments and terminal claw. First segment unarmed. Second segment greatly expanded inwards, more broadened distally, with slightly concave inner margin and two setae on distal margin. Third segment short and unarmed. Claw rather massive, curved terminally, not extending over inner distal corner of second segment, with minute spinules on inner margin and two extremely unequal proximal setae.

Terminal seta on endopodal distal segment of leg 4 well marked from segment, not fused to segment as in female. No other signi®cant sexual dimorphism seen in legs 1±5. Leg 6 not observed.

Spermatophor e from male (®gure 14G) elongate, 148Ö 40 mm.

Etymology. The speci®c name cercomegalus is from the Greek kerkos (= tail) and megalos (= large). It alludes to the enlarged caudal rami of the new species.

Figures

FIG. 13. Enterophilus cercomegalus n. gen. et n. sp., female: (A) habitus, dorsal; (B) urosome, dorsal; (C) antennule; (D) antenna; (E) labrum; (F) mandible; (G) maxillule; (H) maxilla; (I) maxilliped; (J) leg 1. Scales: A =0.2 mm; B=0.1 mm; C, J = 0.05 mm; D, H = 0.02mm; E, F, G, I = 0.01 mm.

FIG. 14. Enterophilus cercomegalus n. gen. et n. sp. Female: (A) leg 2; (B) leg 3; (C) leg 5. Male: (D) habitus, dorsal; (E) urosome, dorsal; (F) maxilliped; (G) spermatophore. Scales: A±C, G= 0.05 mm; D =0.2 mm; E= 0.1 mm; F= 0.02 mm.