Lichomolgus bullatus, 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 : 406-410

Lichomolgus bullatus n. sp.

( Figures 23 ±25)

Material examined. Three mm and four ll from the mantle cavity of a small bivalve, Striarca (Didimacar) tenebrica (Reeve) , collected on the intertidal mud ¯at at Jakyak-do Island o Inchon, on 29 September 1996. Holotype (m), allotype (l), and three paratypes (one m, two ll) have been deposited in the US National Museum of Natural History , Smithsonian Institution. Dissected specimens (one m and one l) are kept in the collection of the author.

Female. Body (®gure 23A) relatively narrow, 1.10 mm long. Greatest width 0.37 mm. Prosome elongate-oval and ®ve-segmented. Urosome (®gure 23B) ®vesegmented, slender and tapering. Fifth pedigerous somite 101 mm wide. Genital double-somite 118Ö 101 mm (1.17:1), with broad anterior expansion and narrower posterior third. Genital area large, located dorsolaterally in posterior part of anterior expansion. Three abdominal somites 30 Ö49, 26 Ö45, and 50 Ö 45 mm, respectively. Anal somite with one row of spinules on each proximal and distal border of ventral surface (®gure 23C). Caudal ramus elongate, 126Ö 16 mm (7.88:1), with six setae; outer lateral seta naked, short, not reaching to end of caudal ramus, and positioned at 60% length of caudal ramus; inner dorsal seta naked, other four setae plumose.

Rostrum tapering, longer than wide, but rounded anteriorly. Antennule (®gure 23D) seven-segmented; armature formula 4, 13, 6, 3, 4 +1 aesthetasc, 2 +1 aesthetasc, and 7 +1 aesthetasc; all setae naked. Antenna (®gure 23E) slender and four-segmented; armature formula 1, 1, 1 +1 claw, and 3 +4 claws. Claw on third segment setiform. One of four terminal claws moderately thick, but other three setiform. Terminal segment about 3.4 times as long as wide.

Labrum not examined. Mandible (®gure 23F) slender, tapering into long lash, with spinulated margins; proximal notch broad and relatively distinct. Maxillule (®gure 23G) a lobe, constricted in the middle, with two terminal setae and one spinule-like subterminal seta. Maxilla (®gure 24A) two-segmented; ®rst segment broad and unarmed; second segment terminating in a long lash bearing spinules on convex side, proximally with one smaller naked seta and one larger seta, the latter spinulated on distal margin. Maxilliped (®gure 24B) three-segmented; ®rst segment unarmed; second segment with two small setae, one of them smaller than the other; terminal segment tapering, terminally curved and pointed, with one small seta.

Leg 1 (®gure 24C), leg 2 (®gure 24D) and leg 3 with three-segmented rami. Leg 4 (®gure 24F) with three-segmented exopod and two-segmented endopod. Outer margin of endopodal second segment of leg 4 with small spiniform process; two terminal spines of this segment unequal. Armature formula of legs 1±4 as follows:

Leg 5 (®gure 24G) consisting of one plumose seta on ®fth pedigerous somite and free segment. Free segment 21Ö 22 mm, characteristically with profound inner inātion, and terminally with one spinule, one naked seta (46 mm) and one spine (27 mm). Leg 6 represented by one plumose and one spiniform seta, and one spinule in genital area (®gure 24H).

Male. Body (®gure 25A) more slender than that of female and 0.71 mm long. Greatest width 221 mm. Urosome six-segmented. Genital somite 103Ö 88 mm, longer than wide. Anal somite about as long as wide and distinctly longer than pre-anal somites. Caudal ramus short compared with that of female, 4.60 times as long as wide.

Antennule with three additional aesthetascs: two on second and one on third segments as indicated by dark dots in ®gure 23D. Antenna with four setae on third segment.

Mandible, maxillule and maxilla as in female. Maxilliped (®gure 25C) consisting of three segments and terminal claw. First and third segments unarmed. Second segment with spinules on entire inner margin and two setae at posterior slightly distal to midlength of segment; one of these two setae transformed as in ®gure 25C. Claw slender, evenly curved, nearly as long as three proximal segments combined, proximally with one minute setule and one large seta.

Legs 1±4 as in female. Free segment of leg 5 quadrangula r (®gure 25D), 17 Ö 9 mm (1.89:1), terminally with one spinule, one naked seta (39 mm) and one spine (29 mm). Leg 6 represented by two setae on posterior corner of genital ¯ap.

Etymology. The speci®c name bullatus is Latin, meaning`ināted’. It alludes to the ināted free segment of female leg 5.

Remarks. The genus L ichomolgus comprises 26 species, including the most recently recorded L. hoi Stock, 1995 . L ichomolgus bullatus n. sp. is easy to di erentiate from all congeners by the unique greatly dilated free segment of leg 5. In the description of L. hoi, Stock (1995) emphasized the ināted inner margin of the same segment of leg 5 as a conspicuous feature of this species. This inātion is more pronounced in L. bullatus and cannot be confused with L. hoi or any other known species of L ichomolgus .

Figures

FIG. 23. L ichomolgus bullatus n. sp., female: (A) habitus, dorsal; (B) urosome, dorsal; (C) distal part of urosome, ventral; (D) antennule; (E) antenna; (F) mandible; (G) maxillule. Scales: A =0.1 mm; B±E= 0.05 mm; F, G = 0.02 mm.