Records of Adult Caligiform Copepods (Crustacea: Copepoda: Siphonostomatoida) in Marine Plankton from East Asia, Including Descriptions of Two New Species of Caligus (Caligidae) Author Venmathi Maran, B. A. Marine Ecosystem Research Division, Korea Institute of Ocean Science & Technology, Ansan P. O. Box 29, Seoul 425 - 600, Korea E-mail: bavmaran @ gmail. com & Takehara Marine Science Station, Setouchi Field Science Centre, Graduate School of Biosphere Science, Hiroshima University, 5 - 8 - 1 Minato-machi, Takehara, Hiroshima 725 - 0024, Japan E-mail: ohtsuka @ hiroshima-u. ac. jp bavmaran@gmail.com&ohtsuka@hiroshima-u.ac.jp Author Ohtsuka, Susumu Takehara Marine Science Station, Setouchi Field Science Centre, Graduate School of Biosphere Science, Hiroshima University, 5 - 8 - 1 Minato-machi, Takehara, Hiroshima 725 - 0024, Japan E-mail: ohtsuka @ hiroshima-u. ac. jp & Corresponding author ohtsuka@hiroshima-u.ac.jp Author Shang, Xu Wenzhou Medical College, Gao Jiao Yuan Qu, Chashan, Wenzhou, Zhejiang 325035, China text Species Diversity 2012 2012-11-25 17 2 201 219 https://www.jstage.jst.go.jp/article/specdiv/17/2/17_KJ00008425371/_article journal article 10.12782/sd.17.2.201 2189-7301 4649334 B59C9BBF-B456-4CD9-B646-88ECC92ED28B Caligus quadrigenitalis sp. nov. ( Figs. 2B , 3 , 4 ) Material examined . Holotype : Ovigerous ♀ (KMNH IvR 500,500), off Iheya Island , Ryukyu Islands , Okinawa Prefecture , Japan (St. 8), 22 May 2008 ( Table 1 ). Description . Female . Body ( Fig. 2B ) 3.34 mm long, excluding caudal setae. Cephalothorax suborbicular, 2.45× 2.40 mm , frontal plate ( Fig. 2C ) narrow. Fourth pediger almost entirely covered by cephalothorax, wider than long, 0.28× 0.43 mm . Genital complex rectangular, more than twice as wide as long, 0.67× 1.43 mm ; lateral surface with fine sensilla ( Fig. 2D ). Abdomen ( Fig. 2E ) small, rectangular, wider than long, 0.15× 0.27 mm , bearing sensilla near caudal region; tone quarter as long as genital complex. Caudal ramus ( Fig. 2F ) wider than long, 0.09× 0.12 mm , with 3 long terminal setae and 3 short subterminal setae. Egg string uniseriate, only present on one side, broken, containing 12 eggs . Antennule ( Fig. 2G ) 2-segmented; proximal segment distinctly longer than distal segment, armed with 27 setae; distal segment armed with subterminal seta on posterior margin and 11 setae plus 2 aesthetascs at tip. Antenna ( Fig. 3A ) 3-segmented; proximal segment large, with dentiform process on postero-medial surface, without armature elements; middle segment with single seta; distal segment drawn out into recurved claw bearing single seta. Postantennal process ( Fig. 2G ) weakly curved with membraneous flange, bearing 2 basal papillae, each with long setule; anoth- er similar papilla located nearby on sternite. Mandible ( Fig. 3B ) long, bearing 12 marginal teeth subapically. Maxillule ( Fig. 3A ) comprising tapering, dentiform posterior process with membraneous flange, and anterior papilla bearing 1 long and 2 short setae. Maxilla ( Fig. 3C ) 2-segmented, proximal segment large and unarmed; distal segment slen- der, bearing small, subterminal, hyaline membrane on outer edge, carrying 2 curved elements, each with strips of serrat- ed, hyaline membrane. Maxilliped ( Fig. 3D ) 3-segmented, proximal segment large and unarmed; middle segment indistinct; basal segment bearing medial seta, claw with seta at base ( Fig. 3E ). Sternal furca ( Fig. 3F ) with subquadrate box and bluntly pointed tines with well developed flanges. Fig. 2. Two species of Caligus from plankton samples. A, Caligus calotomi Shiino, 1954 , male (KMNH IvR 500,409), habitus, dorsal view. B–G, Caligus quadrigenitalis sp. nov. , holotype, female (KMNH IvR 500,500): B, habitus; C, frontal plate enlarged; D, lateral region of genital complex showing setules and leg 5; E, abdomen; F, caudal ramus; G, antennule. Scale bars: 1 mm (A, B), 0.2 mm (C), 0.1 mm (D–G). Armature on rami of legs 1–4 summarized in Table 2 . Leg 1 ( Fig. 4A ) protopod consisting of coxa with 2 setules, and basis with long, plumose outer seta and short, plumose inner seta; vestigial endopod tipped with setal vestiges; middle 2 of 4 terminal elements on distal margin of second exopodal segment bifid ( Fig. 4B ). Leg 2 ( Fig. 4C ) coxa ornamented with setule bearing papilla on anterior surface and large, plumose inner seta on posterodistal corner; basis with small, naked outer seta, bearing setule-bearing papilla on ventral surface; outer and medial margins of basis fringed with membrane; similar membrane on outer margin of proximal segment of exopod. Leg 3 ( Fig. 4D ) with protopod bearing small outer (basal) plumose seta and large inner (coxal) plumose seta, bearing spinules venterolaterally, free margins of both segments with marginal membranes, and margin with setules bearing papilla. Leg 4 ( Fig. 4E ) with long protopod, bearing outer plumose seta; exopod 2-segmented, first segment with long spine, reaching to midlength of distal segment; pecten present at base of each of 3 distal exopodal spine, these spines increasing in length distally ( Fig. 4E ). Leg 5 ( Fig. 2D ) represented by 2 papillae tipped, respectively with 2 and 1 pinnate setae and located on posterolateral margin of genital complex. Fig. 3. Caligus quadrigenitalis sp. nov. , holotype, female (KMNH IvR 500,500). A, antenna, postantennal process, and maxillule; B, mandible; C, maxilla; D, maxilliped; E, claw enlarged, maxilliped; F, sternal furca. Scale bars: 0.1mm. Remarks . This new species can be differentiated from its congeners by the following prominent features: (1) the genital complex is rectangular and more than twice as wide as long; (2) the fourth pedigerous somite is almost entirely covered by the posteriorly protruding margin of the cephalothorax; (3) the abdomen is small, only one-fourth the length of the genital complex; (4) the maxilliped has an extra, medial seta terminally; and (5) the exopod of leg 4 is armed with I-0, III long and slender spines. The extra seta on the maxilliped is also present in C. oviceps Shiino, 1952 and C. pampi Ho and Lin, 2002 ( Ho and Lin 2004a ), but, both of these differ markedly from C. quadrigenitalis in the sternal furca (curved tines in C. oviceps ; tines joined side-by-side in C. pampi ; vs bluntly pointed separate tines in the new species). The new species shares with C. orientalis Gusev, 1951 and C. polycanthi Gnanamuthu, 1950 a similarly small abdomen and a 2-segmented exopod with an armature of I-0; III on leg 4; with C. longispinosus Heegaard, 1962 the posterior margin of the cephalothorax that covers the fourth pedigerous somite and the same sort of leg 4 exopod; and with C. oculicola Tang and Newbound, 2004 a similarly small abdomen and again the segment of leg 4 ( Tang and Newbound 2004 ). C. quadrigenitalis can be differentiated from all four of these by the rectangular-shape of the genital complex and the extra seta of the maxilliped. Fig. 4. Caligus quadrigenitalis sp. nov. , holotype, female (KMNH IvR 500,500). A, leg 1; B, distal tip of exopod of leg 1 enlarged; C, leg 2; D, leg 3; E, leg 4. Scale bars: 0.1 mm (A–E), 0.05 mm (B). Table 2. Caligus quadrigenitalis sp. nov : armature on rami of legs 1–4 (Roman and Arabic numerals indicate spines and setae, respectively).
Coxa Basis Exopod Endopod
Leg 1 0-0 1-1 1-0; III, I, 3 (vestigial)
Leg 2 0-1 1-0 I-1, I-1, II, I, 5 0-1; 0-2; 6
Leg 3 0-1 1-0 I-0; I-1; III, 4 0-1; 6
Leg 4 0-0 1-0 I-0; III (absent)
Fig. 5. Caligus ogawai sp. nov. , holotype, female (KMNH IvR 500,501). A, habitus; B, caudal ramus; C, antennule; D, antenna, postantennal process and maxillule; E, mandible; F, maxilla; G, maxilliped; H, sternal furca. Scale bars: 1 mm (A), 0.1 mm (B–H), 0.05mm (D). Although many species in Caligus possess an armature of I-0, III on leg 4, only few have such long and slender spines, but these all differs greatly from C. quadrigenitalis in the shape of the genital complex: C. longipedis Bassett-Smith, 1898 (subquadrate with protruded corners), C. punctatus Shiino, 1954 (subrectangular and protruded), C. oviceps (slightly rounded with protruded corners), C. patulus Wilson, 1937 (subquadrate with protruded corners), C. pampi (large with posteriorly protruded, long abdomen), and C. planktonis Pillai, 1979 (long, broadly rounded) ( Ho and Lin 2004a , b). Etymology . The specific name, an adjective, is the combination of the Latin quadratus (=four cornered), and genitalis (=of the genital area), referring to the rectangular shape of the genital complex.