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 Dyspontius alatus n. sp. ( Figs. 5 , 6 ) Material examined. One$( holotype ) from a sponge, in the depth of 50 m , off Munseom in Seogwipo (approximately 33°12′40″N , 126°34′30″E ), Jeju Island , 12 October 2013 , collected by S.H. Kim. Holotype ($, dissected and mounted on a glass slide, NIBRIV0000680700 ) has been deposited in NIBR , Incheon , Korea . Female. Body ( Fig. 5A ) moderately broad and 838 μm long. Cephalothorax 461 × 482 μm, slightly wider than long, with weakly produced anterior apex ( Fig. 5F ) and pointed posterolateral corners. Dorsal tergites of somites ornamented with simple or 2­6­branched (5­branched one being most common) setules ( Fig. 5C, D ). Second and third pedigerous somites much narrower than cephalothorax, 72 × 338 and 61 × 294 μm, respectively, with their epimeral regions ( Fig. 5C ) markedly extending posterolaterally. Fourth pedigerous somite distinctly reduced, similar to fifth pedigerous somite in size and 136 μm wide. Urosome ( Fig. 5B ) 5­segmented. Fifth pedigerous somite 123 μm wide, tapering laterally, with pointed lateral apices. Genital double­somite 100 × 191 μm, consisting of expanded anterior and narrower posterior parts; anterior part characteristically with wing­like, broad epimera extended over posterior margin of somite; margins of epimera rounded. Three abdominal somites 31 × 72, 27 × 66, and 42 × 65 μm, respectively. Caudal ramus ( Fig. 5E ) 35 × 27 μm, 1.30 times as long as wide, armed with 6 setae and ornamented with setules on inner margin; inner dorsal seta (seta VII ) naked, other 5 setae plumose. Rostrum ( Fig. 5F ) longer than wide, strongly sclerotiz­ ed, with rounded posterior margin. Antennule ( Fig. 5G ) 252μm long and 9-segmented; first segment 54 μm long; second segment, longest, 61 μm long; armature formula 1, 9, 1, 6, 2, 2, 2, 2, and 11 + aesthetasc; aesthetasc on terminal segment slightly more than 1/3 times as long as antennular length. Antenna ( Fig. 5H ) with short, unarmed coxa; basis 35 × 17 μm, with fine setules at proximal region and on outer margin; exopod small, tipped with 2 unequal setae; first endopodal segment 31 × 14 μm, unarmed, but ornamented with setules on outer margin; second endopodal segment 29 × 13 μm, armed with 1 lateral and 2 distal setae, 1 elongate distal spine (67 μm long), and ornamented with rows of setules. Oral siphon ( Fig. 5I ) relatively broad, 327 μm long, extending beyond base of maxilliped but not reaching leg 1; distal apex setulose. Mandbile represented by stylet bearing several teeth and spinules distally ( Fig. 5J ). Maxillule ( Fig. 6A ) bilobed; inner lobe 62 μm long, with 2 small naked apical setae of equal length (15 μm long); outer lobe 46 μm long, with 2 large, spinulose setae (larger one 59 μm long) and 1 small naked seta. Maxilla ( Fig. 6B ) 2­segmented; syncoxa unarmed; basis slender, with 1 small seta and row of minute spinules in distal region; terminal claw clearly defined from basis, with rows of spinules. Maxilliped ( Fig. 6C ) 6­segmented; armature formula 1, 1, 2, 0, 1, and 1 + claw; syncoxa (first segment) with nipple­shaped projection at inner distal corner; basis also with nipple­shaped projection at proximal third and with numerous minute spinules along distal third of inner surface; inner seta on basis small and located at distal third of segment; terminal claw more than twice as long as terminal endopodal segment, with fine spinules along inner margin. Legs 1­3 biramous, with 3­segmented rami ( Fig. 6D, E ). Leg 4 ( Fig. 6F ) with 3­segmented exopod; endopod absent. Leg 1 ( Fig. 6D ) lacking inner element on basis; first exopodal segment with thick setules on outer margin; second exopodal segment characteristically lacking outer spine. Leg 2 ( Fig. 6E ) with dentiform process on posterior margin of basis between rami. Legs 3 and 4 lacking inner seta on coxa. Armature formula for legs 1­ 4 as follows: Coxa Basis Exopod Endopod Leg 1: 0­1 1­0 I­1; 0­1; II, 2, 3 0­1; 0­2; 1, 2, 3 Leg 2: 0­1 1­0 I­1; I­1; III , I, 5 0­1; 0­2; 1, 1 + I, 3 Leg 3: 0­0 1­0 I­1; I­1; III , I, 5 0­1; 0­2; 1, 1 + I, 3 Leg 4: 0­0 1­0 I­1; I­1; III , I, 5 (Absent) Leg 5 ( Fig. 6G ) represented by 2 papillae tipped with 1 plumose and 2 small, naked setae, respectively, on ventral surface of fifth pedigerous somite. Leg 6 ( Fig. 6G ) represented by 3 unequal setae, including minute one, on genital operculum. Fig. 5. Dyspontius alatus n. sp. , female. A, habitus, dorsal; B, urosome, ventral; C, left epimera of second and third pedigerous somites, dorsal; D, ornamentations of tergites of somites; E, anal somite and caudal rami, dorsal; F, rostral area, ventral; G, antennule; H, antenna; I, oral siphon; J, distal part of mandible. Scale bars: A, 0.1 mm; B, C, F, G, I, 0.05 mm; E, H, 0.02 mm; D, J, 0.01 mm. Fig. 6. Dyspontius alatus n. sp. , female. A, maxillule; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 4; G, right side of proximal part of urosome, ventral. Scale bars: A, D, G, 0.02 mm; B, C, E, F, 0.05 mm. Male. Unknown. Etymology. The specific name alatus is a Latin meaning “winged”, alluding to the possession of the wing­like epimera of the genital double­somite. Remarks. By having 2 spines plus 4 setae on the third exopodal segment of leg 1 and a well­developed exopod in uniramous leg 4, the new species is included in the genus Dyspontius Thorell, 1860 . The new species reveals three outstanding morphological features that are not observable in six congeners, as follows: (1) the genital double­somite has well­developed, wing­like epimera; (2) the basis of leg 1 lacks an inner distal seta; and (3) the second exopodal segment of leg 1 lacks an outer spine. The presence of the wing­like epimera of the genital double­somite is a characteristic feature of the genus Pteropontius Giesbrecht, 1895 , but the new species is not related to Pteropontius , because in this genus the segmentation and setation of leg 1 are reduced, with at most 2­segmented exopod.