Two new marine cyclopinids (Crustacea: Copepoda: Cyclopoida) from interstitial habitats in Korea Author Karanovic, Tomislav text Zootaxa 2021 2021-10-12 5051 1 319 345 journal article 4039 10.11646/zootaxa.5051.1.14 af1563dd-f9bc-490a-a39b-1e23757e0e7b 1175-5326 5563668 6B276081-8960-4AED-B0AE-B907F9109D54 Heterocyclopina koreaensis sp. nov. ( Figs. 1–7 ) Type locality. Korea, South Coast, Bangjukpo, beach, intertidal sand, 34°37.826’N 127°47.574’E . Specimens examined. Holotype female dissected on one slide, collected from the type locality, 19 August 2013 , leg. T . Karanovic. Paratypes : one male ( allotype ) and two females dissected on one slide each, two females in alcohol, and two females on one SEM stub (together with specimens of Koreacyclopina wellsi ; row no. 2), all collected from Korea , West Coast , Jeonbuk-do , Gyeokpo-ri , Gyeokpo beach, intertidal sand, 35°37.953’N 126°28.118’E , 13 April 2013 , leg. T . Karanovic . Etymology. The species name refers to Korea . It is an adjective for place, made with the Latin suffix “ -ensis ” Description. Female (based on holotype and six paratypes ). Body length, excluding caudal setae, from 335 to 385 μm. Colour of preserved specimens yellowish and nauplius eye not visible. Integument on all somites smooth ( Figs 1 , 2 ), with light bacterial cover, spinules only on anal somite and caudal rami, cuticular pores on all somites, and sensilla on all but penultimate somite; hyaline fringes of prosomites smooth, of urosomites serrated. Habitus ( Figs. 1A , 2A ) slender in dorsal view and without pronounced distinction between prosome and urosome, distinction more pronounced in lateral view, prosome about 1.3 times as long as urosome, greatest width in dorsal view at posterior end of cephalothorax. Body about 4.8 times as long as wide in dorsal view and cephalothorax 1.5 times as wide as genital double-somite. First pedigerous somite not fused to cephalothorax, but its tergites partly covered with posterior extensions of cephalothoracic shield ( Fig. 1C ). Pedigerous somites without lateral expansions. Rostrum ( Fig. 1B ) well-developed, membranous, very broad. Cephalothorax ( Figs. 1A, B, C , 2A ) 1.6 times as long as wide, about 1.3 times as long as free prosomites combined, representing around one third of body length. Second to fourth free prosomites ( Figs. 1D, E, F , 2B, C, D ) progressively shorter and narrower towards posterior end and with fewer cuticular organs. First urosomite ( Fig. 2D ) shortest, laterally expanded in posterior part. Genital double-somite ( Figs. 2E , 3H , 4A, B ) about 1.3 times as long as wide in ventral view, widest anterior part nearly 1.3 times as wide as posterior margin; anterior part (second urosomite) with one pair of narrowly spaced dorsal sensilla ( Fig. 3H ), dorsal median pore, one pair of ventral pores next to copulatory pore ( Fig. 4A ), and one pair of lateral pores next to sixth legs ( Fig. 3G ); posterior part (third urosomite) with one pair of more widely spaced dorsal sensilla than in anterior part ( Fig. 2E ), dorsal median pore, one pair of ventral pores and sensilla each ( Fig. 4A ), two pairs of lateral sensilla, and one pair of lateral pores ( Fig. 4B ). Median copulatory pore ( Fig. 4A ) wide and short, situated in first quarter. Copulatory duct short, narrow, rigidly sclerotized, directed posteriorly. Seminal receptacles ( Fig. 4A ) small, ovoid, spaced very closely, even more rigidly sclerotized than copulatory duct, with internal folds, reaching more than half of anterior part of double-somite, together representing 37% of somite width. Oviducts not rigidly sclerotized and therefore not clearly visible. Genital apertures situated laterally, covered by reduced sixth legs. Fourth urosomite ( Figs. 1G , 2F , 4A, B ) with sensilla and pores as in third urosomite, except without median dorsal pore. Fifth urosomite ( Fig. 4A, B ) with single pair of widely spaced ventral pores. Sixth (anal) urosomite ( Figs. 1H , 2G , 4A, B ) with one pair of large dorsal sensilla, one pair of dorsal pores, diagonal rows of large spinules in shallow anal sinus, and posterior row of spinules; anal operculum very short, broad, covered by hyaline fringe of fifth urosomite. Caudal rami ( Figs. 2H , 3A, B , 4A, B ) cylindrical, about five times as long as wide, narrowly spaced on anal somite, diverging posteriorly, with pair of dorsolateral pores in last third, minute spinules at base of lateral and outer apical setae, posterior ventral row of large spinules, and seven setae. All setae slender and bipinnate, and all except dorsal seta uniarticulated at base; dorsal seta about 1.2 times as long as ramus, inserted very close to median posterior corner, biarticulated at base; anterior lateral seta smallest, about 0.7 times as long as one ramus width, inserted at first third of ramus length; posterior lateral seta 1.4 times as long as ramus width, inserted slightly anterior than second third of ramus length; outermost and innermost apical setae slightly shorter and more slender than posterior lateral seta; principal apical setae with breaking planes, inner one nearly four times as long as caudal ramus and twice as long as outer one. Antennula ( Figs. 1A, B , 3C , 4C ) reaching two thirds of cephalothoracic shield with its distal tip, stout, smooth, cylindrical but tapering towards distal end, 15-segmented but second segment with signs of incomplete segmentation along caudal margin, with most setae smooth and slender and all aesthetascs short and slender; armature formula (ae = aeshetasc) 3.14.2.2.2.1.1.1.1.0.2.2+ae.2.2+ae.6+ae; no setae with breaking planes, only three subapical setae on fifteenth segment biarticulated, one seta on fifth and one on sixth segment short and spiniform; second segment largest and longest, but incomplete segmentation suggesting fusion of at least four ancestral segments, about 1.3 times as long as wide; twelfth segment second longest, about 1.3 times as long as wide; fifteenth segment 1.5 times as long as wide, about as long as thirteenth and fourteenth segments combined. Antenna ( Fig. 5A ) slender, cylindrical, three-segmented but with some signs of ancestral five-segmented state; coxa minute, largely fused to allobasis, unornamented; allobasis with short surface suture along inner margin indicating ancestral segment boundary between basis first endopodal segment, twice as long as wide, unornamented, armed with one inner and one outer (exopodal) seta, both of similar length, about half as long as basis; first endopodal segment 0.8 times as long as basis, twice as long as wide, with spinules along outer convex margin, and with single inner seta; second endopodal segment slightly longer and more slender than first endopodal, with five inner setae (one lateral and four subapical; one subapical seta spiniform, other slender); third endopodal segment slightly shorter than first endopodal, 2.6 times as long as wide, with four strong prehensile apical setae, one slender apical seta, and two slender subapical setae. Mandibula ( Fig. 5B ) with large coxa, smaller basis, two-segmented endopod, and four-segmented exopod, although first exopodal segment with small incomplete suture; coxal gnathobase with relatively wide cutting edge consisting of large teeth (ventralmost largest), several small spinules in between teeth, and two setae at dorsal corner; dorsalmost seta on cutting edge unipinnate, about 1.6 times as long as other, smooth seta; basis 2.3 times as long as wide, with single inner seta; endopod 0.7 times as long as basis, with two setae on first and five setae on second segment; exopod slightly shorter than basis but much more slender, with armature formula 1.1.1.2. Maxillula ( Fig. 5C ) unornamented, composed of well-developed praecoxa and three-segmented palp; arthrite of praecoxa with six strong apical spines and three spiniform setae, proximalmost seta longest and strongest; palp slightly smaller than praecoxa, composed of large rectangular coxobasis, ovoid small endopod, and ovoid and even smaller exopod; coxobasis 2.3 times as long as wide, with single exopodal seta and four inner setae (two very strong and two slender); endopod as long as width of basis, about 1.4 times as long as wide, with two lateral and four apical slender setae; exopod 0.8 times as long as endopod, as long as wide, with four apical slender setae. Maxilla ( Fig. 5D ) stout, 2.6 times as long as wide, tapering towards distal end, unornamented, composed of praecoxa, coxa, basis, and three-segmented endopod; praecoxa largest, quadrate, with four setae on proximal endite and one seta on distal endite; coxa 0.7 times as long as praecoxa, also quadrate, with three setae on both proximal and distal endites; basis half as long as coxa, with basally fused, smooth and robust claw and two articulated setae, proximal seta strong and bipinnate, 1.5 times as long as claw, distal seta smooth and minute; endopod 1.5 times as long as basis, first segment twice as long as second and armed with two strong setae, second segment twice as long as third and armed with one strong seta and one short and smooth seta, third segment minute, with one strong and two slender setae. FIGURE 1. Heterocyclopina koreaensis sp. nov. , paratype female 1, SEM photographs, all in lateral view: A, habitus; B, anterior part of cephalothorax with rostrum and proximal part of antennula; C, posterolateral corner of cephalothoracic shield, partly overlapping free first pedigerous somite; D, tergite of second pedigerous somite; E, tergite of third pedigerous somite; F, tergite of fourth pedigerous somite; G, fourth urosomite; H, sixth urosomite with anterior part of caudal rami. FIGURE 2. Heterocyclopina koreaensis sp. nov. , paratype female 2, SEM photographs, all in dorsal view:A, habitus; B, second pereiopodal somite; C, third pedigerous somite; D, fourth pedigerous somite and first urosomite; E, genital double-somite (fused second and third urosomites); F, fourth urosomite; G, sixth urosomite; H, caudal rami. FIGURE 3. Heterocyclopina koreaensis sp. nov. SEM photographs; A-G, paratype female 1, lateral view; H, paratype female 2, dorsal view: A, anterior part of caudal rami; B, posterior part of caudal rami; C, distal part of antennula; D, first swimming leg; E, second swimming leg; F, fifth leg; G, sixth leg; H, anterior part of genital double-somite with left sixth leg. FIGURE 4. Heterocyclopina koreaensis sp. nov. , holotype female, line drawings: A, urosome, ventral view; B, urosome, lateral view; C, antennula. FIGURE 5. Heterocyclopina koreaensis sp. nov. , holotype female, line drawings: A, antenna; B, mandibula; C, maxillula; D, maxilla; E, maxilliped. FIGURE 6. Heterocyclopina koreaensis sp. nov. , holotype female, line drawings: A, first swimming leg; B, second swimming leg; C, third swimming leg; D, fourth swimming leg; E, fifth leg. FIGURE 7. Heterocyclopina koreaensis sp. nov. , allotype male, line drawings: A, urosome, ventral view; B, urosome, lateral view; C, antennula; D, fifth leg. Maxilliped ( Fig. 5E ) prehensile, slender, almost four times as long as wide, tapering in proximal half but cylindrical in distal half, seven-segmented, composed of syncoxa, basis, and five-segmented endopod; syncoxa almost ovoid, 1.7 times as long as wide, unornamented, with four elements on proximal endite and two on distal endite; basis half as long as syncoxa, with row of slender spinules on inner margin and two setae on only endite; first endopodal segment triangular, small, with single sender seta; second endopodal segment longest, cylindrical, twice as long as wide, with single slender seta; third endopodal segment half as long as second endopodal, 1.25 times as long as wide, with two prehensile setae; fifth endopodal segment twice as long as fourth endopodal, as long as wide, with two prehensile and two slender setae. Swimming legs ( Figs. 3D, E , 6A, B, C, D ) composed of short praecoxa, rectangular large coxa, triangular basis, three-segmented exopod, three-segmented endopod, and coxae of opposite appendages connected with intercoxal sclerite; coxae of all legs with pore on anterior surface, row of minute spinules on outer distal corner, and slender seta on inner distal corner; intercoxal sclerites with slightly concave distal margin, and all, except on first leg, with two parallel rows of spinules on posterior surface; basis with convex inner margin, slender outer seta, strong inner spine on first leg and short spiniform process instead on other legs, anterior pore (except on fourth leg), row of spinules at base of endopod, and spiniform process between exopod and endopod; all exopodal and endopodal segments with spinules along outer margin and also along distal margin on anterior surface, first exopodal segment also along inner margin; second endopodal and third exopodal segments with single cuticular pore each; first exopodal segment with single outer spine; second exopodal segment with outer spine and inner seta; first and second endopodal segments with single inner seta each; third endopodal segments seta formula 5.6.6.5; third exopodal segment seta formula 5.5.5.5 and spine formula 3.4.4.3; third endopodal segment of fourth leg 1.6 times as long as wide. Fifth leg ( Fig. 3F , 6E ) small, two-segmented, with short intercoxal sclerite; first segment 1.4 times as wide as long, with posterior row of minute spinules and single outer seta; distal segment slightly longer but much narrower than first, 1.4 times as long as wide, with spinules along both inner and outer margins, apical central seta and two subapical spines; inner spine about as long as apical seta, about 1.5 times as long as second segment or outer spine. Sixth leg ( Figs. 3G, H , 4B ) simple triangular cuticular plate, 1.6 times as wide as long, unornamented, with inner strong spine, which about 1.5 times as long as outer slender seta. Male (based on allotype ). Urosome ( Fig. 7A, B ) slightly more slender than in female, and second and third urosomites fully articulated, but ornamentation as in female. Caudal rami ( Fig. 7A, B ) slightly shorter than in female, but armature and ornamentation without significant differences. Antennula ( Fig. 7C ) longer and more robust than in female in comparison to cephalothorax, strongly digeniculate, 15-segmented, with proximal geniculation between ninth and tenth segments, and distal geniculation between thirteenth and fourteenth segments; armature formula: 1.1.9.2.2.1+ae.2.1.2+ae.3+ae.1.2.2.1+ae.10+2ae; thirteenth and fourteenth segments with strong cuticular ridges along anterior (geniculating) surface; eleventh, twelfth, and thirteenth segments with short spiniform seta each, all other setae slender and most also smooth. Antenna, mandibula, maxillula, maxilla, maxilliped, and all four swimming legs as in female. Fifth leg ( Fig. 7D ) three-segmented; first segment similar to female; second segment with single inner seta; third segment similar to second in female, but shorter and with one additional inner seta. Sixth leg ( Fig. 7B ) with inner spine and two slender setae; outer seta 1.4 times as long as central seta and 2.5 times as long as spine. Variability. The holotype (and only) female from Bangjukpo was larger and longer than any paratype female (all from Gyeokpo) (410 μm vs. 335-385 μm), but no other differences were observed.