Koreacyclopina wellsi, Karanovic, 2021

Karanovic, Tomislav, 2021, Two new marine cyclopinids (Crustacea: Copepoda: Cyclopoida) from interstitial habitats in Korea, Zootaxa 5051 (1), pp. 319-345 : 331-340

Koreacyclopina wellsi sp. nov.

Type locality. Korea, East Coast , Uljin, beach, intertidal sand, 36°18.309’N 129°22.648’E .

Specimens examined. Holotype female dissected on one slide, allotype male dissected on one slide, four paratypes (three females and one male) dissected on one slide each, two paratypes (one female and one male) in alcohol, and two paratype females on one SEM stub (together with other specimens of Koreacyclopina wellsi and with specimens of Heterocyclopina koreaensis ; row no. 1), all collected from the type locality, 6 May 2016, leg. T. Karanovic.

Two paratypes (one female and one male) dissected on one slide each, five female paratypes on one SEM stub (together with other specimens of Koreacyclopina wellsi and with specimens of Heterocyclopina koreaensis ; row no. 3), and 15 paratypes (nine females, three males, and three copepodids) in alcohol, all collected from Korea, West Coast, Wido Island, beach, intertidal sand, 35°35.089’N 126°15.196’E, 12 April 2013, leg. T. Karanovic .

Etymology. The species is named in honour of the late Prof. John Wells, in recognition of his contributions to the taxonomy of cyclopinid copepods ( Wells 1965, 1967), which perhaps remained in the shadow of his colossal contributions to the taxonomy and systematics of harpacticoid copepods ( Wells 2007).

Description. Female (based on holotype and 12 paratypes). Body length, from 525 to 540 μm. Colour of preserved specimens yellowish and nauplius eye not visible. Integument on all somites smooth ( Figs 8 , 9 ), with very little bacterial cover, minute 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 ursomites serrated. Habitus ( Figs. 8A , 9A ) relatively slender in dorsal view, but with pronounced distinction between prosome and urosome (especially in lateral view), prosome ovoid, about 1.3 times as long as urosome, greatest width in dorsal view at posterior end of cephalothorax. Body about 3.3 times as long as wide in dorsal view and cephalothorax twice as wide as genital double-somite. First pedigerous somite not fused to cephalothorax, but completely covered with posterior extension of cephalothoracic shield (see Fig. 8C ). Pedigerous somites without lateral expansions. Rostrum ( Fig. 8B ) well-developed, membranous, very broad. Cephalothorax ( Figs. 8A, B, C , 9A, B, C ) 1.3 times as long as wide, about twice as long as free prosomites combined, representing around 38% of body length. Second to fourth prosomites ( Figs. 8D, E , 9D, E ) progressively shorter and narrower towards posterior end, and with fewer cuticular organs.

First urosomite ( Figs. 9F ) shortest, laterally expanded in posterior part.

Genital double-somite ( Figs. 8F , 9G , 11A, B, C ) about 1.15 times as long as wide in ventral view, widest anterior part 1.4 times as wide as posterior margin; anterior part (second urosomite) with one pair of narrowly spaced dorsal sensilla, dorsal median pore, and one pair of lateral pores next to sixth legs; posterior part (third urosomite) with one pair of narrowly spaced dorsal sensilla, one pair of lateral sensilla, and two pairs of widely spaced ventral pores. Median copulatory pore inside large depression, small, triangular, covered by large triangular flap formed by glued spermatophores. Copulatory duct short, narrow, rigidly sclerotized, directed anteriorly and extended anteriorly past seminal receptacles. Seminal receptacles very small, ovoid, spaced widely and forming cross-like structure with copulatory duct, slightly less rigidly sclerotized than copulatory duct, without internal folds. Oviducts not rigidly sclerotized and therefore not clearly visible. Genital aperture situated laterally, covered by reduced sixth legs. Fourth urosomite ( Figs. 9G , 11A ) with sensilla and pores as in third urosomite, except ventralmost pair of pores more narrowly spaced. Fifth urosomite ( Fig. 8G , 9H , 11A ) with one pair of widely spaced ventral pores and one pair of lateral pores. Sixth urosomite ( Figs. 8H , 9H , 11A ) with one pair of large dorsal sensilla, one pair of lateral sensilla, one pair of dorsal pores, one pair of ventral pores, two diagonal rows of minute spinules in narrow and deep anal sinus; anal operculum very short, narrow, covered by posterior margin of fifth urosomite.

Caudal rami ( Figs. 8A , 9A, H , 10A , 11A ) cylindrical, about six times as long as wide, narrowest in central part, narrowly spaced on anal somite, slightly diverging posteriorly, with pair of ventrolateral pores around midlength, minute spinules at base of lateral and outer apical setae, posterior ventral row of large spinules, and seven setae. Almost all setae broken in all examined specimens, so their size could only be estimated from width of remaining basal part; all except dorsal seta uniarticulated at base; dorsal seta inserted close to median posterior corner, biarticulated at base; anterior lateral seta minute, hardly larger than some sensilla, inserted at about two fifths of ramus length; posterior lateral inserted dorsolaterally at about three quarters of ramus length; principal apical setae with breaking planes.

Antennula ( Figs. 8A , 9A , 10D , 11D, E ) reaching two thirds of cephalothoracic shield with its distal tip, stout, cylindrical but tapering towards distal end, 13-segmented but second segment with signs of incomplete segmentation along posterior margin, with most setae smooth and slender and both aesthetascs short and slender, row of small spinules only on first segment; armature formula 3.12.3.5.1.1.1.1.1+ae.2.2.6+ae; one large seta on tenth and one on thirteenth segment with breaking planes, only two subapical setae on thirteenth segment biarticulated; second segment largest and longest, about 0.9 times as long as wide; tenth segment second longest, about 1.1 times as long as wide; thirteenth segment 1.7 times as long as wide, about as long as eleventh and twelfth segments combined.

Antenna ( Figs. 10F , 11F ) slender, cylindrical, five-segmented, composed of short coxa, long basis, and even longer three-segmented endopod; coxa half as long as wide, unarmed and unornamented; basis 2.6 times as long as wide, with longitudinal row of minute spinules along outer margin, several large spinules on inner margin, one inner and two outer (expodal) slender and smooth setae; first endopodal segment 0.7 times as long as basis, 2.2 times 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 several longitudinal rows of small spinules along outer margin, and five setae on inner margin (one lateral and four subapical; one subapical seta spiniform, other slender); third endopodal segment slightly shorter than first endopodal, 3.2 times as long as wide, with tuft of spinules on outer distal corner, four strong prehensile apical setae, one slender apical seta, and two slender subapical setae.

Mandibula ( Figs. 10B, F , 12A ) as in previous species, except last exopodal segment with three setae, last endopodal segment longer, dorsalmost tooth on cutting edge shorter, most teeth on cutting edge multicuspidate, cutting edge with more spinules, and basis, endopod, and exopod with large spinules.

Maxillula ( Figs. 10B , 12B, C ) as in previous species, except with extra slender seta on endopod, and also distal part of endopod more elongated (and consequently lateral setae inserted more proximally).

Maxilla ( Fig. 12D ) more tapering distally than in previous species but also 2.6 times as long as wide, unornamented, segmentation as in previous species, armature as in previous species, except proximal coxal endite with only two setae, third endopodal segment with only two setae, and distal basal seta (spine?) not fused to basis.

Maxilliped ( Figs. 10C , 12E ) as in previous species, except syncoxa with spinules along outer margin, third endopodal segment more elongated (2.3 times as long as wide and 0.8 times as long as second endopodal), and third endopodal segment with single prehensile seta (in total only four prehensile setae on endopod).

Swimming legs ( Figs. 10G, H , 13A, B, C, D, E, F ) segmentation, ornamentation, and most armature as in previous species, except second endopodal segment of fourth leg with two inner setae; third endopodal segment of fourth leg nearly 1.9 times as long as wide.

Fifth leg ( Figs. 8F , 10E , 13G ) segmentation and most armature and ornamentation as in previous species, except each segment with anterior cuticular pores, and second segment with additional outer spine.

Sixth leg ( Fig. 9G ) as in previous species, except slender seta much shorter.

Male (based on allotype). Urosome ( Fig. 14A ) as in previous species slightly more slender than in female, and second and third urosomites fully articulated, but ornamentation as in female; genital somite slightly longer than in previous species.

Caudal rami ( Fig. 14A ) significantly shorter than in female (about 4.3 times as long as wide), but armature and ornamentation without significant differences.

Antennula ( Fig. 14B ) shape, segmentation, geniculation, ornamentation, and most armature as in previous species, except ultimate segment comparatively shorter, and armature formula 1.1.7.2.2.2+ae.3.1.3+ae.4+ae.1.2.2.1+a e.10+2ae.

Antenna, mandibula, maxillula, maxilla, and maxilliped as in female.

Swimming legs ( Fig. 14C, D, E, F ) as in female, except third exopodal segment of second leg with distal spine fused with segment, short, and smooth.

Fifth leg ( Fig. 14A ) segmentation and most armature as in female, except second segment with two extra inner setae and apical seta much longer.

Sixth leg ( Fig. 14A ) as in previous species, but outer seta twice as long as central seta and inner spine.

Variability. One female from Wido with lateral pore on third pedigerous somite situated more anteriorly (almost in line with two central lateral sensilla). Flap formed by fused spermatophores remarkably uniform.

Figures

FIGURE 8. Koreacyclopina wellsi gen. et sp. nov., SEM photographs, all in lateral view; A & B, paratype female 1 from Wido; C-H, paratype female 2 from Uljin: A, habitus; B, anterior part of cephalothorax with rostrum and proximal part of antennula; C, posterior corner of cephalothoracic shield, partly overlapping free first pedigerous somite; D, tergite of second pedigerous somite; E, tergite of third pedigerous somite; F, first urosomite and genital double-somite (fused second and third urosomites), with fifth legs and attached spermatophores; G, fourth urosomite; H, sixth urosomite.

FIGURE 9. Koreacyclopina wellsi gen. et sp. nov., SEM photographs, all in dorsal view; A & B, paratype female 3 from Wido; C-H, paratype female 4 from Uljin: A, habitus; B, posterior median part of cephalothorax; C, anterior tip of cephalothorax; D, second pedigerous somite; E, third and fourth pedigerous somites; F, first urosomite; G, genital double-somite (fused second and third urosomites) and fourth urosomite; H, fifth and sixth urosomites with anterior part of caudal rami.

FIGURE 10. Koreacyclopina wellsi gen. et sp. nov., SEM photographs, A-C, paratype female 2 from Uljin; D & E, paratype female 1 from Wido; F, paratype female 5 from Wido; G & H, paratype female 6 from Wido: A, anterior part of caudal rami in lateral view; B, mandibular palp, maxillula, and maxilla; C, maxilliped; D, distal part of antennula; E, fifth legs; F, antenna and mandibular palp; G, endopod of first swimming leg; H, exopod of first swimming leg.

FIGURE 11. Koreacyclopina wellsi gen. et sp. nov., holotype female, line drawings: A, urosome, ventral view; B, gonopore and seminal receptacles, without spermatophores; C, spermatophores, removed from urosome and flattened; D, left antennula; E, distal tip of right antennula; F, antenna.

FIGURE 12. Koreacyclopina wellsi gen. et sp. nov., holotype female, line drawings: A, mandibula; B, maxillular gnathobase; C, maxillular palp; D, maxilla; E, maxilliped.

FIGURE 13. Koreacyclopina wellsi gen. et sp. nov., holotype female, line drawings: A, first swimming leg; B, second swimming leg, without last two endopodal segments; C, endopod of second swimming leg; D, intercoxal sclerite of third swimming leg; E, third endopodal segment of third swimming leg; F, fourth swimming leg; G, fifth leg, slightly awkwardly mounted.

FIGURE 14. Koreacyclopina wellsi gen. et sp. nov., allotype male, line drawings: A, urosome, ventral view; B, antennula; C, third exopodal segment of second swimming leg; D, second and third endopodal segments of second swimming leg; E, third exopodal segment of fourth leg; F, second and third endopodal segments of fourth swimming leg.