Phyllopodopsyllus busanensis, Lee & Yoo & Kim, 2017

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, Two new Phyllopodopsyllus (Copepoda, Harpacticoida) from Korean marine interstitial, Journal of Species Research 6, pp. 185-214 : 201-208

Phyllopodopsyllus busanensis sp. nov.

( Figs. 1C and 11-15)

Type locality. Korea, East Coast, Gyeongnam-do province, Busan, Songjeong Beach , intertidal sand, interstitial water from a Karaman-Chappuis hole, 35°10.741 ʹ N 129°12.317 ʹ E .

Specimens examined. Holotype female ( NIBR IV 0000287280 ) dissected on one slide; paratype female ( NIBR IV 0000287281 ) in toto on one SEM stub; both collected from the type locality, 6 May 2016, leg. T. Karanovic.

Etymology. The species is named after the type locality, the city of Busan in South Korea. The name is an adjective for place, made with the Latin suffix “-ensis”.

Description. Female (based on holotype and one paratype). Total body length, measured from tip of rostrum to posterior margin of caudal rami (excluding caudal setae and appendages) from 405 (holotype) to 450 μm. Colour of preserved specimen light brown ( Fig. 1C). Nauplius eye not visible. Segmentation as in previous species. Habitus ( Figs. 1C, 11A) cylindrical but much

100 µm

less slender than in previous species, without distinct demarcation between prosome and urosome in dorsal view, but with sharp bend in lateral view; prosome/urosome ratio about 0.9; greatest width at posterior end of cephalothorax; cephalothorax only 1.2 times as wide as genital double-somite in dorsal view. Body length/ width ratio about 4.2. Free pedigerous somites without pronounced lateral or dorsal expansions. Integument of all somites relatively well sclerotized, generally smooth, covered with numerous shallow cuticular pits (see Figs. 11C, 12G); free prosomites and all urosomites additionally covered by parallel rows of minute and slender spinules; cephalothorax devoid of spinules. Hyaline fringe of all somites narrow and coarsely serrated. Surface of somites and caudal rami with total maximum of 185 cuticular organs (29 pairs of cuticular pores, 58 pairs of sensilla, one unpaired dorsal sensillum, and ten unpaired dorsal pores). All sensilla and pores homologous to those in previous species, with only small differences in their relative position; only real difference in cuticular organs visible on fifth urosomite (pore U5-II absent; see Fig. 13C) and caudal rami (additional pore Cr-III pres-

A B C D G H E F

100 µm

December 2017 KARANOVIC-NEW SPECIES OF PHYLLOPODOPSYLLUS FROM KOREA 205

ent; see Figs. 12G, 13B); pore Ct-XI larger than in previous species (see Fig. 11F) and sensilla U1-3 and U1-4 closer to each other (see Fig. 12B).

Rostrum ( Fig. 11C) as in previous species small, weakly demarcated at base from cephalothorax, linguiform, about as wide as long, its anterior tip hardly reaching beyond anterior margin of lateral wings of cephalothoracic shield, with single dorsal pair of sensilla (Ct-1) at about 2/3 of its length.

Cephalothorax ( Fig. 11 B-E) smooth, cylindrical in dorsal view, tapering towards anterior end in lateral view, about 1.5 times as long as wide in dorsal view (including rostrum); representing 33% of total body length. Hyaline fringe of cephalothoracic shield narrow, serrat- ed dorsally, smooth laterally.

Pleurons of first free prosomites ( Fig. 11G, H) shorter than in previous species and densely covered by slender spinules, with only small lateral surface free of them.

All urosomites ( Fig. 12 A-F) also densely covered by slender spinules, and more so on dorsal than on ventral side.

Genital double-somite ( Figs. 12A, C, 13 A-C) only slightly longer than wide in ventral view, with finely serrated dorsal fringe and lateral internal ridges as only evidence of ancestral segmentation. Genital complex ( Fig. 13C) with single large and round copulatory pore in distal part of second urosomite, short and narrow copulatory duct, two small and ovoid seminal receptacles in central part of second urosomite, and central genital aperture in anterior part of second urosomite; aperture covered by reduced sixth legs.

Fourth urosomite ( Figs. 12D, E, 13 A-C) with hyaline fringe smooth ventrally.

Sixth urosomite ( Figs. 12F, 13 A-C) slightly narrower and significantly longer than fifth urosomite, cleft medially in posterior part, with posterior row of spinules; anal operculum broad but less so than in previous species, also longer and more convex, with finely serrated posterior margin, representing about 46% of somite’s width; anal sinus as in previous species.

Caudal rami ( Figs. 12F, G, 13 A-C) strongly sclerotized, cylindrical but with strong dorsal ridge, with slightly inflated posterior ventro-outer corner, with slender spinules along outer-dorsal surface but without spinules along inner margin, about 1.8 times as long as greatest width in ventral view and nearly 1.7 times in lateral view, with narrow space between them; ornamented three lateral pores, two of them homologous to those in previous species (Cr-I and Cr-II); armed as in previous species with seven setae but no setae fused basally, anterior lateral setae inserted slightly more anteriorly, longer inner apical seta, and central apical seta with bulbous base; novel pore (Cr-III) situated between two other pores; doral seta marking end of dorsal ridge.

Antennula ( Figs. 11C, D, 14A) nine-segmented, about as long as cephalothorax, with prominent integumental beak on second segment, with robust and long aesthetasc on fourth segment fused basally to slightly longer seta, slender and much shorter apical aesthetasc on ninth segment fused basally to two slightly longer setae, and setal formula 1.9.7.4.2.4.2.2.7. All setae slender and smooth; one lateral seta on seventh and eight segments and four lateral setae on sixth segment biarticulate. Only ornamentation short arched row of spinules at base of first segment, on dorso-median surface. Length ratio of antennular segments, from proximal end and along caudal margin, 1: 0.4: 0.2: 0.2: 0.15: 0.15: 0.1: 0.1: 0.4. First segment also strongest, about 2.9 times as long as wide; fourth segment with prominently protruded anteri- or distal corner at base of large easthetasc.

Antenna ( Figs. 11D, 14B) slenderer than in previous species, but with same segmentation and armature. Coxa 0.8 times as long as wide, unornamented. Allobasis 2.5 times as long as wide and about three times as long as coxa, ornamented with longitudinal row of minute spinules along inner margin. First endopodal segment 2.4 times as long as wide and about as long as allobasis, ornamented with single transverse arched row of minute spinules in proximal part. Second endopodal segment most robust, slightly slenderer proximally but also generally cylindrical, 3.7 times as long as wide, 1.4 times as long as first endopodal segment, with two surface frills distally and row of small spinules along inner margin. Exopod slender, cylindrical but slightly curved, about 3.6 times as long as wide and half as long as allobasis, unornamented; outer apical seta strongest and spiniform, fused basally to exopod, about 1.3 times as long as inner apical seta, and 0.8 times as long as lateral seta.

Labrum as in previous species, not mounted properly for drawing.

Mandibula ( Figs. 11D, 14C) segmentation, general shape, and most armature and ornamentation as in previous species, but endopod proportionately smaller and exopod much larger and armed with three apical setae. Basis twice as long as wide. Endopod 3.9 times as long as wide, 0.7 times as long as basis, and 1.4 times as long as exopod. Exopod cylindrical, very slender, 4.8 times as long as wide, unornamented, armed with one lateral and four apical slender and smooth setae.

Maxillula ( Fig. 14 D-F) segmentation, general shape, and most armature and ornamentation as in previous species, but praexocal arthrite armed apically only seven elements, and coxa without outer seta but with five inner elements (one strong and geniculate, four slender and smooth); endopod about 2.7 times as long as wide.

Maxilla ( Fig. 14G) segmentation, general shape, armature, and ornamentation as in previous species.

Maxilliped ( Figs. 12H, 14H) segmentation, general shape, and most armature and ornamentation as in previous species, but all spinules shorter and endopod armed with additional smooth and slender seta. Syncoxa 2.5 times as long as wide, cylindrical, and only slightly restricted in central part. Basis 3.4 times as long as wide and 1.1 times as long as syncoxa, cylindrical but wider in central part. Endopod nearly three times as long as wide and 0.3 times as long as basis, cylindrical but narrower in proximal half; apical spine 2.2 times as long as basis and 1.6 times as long as subapical seta.

Swimming legs ( Fig. 15 A-D) slightly shorter and less slender than in previous species, but with same segmentation, general shape, most ornamentation and armature.

First swimming leg ( Fig. 15A) with prehensile endopod as in previous species, but coxa and basis wider, fist endopodal segment shorter and additionally armed with inner seta, and first exopodal segment with inner bulge. Coxa 0.8 times as long as wide, narrower in distal part than proximal, with short outer spiniform process, ornamented with three anterior and one posterior row of spinules. Basis about as long as wide, inner spine slightly stronger and about 1.4 times as long as outer. Exopod with first segment longest and third shortest; inner geniculate seta on third segment 1.3 times as long as entire exopod and about 1.6 times as long as outer geniculate seta. Endopod longer than exopod; first endopodal segment 1.15 times as long as entire exopod, more than six times as long as wide, and 3.1 times as long as second endopodal segment; endopodal apical seta as long as exopodal outer apical seta but slightly stronger, and about 1.4 times as long as apical endopodal spine.

Second swimming leg ( Fig. 15B) with all segments shorter than in previous species, with two large spiniform processes on basis, and additionally armed with inner spiniform seta on first endopodal segment, as well as with inner slender seta on third exopodal segment. Coxa 0.7 times as long as wide, ornamented with six rows of small spinules on anterior surface and one row of spinules on posterior surface. All exopodal segments of similar length. Endopod about 0.6 times as long as exopod, first segment 0.8 times as long as second but much wider; apical edopodal spine about 0.7 times as long as endopod, 0.6 times as long as central slender seta, and less than half as long as inner apical seta.

Third swimming leg ( Fig. 15C) very similar to second, except slightly slenderer and with longer inner seta on first endopodal segment; endopod 0.4 times as long as exopod; first endopodal segment 0.7 times as long as second endopodal.

Fourth swimming leg ( Fig. 15D) very similar to previous species, except for spiniform processes on basis.

Fifth leg ( Figs. 1A, 12A, C, D, 15E) shape, segmentation, and armature as in previous species, but covered by dense spinules in outer part, with serrate outer margin and smooth distal margin; short exopodal setae smooth or sparsely pinnate; forming brooding chamber with genital double-somite and anterior part of fourth urosomite normally containing six to seven eggs.

Sixth leg ( Fig. 13C) shape and ornamentation as in previous species; also armed with three setae, but outermost seta extremely slender and shortest, while central seta longest, pinnate, not reaching posterior margin of genital double-somite, and more than twice as long as innermost pinnate seta.

Male unknown.

Variability. No obviously variable structures were observed between the two collected females, but the comparison was hindered by the fact that they were examined by different methods: the holotype was dissected and studied using light microscopy, while the paratype was permanently mounted on an SEM stub.