Orthopsyllus ulsanus Back & Bang, 2026, sp. nov.

Orthopsyllus ulsanus sp. nov. Figs 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 Type locality. Subtidal, site D (35°29'27.67"N, 129°26'34.48"E, Fig. 1) using a grab sampler. Paratype was collected from site E (34°24'58.9"N, 127°54'20.4"E, Fig. 1). Type material. Holotype: • 1 ♀ (MABIK CR 00259122) dissected on ten slides. Paratype: • 1 ♂ (MABIK CR 00259121) dissected on eight slides. GenBank accession number. Mitochondrial cytochrome c oxidase subunit I genes (PX 210754, PX 210755, PX 485059 – PX 485064); 18 S ribonucleic acid genes (PX 218732, PX 218733, PX 485046 – PX 485049). Description. Female. Total body (Fig. 27 A, B), length from anterior margin of rostrum to posterior margin of caudal rami 1,040 μm, maximum width 170 μm measured at end of cephalothorax. Body (Fig. 27 A, B): cylindrical and not dorsoventrally depressed, with minute sensilla dorsally; rostrum well developed, defined at base, triangular, smooth at tip, with two sensilla; cephalothorax wider than free somites, several pits scattered on surface (Fig. 36 A), pleural areas of cephalic shield narrow and posterolateral angles rounded; second and third urosomites (genital double somite) separated dorsally and laterally fused ventrally but discontinuous internal chitinous rib indicating original segmentation (Fig. 27 B and Fig. 29 C), genital apparatus located mid-ventrally at anterior half of genital double somite, genital pores covered by P 6; complex of seminal receptacles paired, transparent cuticle (Fig. 29 B, C); anal operculum deeply curved, serrated (Fig. 29 D). Caudal rami (Figs 27 C, 29 C, D, 36 F): parallel, rectangular, approximately 1.3 × longer than maximum width; inner lamella ornamented with nine teeth; each ramus with seven setae: seta V normal, longest; seta VI bare at inner distal corner, longer than seta IV; seta VII bare, tri-articulated, all setae bare. A 1 (Fig. 28 A, B): four-segmented; seg – 2 with a wrinkled process; seg – 3 longest, with sub-cylindrical pedestal with ae fused at base to one naked seta; armature formula: 1 – [1], 2 – [9], 3 – [10 + (1 + ae)], 4 – [11]; apical ae not observed, but two apical long setae fused at base. A 2 (Fig. 28 C): three-segmented; coxa bare; allobasis with one abexopodal pinnate seta; exp one-segmented, with four pinnate setae; free enp with four spines, three geniculate setae, and one bare seta. Md (Fig. 30 A): gnathobase with one lateral seta and several blunt teeth, palp one-segmented with five setae, enp, and exp vestigial. Mxl (Fig. 30 B): praecoxa trapezoidal shape; arthrite well developed with one juxtaposed bare seta on anterior surface, one uni-pinnate seta laterally, and eight elements among distal margin; coxal endite with two setae; basis with three setae; enp incorporated in basis, represented by small protrusion with two pinnate setae; and exp represented by one seta. Mxa (Fig. 30 C): syncoxa with three slender endites; proximal endite incorporated into base, represented by one pinnate seta; second and third endites with two spines and one seta; allobasis produced into a strongly curved claw, accessory armature consisting of two bare setae and one spine; and enp represented by two bare setae (Fig. 36 C). Mxp (Fig. 30 D): three-segmented; syncoxa with two setae; basis elongate, bare; enp represented by recurved claw with two accessory bare setae near base (Fig. 36 B). P 1 (Fig. 31 A): coxa bare; basis with one outer and one inner pinnate seta; exp three-segmented; exp – 1 and exp – 2 each with one outer spine; exp – 3 with two outer setae and two brush setae; enp two-segmented; enp – 1 bare, ornamented row of long setules among inner margin; and enp – 2, with one seta and one brush seta (Fig. 36 D). P 2 (Fig. 31 B): coxa bare; basis with one outer seta; exp three-segmented; exp – 1 and exp – 2, each with one outer spine; exp – 3 with four spines and one minute seta; enp two-segmented; enp – 1, short, bare; enp – 2 with one inner pinnate, one apical longest, and one inner shortest seta. P 3 (Fig. 32 A): coxa bare; basis with one outer seta; exp three-segmented (Fig. 36 E); exp – 1 and exp – 2, each with one outer spine; exp – 3 with four spines and one minute seta; enp two-segmented; enp – 1, short, bare; and enp – 2 with three setae. P 4 (Fig. 32 B): coxa bare, basis with one outer seta; exp three-segmented; exp – 1 and exp – 2 each with one outer spine; exp – 3 with four spines and one minute seta; enp two-segmented; enp – 1, short, bare; enp – 2 with one inner pinnate, two apical setae, and outer strong pinnate seta. Armature formulae as follows: P 5 (Fig. 29 A): basal part with one outer bare seta; endopodal lobes not fused medially, connected by an intercoxal sclerite, with five pinnate setae; exp defined at base, with six pinnate setae. P 6 (Fig. 29 B): P 6 vestigial, represented by a small bump bearing two setae. Male. Total body (Fig. 33 A): length from anterior margin of rostrum to posterior margin of caudal rami 1,000 μm, maximum width 165 μm measured at end of cephalothorax. General body shape, ornamentation, and sensilla pattern as in female except for genital double somite; sexual dimorphism in A 1, P 3, P 4, P 5, and P 6. A 1 (Fig. 33 B – D): six segmented, robust, subchirocer; seg – 2 with small blunt process in middle; seg – 4 swollen, with two pad-like processes near anterior margin and two blunt processes: 1 – [1], 2 – [10], 3 – [8], 4 – [12 + (1 + ae)], 5 – [1], 6 – [10], apical ae absent, but two apical setae fused at base. P 2 (Fig. 35 A): similar to the one of female, except for one outer seta on basis shorter than females and innermost seta on enp – 2 longer than females. P 3 (Fig. 35 B): exp same as female; enp developed, three-segmented; enp – 1 short, bare; enp – 2 with long apophysis that apparently tri-segmented apically; and enp – 3 with one bare and two pinnate setae. P 4 (Fig. 35 C): similar to the one of female, except for enp – 2 with one apical (more robust than female), one bare, and two pinnate setae. P 5 (Fig. 34 A): benp represented by a small protrusion with two pinnate setae; exp defined at base with five setae. P 6 (Fig. 34 B): asymmetrical, with functional right member articulating at base and closing off genital aperture, and left member fused at base to genital somite; each P 6 with one bare and one pinnate seta. Caudal rami (Fig. 34 C, D): general shape same as in female; inner lamella ornamented with ten teeth. Etymology. The species name refers to the type locality.