Prohatsckekia pseudocremouxi sp. nov.

(Figs. 1–11)

Type material. Holotype ♀ (dissected and mounted on a glass slide; reg. no. NIBRIV0000266711) and paratype ♀ (preserved in ethanol; reg. no. NIBRIV0000266712), collected from the gills of five specimens of Scorpaena neglecta (Actinopterygii, Scorpaeniformes, Scorpaenidae), captured north off Jeju Island (33º43’47”N, 126º48’16”E), Korea, at 102 m depth.

Description of female. Body comprising distinct cephalothorax, short neck region consisting of second and third pedigerous somites, and trunk (Fig. 1). Body (Fig. 1) 1.38 (paratype)–1.45 (holotype) mm long. Cephalothorax (Fig. 1) (253 × 346 µm), 1.36 times wider than long: dorsal cephalothoracic shield with frontal margin produced, slightly concave in mid-line, rounded laterally and well defined posteriorly; shield with conspicuous cuticular strengthening bars visible externally. Parabasal papillae on anterior margin of cephalothorax simple, anteriorly-directed, visible in dorsal view (arrowed in Fig. 1). Neck region formed by narrow second and third pedigerous somites, merging into board, slightly dorsoventrally flattened trunk. Trunk (Fig. 1) ovoid (937 × 506 µm), about 1.85 times longer than wide, with swollen posterodistal margins. Abdomen (Fig. 2) wider than long (121 × 153 µm). Caudal rami (Fig. 1) longer than wide (59 × 34 µm), carrying one lateral and five terminal setae. Egg sac (Fig. 3) 1.64 mm long, containing 19 eggs.

Antennule (Fig. 4) 328 µm long, indistinctly 7-segmented; armature formula: 10, 6, 4, 2, 1, 3 + aesthetasc, 9 + aesthetasc. Antenna (Fig. 5) 3-segmented; basal segment unarmed; middle segment elongate, with single seta proximally and entire surface with fine, transverse cuticular ridges; distal segment strongly curved with transverse cuticular ridges in proximal half, subchela with two inner setae, one proximally and one near base of claw. Mandible (Fig. 6) forming stylet with pointed tip, marginal teeth lacking. Maxillule (Fig. 7) bilobate; anterolateral lobe with two small setae; posterior lobe longer, with two long distal setae. Maxilla (Fig. 8) 4-segmented, proximal segment unarmed; second segment largest, with long proximal seta on inner margin; third segment slender, with small distal seta on inner margin; distal segment bearing small inner seta at base of bifid claw. Maxilliped absent.

Legs 1–3 (Figs. 9–11) with coxa and basis largely fused, biramous. Exopods incompletely segmented. Setae on rami usually plumose.

Armature formula as follows: Leg 1 (Fig. 9) exopod indistinctly 2-segmented; endopod unsegmented and ornamented with eight complete and incomplete transverse cuticular ridges on anterior and posterior surfaces. Leg 2 (Fig. 10) exopod indistinctly 2- segmented, proximal segment of exopod with tiny spinules on inner and outer margin, distal segment of exopod with four transverse cuticular ridges on anterior surface; endopod 2-segmented and ornamented with three transverse cuticular ridges, distal segment with eight incomplete transverse cuticular ridges on anterior and posterior surfaces. Leg 3 (Fig. 11) exopod distinctly 2-segmented and ornamented with tiny spinules on inner and outer margins of proximal segment, distal segment with four incomplete transverse cuticular ridges on anterior and posterior surfaces; endopod 2-segmented and ornamented with tiny spinules on inner and outer margin of proximal segment; four transverse cuticular ridges on anterior surface of distal segment. Leg 4 (arrowed in Fig. 1) represented by one seta located posteriorly at 2/3 distance along trunk. Leg 5 absent.

Male. Unknown

Etymology. The name of the new species refers to its morphological similarity with Prohatschekia cremouxi Nunes-Ruivo, 1954.