Glacioloxoconcha jeongokensis sp. nov.

Figs 4, 5, 6

Material examined.

Holotype, male, dissected on one slide (NIBRIV0000882303) and shell on micropaleontological slide (NIBRIV0000882313); Allotype, female, dissected on one slide (NIBRIV0000882309) and shell on micropaleontological slide (NIBRIV0000882311); Paratypes: one male and one female dissected on each slide, and shell on micropaleontological slides; ~ 20 specimens kept in 2 ml vial in 99% alcohol.

Type locality.

South Korea, Gyeonggi-do, Hwaseong-si, Seosin-myeon, Jeongokhang-ro, Yacht mooring. 37°11.179'N, 126°39.024'E, 25 October 2019, leg. Hyunsu Yoo & Byung-jin Yoo.

Etymology.

The species is named after the yacht mooring place from where it was collected.

Description.

Male. Carapace (Figs 4A, 6). Relatively small, L ~ 356 µm, H ~ 189 µm . RV overlapping LV dorsally. Carapace subquadrate form in lateral view (Figs 4A, 6A). Anterior margin rounded; dorsal margin straight; postero-dorsal margin with extended caudal process; ventral margin almost straight and inclined gently toward posterior margin; postero-ventral margin with two small spines (Figs 4A, 6A, F). Postero-ventral and anterior margins strongly compressed (Fig. 6A). Greatest H situated in front of middle. Eye present. Surface ornamentation consisting of shallow reticulation on postero-dorsal margin, with few simple setae; few sieve-like pores also present (Fig. 6A, B). Marginal pore canals distributed on antero-ventral and posterior margins (Fig. 4A). Posterior inner lamella wider than anterior. Muscular scar imprints consisting of a row of four vertical scars and one frontal scar. Hinge adont (Fig. 4A).

A1 (Fig. 4B). Six-segmented. First segment without setulae and setae. Second segment with setulae on antero-distal margin. Third segment with one bare seta antero-distally, reaching end of fourth segment. Fourth and fifth segments each with one bare seta on anterior-distal margin, reaching end of next segment. Terminal segment with three long bare setae on distal margin, almost 2.5 × longer than terminal segment. L ratios between six segments 2.5: 1.1: 1: 1.2: 1.5: 1.4.

A2 (Fig. 4C). Four-segmented. Exopod transformed into spinneret seta. First endopodal segment without setulae and seta. Second segment with one bare seta postero-distally reaching 2/3 length of third segment. Third segment with setulae on antero-proximal, postero-medial, and postero-distal margins, and with one bare seta on antero-proximal margin, reaching 1/2 length of the same segment; two bare setae postero-medially, reaching end of the same segment; one bare seta postero-distally, almost 2 × longer than terminal segment. Terminal segment with two strong, bare claws on distal margin almost 3 × longer than the same segment. L ratios between four segments 8.3: 3: 11.3: 1.

Md (Fig. 4F). Coxa with seven strong teeth and one thin, bare seta on distal margin, and one bare seta near anterior-distal margin. Exopod with three bare setae; endopod three-segmented. First endopodal segment with one bare seta antero-distally. Second segment with two bare setae antero-distally and one bare seta postero-distally. Terminal segment with nine setae, four of which arise from anterior margin, two from distal margin, and two from postero-distal margin. First segment almost 2 × longer than terminal segment.

Mxl (Fig. 4D, E). Palp present. Two-segmented. Terminal segment with four bare setae distally. Exopodite with 1 reflexed seta and ~ 14 bare setae on branchial plate. Masticatory process with three endites, first and second endites each with four bare setae, third endite with two bare setae.

L5 (Fig. 5A). Four-segmented. First segment with five bare setae, two antero-medially, one reaching and one not reaching end of the same segment; and two setae antero-distally, reaching 1/2 of second segment; and one postero-proximally, reaching 2/3 length of the same segment. Second segment with one bare seta antero-distally, reaching 1/3 length of the terminal segment. Penultimate segment without any seta. Terminal segment with one claw like seta on distal margin. Last three segments with setulae along anterior margin. L ratios between four segments 3.5: 1.9: 1: 1.4.

L6 (Fig. 5B). Four-segmented. First segment with three bare setae, one antero-proximally, reaching 1/2 length of the same segment; one tiny seta; and one antero-distally, reaching 1/5 length of second segment. Second segment with one bare seta antero-distally, reaching 1/3 length of terminal segment. Penultimate segment without any seta. Terminal segment with one claw-like seta on distal margin. Last three segments with setulae along anterior distal margin. L ratios between four segments 3.5: 2.8: 1: 1.8.

L7 (Fig. 5C). Four-segmented. First segment with four setae: one bare seta posterior-proximally, as long as 1/4 of the same segment; one bare seta on antero-proximally, as long as 1/4 of the same segment; one plumose seta antero-medially, reaching 1/4 length of second segment; one bare seta antero-distally, reaching 1/2 length of second segment. Second segment with one bare seta on anterior-distal margin, reaching 1/3 length of third segment. Third segment without seta. Terminal segment with one strong claw on distal margin, 1/2 as long as the segment. Last three segments with setulae along anterior margin. L ratios between four segments 3.2: 2: 1: 1.3. Compared with L5 and L6 segments, L7 is more elongated than L5, but similar to L6.

BO (Fig. 4G) With more than ten setae on distal margin. Positioned behind L7 and below Hp.

Hp (Fig. 5D). Basal plate sub-rectangular. Lobe rudimentary, shaped as a lotus leaf. CR fused with Hp and represented with two setae.

Female. Carapace (Fig. 13A). Slightly larger than males. L ~ 382 µm, H ~ 211 µm . Shape and all other morphological features similar to male.

GF (Fig. 5E). Basal part rectangular. CR setae not observed. Ovary sub-rectangular.

All other appendages same as in male.