Glacioloxoconcha jeongokensis, Yoo & Huyen & Chae & Karanovic, 2023

Yoo, Hyunsu, Huyen, Pham Thi Minh, Chae, Jinho & Karanovic, Ivana, 2023, Three Loxocaudinae species (Ostracoda, Podocopida) from South Korea, ZooKeys 1138, pp. 183-209 : 183

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.

Figures

Figure 4. Glacioloxoconcha jeongokensis sp. nov.: male (NIBRIV 0000882303, NIBRIV 0000882313 holotype) A LV internal view B A 1 C A 2 D endopodite of Mxl E vibratory organ F Md G BO. Scale bars: 50 µm (B-F); 100 µm (A).

Figure 5. Glacioloxoconcha jeongokensis sp. nov.: male (NIBRIV 0000882303 holotype) A L 5 B L 6 C L 7 D Hp; female (NIBRIV 0000882309 allotype) E GF. Scale bar: 50 µm.

Figure 6. SEM photographs of Glacioloxoconcha jeongokensis sp. nov.: male (NIBRIV 0000882313 holotype) A LV external view B Simple seta pore on external carapace; male (paratype) C dorsal view D posterior part of dorsal margin E ventral view F postero-ventral part of ventral margin.

Figure 13. Internal view of female carapace A Glacioloxoconcha jeongokensis sp. nov. (NIBRIV 0000882311 allotype) B Loxocauda cf. orientalis (NIBRIV 0000882312) C Loxocauda orientalis Schornikov, 2011 (MABIKCR 0025820).