Violacytherois sargassicola (Hiruta, 1976)

Yoo, Hyunsu, Thi, Van Anh Le & Karanovic, Ivana, 2020, Two Paradoxostomatidae (Ostracoda) species from South Korea with a key to genera of the family, ZooKeys 943, pp. 21-39 : 21

Violacytherois sargassicola (Hiruta, 1976) Figures 4 , 5 , 6

Cytherois sargassicola Hiruta, 1976: 24, figs 1-3.

Violacytherois sargassicola (Hiruta): Schornikov, 1993: 181, figs 7, 8; pl II, figs 7-10.

Material examined.

Male, dissected on one slide (NIBRIV0000813440) and shell on micropalaeontological slide; Female, dissected on one slide and shell was broken; two males dissected on one slide each, shell broken; one female dissected on one slide, shell broken; one juvenile dissected on one slide; shell on micropalaeontological slide and 12 specimens kept in 2 ml vial in alcohol.

Locality.

South Korea, Gyeongsangnam-do, Goseong-gun, Donghae-myeon, Dongdong beach; 34°59.63'N, 128°26.02'E, 0.5 m depth; 04 Apr. 2012; collected by Tomislav Karanovic and Ivana Karanovic.

Description of female.

Carapace (Figs 4A , 5A ). L approximately 647 µm, H approximately 295 µm. Carapace ellipsoidal in lateral view (Figs 4A , 5A ). Dorsal margin arched, antero-dorsal margin slightly curved, ventral margin almost straight with weak curve point near the middle, the greatest H which is situated slightly behind the middle. Eye absent. LV overlapping RV on anterior and posterior margin, conversely RV overlapping LV on dorsal margin (Fig. 4D ). Surface of the carapace smooth with few simple setae. Pore canals sparse, straight and distributed along the margin (Fig. 5A ) not branched. Inner lamella wide at anterior margin and increasingly wider ventral, while almost the same with posteriorly. Muscular scar imprints consisting of a row of four vertical scars and one frontal scar present (Fig. 5A ). Hinge adont (Fig. 4C ).

A1 and A2 same as in male (see description below).

Md (Fig. 6F ). Coxa with five small teeth and one strong tooth on distal margin, one bare seta antero-medially not reaching end of the antero-distal margin. Palp with two-segmented endopodite and exopodite carrying one bare seta (broken). First endopodal segment without any seta, almost three times as long as second segment. Second segment with ten setae, one plumose and one bare seta on antero-distally, eight bare setae on distal margin.

Mxl (Fig. 6E ). Palp present with five bare setae on distal margin almost same length as the palp segment, setulae present along anterior to distal margin and posterior-proximally. Two long setae at the middle of vibratory plate (aberrant setae). Masticatory process with three endites, first and second endites each with four bare setae almost half length of palp segment, third endite with three bare setae almost 1/3 length of palp segment.

L5 (Fig. 6A ). Four-segmented. First segment with one plumose seta antero-medially not reaching end of the same segment, one claw-like seta on antero-distal margin. Second segment with setulae along anterior to distal margin, one bare seta antero-distally, reaching 1/5 of terminal segment. Third segment with setule along anterior to distal margin. Terminal segment with claw on distal margin. L ratio between four segments 4: 1.6: 1: 1.1.

L6 (Fig. 6B ). Four-segmented. First segment with one plumose seta antero-medially, not reaching end of the same segment, one plumose seta antero-distally reaching 1/3 of second segment. Second segment with setulae along anterior to distal margin, one bare seta antero-distally, reaching 1/4 of terminal segment. Third segment with setulae along anterior to distal margin. Terminal segment with claw-like seta on distal margin. L ratio between four segments 2.9: 1.7: 1: 1.08.

L7 (Fig. 6D ). Four-segmented. First segment with one plumose seta antero-distally reaching 1/7 of the second segment. Second segment with setulae along anterior to distal margin, one plumose seta antero-distally reaching end of third segment. Third segment with setulae along anterior to distal margin. Terminal segment with one claw like seta on distal margin. L ratio between four segments 2.8: 2.6: 1: 1.36.

GF (Fig. 6C ). Basal part subtriangular. Ovary kidney-bean shaped, situated at the middle of the basal capsule. One caudal ramus seta present. One end of the body seta present.

Description of male.

A1 (Fig. 5C ). Six-segmented. Fourth and penultimate segment fused. First segment without any seta. Second segment with setulae postero-medially and along anterior to distal margin. Third segment with setulae antero-proximally, one bare seta antero-distally, reaching end of fourth segment. Fourth segment with two bare setae antero-distally, one reaching end of terminal segment, another reaching half of same segment, one bare seta postero-distally, reaching end of terminal segment. Fifth segment with two bare setae antero-distally almost twice as long as terminal segment. Terminal segment with three bare setae on distal margin almost 2.5 times as long as same segment. L ratio between five segments 3.25: 6.5: 2.25: 2.42 (fused segment): 1.

A2 (Fig. 5B ). Five-segmented. Exopod transformed into three-segmented spinneret seta. First segment without any seta. Second segment with two setae postero-distally, one plumose seta reaching slightly over half of terminal segment. Third segment with one bare seta postero-distally not reaching half of the terminal segment, two bare setae situated medio-distally, not reaching half of the terminal segment. Fourth segment with setulae along antero-distal margin; one bare seta on posterior-distal margin, reaching slightly over distal end of the same segment; one bare seta antero-medially, not reaching distal end of the same segment. Terminal segment with one claw and one short seta fused with it. L ratio between three segments (excluding terminal segment) 2.5: 1.1: 1: 1.3.

Hp (Fig. 5D ). Basal part subrectangular form with two bare setae on anterior medially. Distal lobe subtriangular with slightly cuneiform distal tip. Same lobe also vertically subdivided.

Other appendages same as in female.

Figures

Figure 4. SEM photographs of Violacytherois sargassicola (Hiruta, 1976) A, D female B, C male: A RV external view B LV external view C RV internal view with soft parts D dorsal view.

Figure 5. Violacytherois sargassicola (Hiruta, 1976) A female B-D male: A RV internal view B A 2 C A 1 D Hp. All scale bars: 100 µm.

Figure 6. Violacytherois sargassicola (Hiruta, 1976): Female A L 5 B L 6 C GF D L 7 E Mxl F Md. All scale bars: 100 µm.