Hemicytherura kajiyamai Hanai, 1957

Yoo, Hyunsu, Tanaka, Hayato, Tsukagoshi, Akira, Lee, Wonchoel & Karanovic, Ivana, 2019, Cytheroid ostracods (Crustacea) from South Korea, with description of a new species, Zoosystema 41 (22), pp. 419-441 : 423-429

Hemicytherura kajiyamai Hanai, 1957

( Figs 4-8 )

Hemicytherura kajiyamai Hanai, 1957: 24 , pl. 2, figs 1 (a-d). — Okubo 1980: 15, fig. 5. — Ikeya et al. 1985, pl. 5, figs 12, 13, 16. — Ishizaki & Matoba 1985: pl. 4, fig. 8. — Ruan & Hao 1988: 293, pl. 50, fig. 15. — Kamiya 1989: 85, fig. 13 (4). — Ikeya & Suzuki 1992: 128, pl. 5, fig. 3. — Kamiya et al. 2001: fig. 13 (5), fig. 17 (7). — Nakao et al. 2001: fig. 5 (7). — Yamaguchi 2003: 135, fig. 1(g). — Tanaka et al. 2011: 23-25, fig. 1(a-b), 2(a), 3(a), 4(a), 5. — Schornikov & Zenina 2014: 225 pl. VIII (no.7-8).

Cytheropteron videns – Kajiyama 1913: 4 , 5, pl. 1, figs 19-25.

TYPE LOCALITY. — The shore from behind of an Imperial villa, Hayamamachi, Kanagawa Prefecture (beach sand), Japan .

MATERIAL EXAMINED. — South Korea. 4 ♀, intertidal-zone algae at Hujeong Beach, Hujeong 2-gil, Jukbyeon-myeon, Uljin-gun , Gyeongsangbuk-do., 37°04’12.3”N, 129°25’01.0”E, 0.1 m depth., dissected on four each slides, NIBRIV0000753777 , NIBRIV0000834100 , NIBRIV0000834101 , NIBRIV0000834102 , valves on the micropaleontological slides, NIBRIV0000753777 , NIBRIV0000834100 , NIBRIV0000834101 , NIBRIV0000834102 . — 2♂, same locality, dissected on two slides, NIBRIV0000834103 , NIBRIV0000834104 , valves on the micropaleontological slides, NIBRIV0000834103 , NIBRIV0000834104 . — 6 specimens kept in 2 ml vial in 99% ethanol, NIBRIV0000834105 , 5 specimens kept in 2 ml vial in 99% ethanol, MNHN .

DESCRIPTION OF FEMALE

Carapace ( Figs 4 A-D; 5A; 6A, B)

Relatively small in size, L max = 332 Μm, min = 325 Μm, average c. 329 Μm; H max = 198 Μm, min = 190 Μm, average approximately 193,5 Μm, N = 4. Slightly asymmetrical, LV slightly larger than LV, RV hanging over dorsal margin of LV. Dorsal margin highly arched with greatest H in the middle of L, ventral margin almost straight, with setae and thin selvage. Posterior end long and with narrow extension, antero-ventral margin with four crenulations. Valve ornamented consisting of 12 fossae, positioned actiniform started from central part, fossae with thin ridges and setae ( Fig. 5A ). Muscular scar imprints consisting of a row of four vertical scars and one frontal scar present ( Fig. 6E ). Only normal pores present. Hinge lophodont ( Fig. 4E ).

Antennule ( Fig. 6F )

Six-segmented. First segment without setae. Second segment with one bare seta situated postero-medially reaching one-third of fourth segment. Third and fourth segments each with one bare seta antero-distally; seta on third segment reaching end of fourth segment and seta on fourth segment reaching half of terminal segment. Fifth segment with two setae antero-distally: one seta more than 2 times longer than terminal segment; other seta 1.5 times longer than same segment. Same segment also with one posterodistal seta 2 times longer than terminal segment. Sixth segment with two short setae distally, one of which 2 times longer than terminal segment and other 2.5 times longer than same segment. Length ratios between six segments: 3: 3.2: 2.5: 2.8: 2.8: 1.

Antenna ( Fig. 6H )

Five-segmented. Exopod transformed into three-segmented spinneret seta. First endopodal segment without setae. Second segment with one bare and one plumose seta situated postero-distally; bare seta reaching half of third segment and plumose seta reaching two-third of the same segment. Third segment with two plumose setae postero-distally reaching half of fourth segment, and several setulae antero-proximally. Fourth segment with one bare seta situated medially reaching half L of the fourth segment; one plumose seta posteromedially not reaching distal margin of the fourth segment, and one short plumose seta antero-distally.Terminal segment with two strong, serrated claws and one short seta situated between claws. Appendage with several stiff seatulae groups along posterior margin of the first endopodal segment and on the anterior margin of the second endopodal segment. Length ratios between four segments: 1.9: 1.2: 1: 2.1.

Mandibule ( Fig. 6G )

Coxa with one row of setula on distal margin, and with one seta. Palp 3 segmented. First segment with one bare seta antero-medially, and three bare setae on antero distal margin. Second segment with four setae postero-distally, and two setae antero-distally, all bare. Terminal segment with three setae on distal margin. Setae on all segments very strong, almost claw-like. Length ratio between three segments: 5.5: 1.5: 1.

Maxillule ( Fig. 7D )

Palp present and 2-segmented. First segment with four bare setae on distal margin. Second segment with two bare setae on distal margin. Masticatory organ with three endites. First endite with four bare setae on distal margin. Second endite with four bare setae on distal margin. Third endite with two bare setae on distal margin. Exopodite with 12 plumose and two bare setae (“aberrant” setae) in vibratory plate.

Leg 5 ( Fig. 7A )

Four-segmented. First segment with one plumose seta anteromedially reaching distal end of the same segment, two plumose setae on antero-distal margin reaching half L of the second segment, one plumose and one bare seta on posterior margin not reaching end of the first segment. Second segment with one plumose seta antero-distally not reaching end of the third segment; row of setulae present medially along anterior to distal margin. Third segment with one row of setulae medially along anterior to distal margin. Terminal segment with setulae medially along anterior to distal margin, and most distally with one claw. Length ratio between four segments: 2.7: 1.4: 1: 1.2.

Leg 6 ( Fig. 7B )

Four-segmented. First segment with one plumose and one bare seta situated antero-medially reaching end of the first segment; one bare seta antero-distally reaching one-third of second segment, one plumose seta postero-medially reaching one-third of the same segment and setulae on distal margin. Second segment with one bare seta antero-distal margin reaching 3/4 of the third segment. Third segment without seta and setulae. Terminal segment with one claw on distal margin. Length ratios between four segments: 2.3: 1.7: 1: 1.2.

Leg 7 ( Fig. 7C )

Four-segmented. First segment with one plumose seta anterodistally reaching 1⁄5 of the second segment. Second segment with one plumose seta antero-distally reaching 1/4 of terminal segment, setulae present along anterior margin. Third segment with setulae along anterior margin to distal margin.Terminal segment with setulae along antero-medial and distal margins, claw present on distal margin. Length ratios between four segments: 2.3: 2.3: 1: 1.3.

Genital field ( Fig. 7E )

Ellipsoidal. Setulae positioned on distal margin. Two bare setae positioned on antero-distal margin.

DESCRIPTION OF MALE

Antennule, antenna, mandibular, maxilular same as in female.

Carapace ( Fig. 4C, D ; 5B )

Smaller than female, L max = 309 Μm, L min = 303 Μm, L average = 306 Μm; H max = 172 Μm, H min = 168 Μm, H average = 170 Μm, N = 2 specimens .. Ornamentation slightly different than in female, i.e., fossa no. 8 in male divided into two parts ( Fig. 4C arrow and 5B).

Leg 5 ( Fig. 8A )

Four-segmented. First segment with one plumose seta antero-proximally reaching end of the first segment, two plumose setae antero-distally reaching half of the second segment; one plumose and one bare seta on posterior margin not reaching end of the first segment. Second segment with one plumose seta antero-distally not reaching end of the third segment; setulae present medially along anterior margin. Third segment with setulae situated medially along anterior and distal margins. Terminal segment with setulae antero-medially and one claw on distal margin. Length ratios between four segments: 2.1: 1.5: 1: 1.

Leg 6 ( Fig. 8B )

Four-segmented. First segment with two plumose setae antero-medially reaching slightly beyond the first segment, one plumose seta antero-distally reaching one-third of the second segment; one bare and one plumose seta posteroproximally reaching end of the first segment. Second segment with one plumose seta antero-distally reaching half of terminal segment, setulae present along antero-medial and distal margins. Third segment with setulae along anterior margin. Terminal segment with setulae along anterior margin, one strong claw on distal margin. Length ratios between four segments: 2.3: 1.7: 1: 1.3.

Leg 7 ( Fig. 8C )

Four-segmented. First segment with one plumose seta anterodistally reaching 1⁄6 of the second segment, one bare seta postero-distally also reaching 1⁄6 of the same segment. Second segment with one plumose seta antero-distally reaching one-third of terminal segment; setulae present along anteromedial and distal margins. Third segment with setulae on antero-medial and distal margins. Terminal segment with claw on distal margin, setulae present on antero-medial and distal margins. Length ratios between four segments: 1.9: 2.1: 1: 1.3.

Brushed organ ( Fig. 8D )

With more than 15 setae on distal margin. Positioned behind L7 and below hemipenis.

Hemipenis ( Fig. 8E, F )

Distal lobe subdivided into two rectangular parts: dorsal with almost straight distal margin and ventral with v-shaped distal margin. Dorsal part with folded and one distally pointed extension. Reduced caudal rami on ventral margin. Copulatory duct very simple.

Figures

FIG. 4. — Hemicytherura kajiyamai Hanai, 1957 SEM photographs;female NIBRIV0000753777:A, RV external view;B, LV external view;male NIBRIV0000834103; C, RV external view; D, LV external view;E, hingement (lophodont); F, muscular scar; G, posterior ventral margin; H, seta pore type; no. 8 fossa divided in 3 parts on female RV (A) and in 2 parts on male RV (C). Abbreviations: see Material and methods. Scale bars: A-E, 100 μm; F, 20 μm; G, 50 μm; H, 10 μm.

FIG. 5. — Hemicytherura kajiyamai Hanai, 1957: A, female NIBRIV0000753777: RV external view; B, male NIBRIV0000834103), RV external view; no. 8 fossa divided in 3 parts on female RV (A) and in 2 parts on male RV (B). Abbreviations: see Material and methods. Scale bar: 50 μm.

FIG. 6. — Hemicytherura kajiyamai Hanai, 1957: A, B, E-H, female NIBRIV0000753777: LV internal view (A), RV internal view (B), muscular scar (right valve) (E), A1 (F), Md (G); A2 (H); C, D, male NIBRIV0000834103: LV internal view (C); RV internal view (D). Abbreviations: see Material and methods. Scale bars: 50 μm.

FIG. 7. — Hemicytherura kajiyamai Hanai, 1957, female NIBRIV0000753777: A, L5; B, L6; C, L7; D, Mxlr; E, GF. Abbreviations: see Material and methods. Scale bar: 50 μm.

FIG. 8. — Hemicytherura kajiyamai Hanai,1957,male NIBRIV0000834103:A, L5;B, L6; C, L7; D, BO;E, heft Hp, ventral view;F, lobe of Hemipenis,NIBRIV0000834104 (2nd male right Hp, ventral view), *, reduced caudal rami. Abbreviations: see Material and methods. Scale bars: 50 μm.