Paradoxostoma koreana, Lee & Yoo & Kim, 2017

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, One new species and three records of cytheroid ostracods (Crustacea, Ostracoda) from Korea, Journal of Species Research 6, pp. 38-50 : 39-42

Paradoxostoma koreana sp. nov. ( Figs. 1-3)

Material Examined. Holotype: male, dissected on one slide ( NIBRIV0000753786 ) and shell on SEM slide; allotype, female dissected on one slide ( NIBR IV0000811369 ), shell on micropaleontological slide ; Paratypes: one male and one female dissected ( NIBR IV0000811370 , NIBRIV0000811371 ), shells on micropaleontological slides .

Type locality: Gajin beach, Goseong-gun, Gangwon-do, Korea. 38°32 ʹ 37.2 ʺ N, 128°24 ʹ 20.9 ʺ E, 05 Oct. 2015, collected by Akira Tsukagoshi, Hayato Tanaka and Hyunsu Yoo.

Description. Male: Carapace rhomboidal in lateral view ( Fig. 1 A-C). Dorsal margin highly arched, pointed at the place of the greatest height which is situated slightly behind the middle. From the point of greatest height dorsal margin slopping towards both anterior and posterior ends. Anterior margin narrow. Posterior margin with prominent caudal process, below which posterior margin inclined towards ventral margin. Ventral margin almost straight. RV considerably higher than LV. Surface of the shell smooth and covered with only few sensilla. Inner calcified lamella wider anteriorly than posteriorly. Line of concrescence relatively wide with few canals, which are fused on the anterior end and separated on the posterior. L including caudal process) equaling 0.48 mm, greatest H of the RV = 55% of total L, and on the LV = 50%

A1 ( Fig. 2A) 6-segmented, slender. First and second segments bare, third segment with one antero-distal short seta and with posterior margin covered with setulae; fourth segment with one seta distally on each side of the segment, posterior one being longer; penultimate segment distally also with one short seta; terminal segment with three short setae. L ratios between six segments 6.7: 5.4: 4.4: 5.8: 3: 1.

A2 ( Fig. 2B, C) 5-segmented with penultimate segment distinctively subdivided. Spinneret seta long and 3-segmened. Protopodite bare. First endopodal segment with one long seta (reaching distal margin of the following segment) and with a one bunch of setulae; second endopodal segment also with one seta (not reaching distal end of the following segment); penultimate segment with one short distal seta; terminal segment with two claws, one strong and the other 1/3 of its L; both claws armed with small spines. L ratios between endopodal segments: 3.9: 5.5: 5: 1.

Md ( Fig. 2F) with stiliform coxa caring one seta. Exopodite with only one seta in the vibratory plate; endopodite slender with 4 segments. Setae observed only on the penultimate and terminal segments.

Mxl ( Fig. 2D) with two aberrant setae on the vibratory plate. Small palp present, consisting of small lobe and two naked setae. Masticatory process with two endites, each with four and five naked setae.

L5 ( Fig. 2H) 4-segmented. First segment with one dorsal seta situated proximally and one strong, claw-like seta situated distally. Second segment with one seta not reaching distal margin of the following segment; third segment bare, terminal segment caring a short claws armed with fine, long spines. L ratios between three distal segments 1.5: 1: 1.1.

L6 ( Fig. 2I) 4-segmented. Fist segment with one short dorsal seta situated proximally and one fine seta situated distally. Second segment with one short seta, not reaching middle L of the following segment; third segment bare and terminal segment with one short claw armed with fine, long spines. L ratios between the last three segments 1.9: 1: 1: 1.

L7 ( Fig. 2J) 4-segmented. First segment with only one short distal seta. Second segment with one short seta (not reaching half L of the following segment); third segment bare except of the bunch of setulae on distal margin; terminal segment with one short claw covered with fine, long spines.

Hemipenis ( Fig. 3A) with relatively narrow basal part with three flame-shaped processes: anterior distally with long projecting needle-like extension; medial tube shaped and posterior elongated bean-shaped with terminating with fine spine.

Female: Few dimorphism in neither shell shape and structure ( Fig. 1D, E) nor in soft parts morphology. Caudal process long ( Fig. 3B) and one genital lobe associat- ed with two setae (UR), other bare.