Ekpontocypris koreana, Karanovic, 2020

Karanovic, Ivana, 2020, Two new Pontocyprididae (Ostracoda) species from Korea, Journal of Natural History (J. Nat. Hist.) 53 (45 - 46), pp. 2801-2815 : 2803-2807

Ekpontocypris koreana sp. nov. ( Figures 1 – 3 )

http://www.zoobank.org/ urn:lsid:zoobank.org:act:1B3664EA-4999-4625-81A3-9BE31D11F517

Holotype. Male, dissected on one slide, shell on micropaleontological slide ( NIBR IV0000813447 )

Type locality. South Korea, Yulpo Beach , interstitial (large gravel beach), 18/08/2013, collectors Ivana and Tom Karanovic; 34°24.994 ʹ N 127°29.212 ʹ E .

Other material. Male , dissected on one slide, shell broken, from South Korea, Bangjukpo Beach, intertidal zone, 19/08/2013, collectors Ivana and Tom Karanovic; 34°37.826 ʹ N 127° 47.574 ʹ E .

Female , dissected on one slide, shell kept in a drop of CMC-10 medium (on the same slide as the soft parts), from South Korea, Gupyeong-ri, intertidal zone, 30/03/2013, collectors Tom and Ivana Karanovic, 35°, 57.351 ʹ N, 129°32.799 ʹ E .

Etymology. The species is named after Korea.

Description

Male. Length around 0.9 mm. Greatest height situated at the mid-length, equalling 53% of the length ( Figure 1 (a,b)). Dorsal margin highly arched and sloping towards anterior and posterior margins. Posterior margin narrow, but not pointed. Anterior margin rounded. Ventral margin slightly concave around the mouth region. Muscle scar region consisting of five large, rounded scars, arranged in a typical pontocyprinid pattern. Line of concrescence narrow, but much more on the posterior end ( Figure 1 (c,d)). Marginal pore canals short and not branching. There is a group of pimple-like structures bellow the point of the greatest height ( Figure 1 (e)). Surface densely covered with sensilla, some cylindrical originating from lip-like pores, and other with bulbous distal end and originating from simple pores ( Figure 1 (f)).

A1 ( Figure 2 (a)) eight-segmented, but the suture between the first and second segment not clearly visible. First segment with one anterior seta not reaching distal end of the second segment. Second segment with one long and one shorter posterior seta (shorter seat situated postero-distally); same segment with one seta reaching distal end of the following segment. Third and fourth segments with one antero-distal and one postero-distal seta each. Fifth and sixth segments with two long anterior setae and one short posterior seta. Seventh segment with a total of five setae, and terminal segment with two long setae and one seta transformed into a sensory organ (ya seta). Terminal segment very small, barely visible.

A2 ( Figure 2 (b)) five-segmented. Exopod reduced to a plate with one long and one short seta. Swimming setae relatively long and reaching middle of the terminal claws. Male sensory setae simple and situated postero-distally on the second endopodal segment. Penultimate segment with three claws and one seta. Only one claw observed on the terminal segment.

Md-palp four-segmented ( Figure 3 (e)). First segment with four setae, of which two are fused in proximally. Second segment internally with five setae, and externally with two setae. Penultimate segment with three external, two medial, and three internal setae; in addition one claw present on the same segment internally. End segment with four claws.

Mxl-palp ( Figure 3 (g)) two-segmented. First segment with five setae (one situated proximally, four distally on the segment). Second segment with three claws and three tiny setae.

Prehensile palps ( Figure 2 (d,e,h,i)). Body robust and fingers with right-angled hooks. Finger of the right palp with lump. Pegs on both palps subtriangular and blunt. On right palp pegs associated with two fine setae (one long and one short), on the left palp the short seta not visible.

L6 ( Figure 3 (h)) six-segmented. Two first segments (protopod) carrying four short setae. All setae on the endopodal segments short. All, except the terminal segment, carry only one seta. Terminal segment with two tiny setae and a long, distally gently curved claw.

L7 ( Figure 3 (f)) five-segmented. Third segment with one thick seta not reaching end of the penultimate segment; same segment with a tuft of strong setae, which are marginal extensions of the segment. Penultimate segment with one short seta and with scale-like projections laterally. Terminal segment very small and with chelate seta armed with distinct spines decreasing in length. Two additional setae present on the same segment: one as long as chelate seta, the other 1.5 times longer.

CR ( Figure 2 (f)) with stout shaft. Anterior seta half as long as anterior claw. Anterior claw half as long as posterior claw. More distal posterior seta very strong and as long as posterior claw. Two more proximal setae thinner, subequally long and 1.5 times longer than posterior claw.

Hemipenis ( Figure 2 (c)) distally broad with rounded outer part, and with a distinct hook-like projection close to the middle.

Ejaculatory tube ( Figure 2 (g)) embedded in a strongly chitinized structure with opposing ‘ Z ’ shaped extensions both proximally and distally.

Female with slightly less arched dorsal margin ( Figure 3 (a)). A2 ( Figure 3 (c)) on the penultimate segment carrying two long and one half as long claw. L6 ( Figure 3 (b)) with three-segmented endopod. Penultimate segment with one seta, terminal segment with two short setae and a claw. Basis with a tuft of five setae and with two additional setae situated more distally. Anterior seta on the CR ( Figure 3 (d)) longer than in male. All other appendages are similar to male.

Key to living representatives of the genus Ekpontocypris

1. Zone of concrescence wide, with long marginal pore canals, ventral margin strongly concave.. ................................................................................................... E. epicyrta ( Maddocks, 1969)

– Zone of concrescence narrow, marginal pore canals short, ventral margin almost straight.. .......................................................................................................................................................... 2

2. Hook (finger) of the right prehensile palp with a lump slightly below the middle.. ....... ............................................................................................................................................................. E. koreana

– Hook (finger) of the right prehensile palp without a lump, finger straight.. .................. 3

3. Hemipenis distally without any protruding hook-like processes.. .......................................... .................................................................... E. pirifera ( Müller, 1894) and E. japonica ( Okubo, 1979)

– Hemipenis distally with protruding hook-like processes.. ...................................................... 4

4. Two proximal setae on the posterior margin of the CR subequally long.. .......................... ....................................................................................................................... E. litoricola ( Maddocks, 1969) – One of the proximal setae on the posterior margin of the CR more than 2 times shorter than the other.. ........................................ ....................................... E. iquiquensis ( Hartmann, 1962)

Figures

Figure 1. SEM of Ekpontocypris koreana sp. nov. Male; (a) LV, external view; (b) LV, internal view; (c) anterior margin of the LV, internal view; (d) posterior margin of the LV, internal view; (e) dorsal margin of the LV, internal view; (f) detail of the carapace surface.

Figure 2. Line drawings of Ekpontocypris koreana sp. nov. Male; (a) A1; (b) A2; (c) hemipenis; (d) right prehensile palp; (e) left prehensile palp; (f) CR; (g) ejaculatory tube; (h) right prehensile palp; (i) left prehensile palp. Scales 0.1 mm.

Figure 3. Line drawings Ekpontocypris koreana sp. nov. (a–d) female; (e–g) male. (a) RV, internal view; (b) L5; (c) A2; (d) CR; (e) Md palp; (f) three terminal segments of L7; (g) Mxl palp; (h) L6. Scales 0.1 mm.