Sclerochilus (Praesclerochilus) jejuensis, Le & Karanovic, 2021

Le, Van Anh Thi & Karanovic, Hyunsu Yoo and Ivana, 2021, One new Sclerochilus (Praesclerochilus) Sars (Ostracoda) species from Korea, Journal of Species Research 10 (3), pp. 255-261 : 256-260

Sclerochilus (P.) jejuensis sp. nov.

Holotype. Male, dissected on one slide kept in a drop of CMC-10 medium ( NIBRV0000862858 ), and shell on micropalaeontological slide; paratypes: two males, dissected on one slide each.

Etymology. The name derives from Jeju Island ( South Korea) from where the material was collected. It is an adjective in genitive singular (masculinum).

Type locality. South Korea, Jeju-si , Jocheon-eup, Hamdeok-ri; 33°32′36.38″N, 126°40′11.48″E, littoral zone; 27-28 Nov. 2011, collected by Ivana Karanovic.

Description. Male. Carapace ( Figs. 1 , 2A ). LV oblongly reniform in lateral view. Length around 0.9 mm, greatest height considerably behind the middle. Dorsal margin highly arched and sloping towards to anterior and posterior margins. Both margins rounded, with a number of normal pore canals scattered along posterior to anterior. Inner lamella widened anteriorly and narrowed ventrally and posteriorly. Five muscle scars organized in a vertical row but forth muscular scar is divided into two parts.

A1. ( Fig. 2B ). Seven-segmented. Length ratio between seven distal segments: 4.7: 2.7: 2.9: 3.1: 2.5: 1: 3.2, along anterior margin. First segment without setae and setula. Second segment with one bare seta situated antero-medially not reaching distal end of next segment and one seta postero-medially exceeding distal end of the fifth segment. Third segment with three setulae on postero-distally margin and one long posterior seta, reaching distal end of terminal segment. Fourth segment with one short anterior-distal seta and one long seta postero-distally, being four times longer than the terminal segment. Fifth segment with three long setae antero-distally and two long postero-distally setae. Sixth segment with one barely visible seta antero-distally. Terminal segment very thin, with two long bare setae distally. All setae bare.

A2. ( Fig. 2C ). Five-segmented. Length ratio between five distal segments: 1.4: 1.2: 2.5: 1.7: 1, along anterior margin. Exopodite forms a bare seta, sharply narrowed at the level of its middle length. First segment without setae and setula. Second segment with two setae, both pappose: one reaching distal margin of the following segment, the other twice as short. Third segment with two setulae on the anterior margin and two short setae on posterior distal edge: one robust (almost claw-like) and bare, the other thinner and with a few setulae along the margin. Penultimate segment with short setula along posterior margin and one short robust seta on posterior-distal margin. Fifth segment about half the length of fourth segment, narrowed in the middle, equipped with three claws: one comb-shaped and twice as short as the other two, sub-equally long, claws.

Md. ( Fig. 3A, 3B ) Plump palp with three segments; first segment with one long seta antero-distally reaching end of the distal claw, second segment with four slender setae situated antero-distally, third segment with one fine, short seta on anterior-distal edge, one slender seta and one strong plumose seta. Stout coxa narrowly produced with one slender seta medially reaching distal end of coxa and three teeth at lower distal end.

Mxl. ( Fig. 3C ). Palp one-segmented with one slender seta medially on the outer margin, two claws distally, and one juxtaposed setae on posterior margin.

L5. ( Fig. 3D ). Four-segmented. Length ratio between four distal segments: 3.8: 1.3: 1: 1.2, along anterior margin. First segment with two juxtaposed setae in which two of sub-equal lengths near posterior proximal edge, one of which is shorter and stronger than the others, also having a strong claw on antero-distal margin reaching end of the following segment. Second and third segments with only one bare anterior seta. Terminal segment with one apical claw including one setula on posterior margin and one spine-like setula antero-medially.

L6. ( Fig. 3E ). Four-segmented. Length ratio between four distal segments: 3.6: 1.9: 1: 1, along anterior margin. First segment with one bare seta on posterior margin not reaching end of this segment, two bare anterior setae dividing anterior margin into three sub-equal parts, and one bare seta on anterior-distal margin. Second segment with spines along anterior margin and one bare short seta antero-distally. Penultimate segment with one bare antero-distal, strong and one short postero-distally spine. Only one apical claw on terminal segment.

L7. ( Fig. 3F ). Four-segmented. Length ratio between four distal segments: 2.7: 2: 1.1: 1, along anterior margin. First segment with four bare setae, one on posterior medial margin, not reaching end of the first segment, and the remaining three setae dividing anterior margin into three sub-equal parts in length in which two setae situated antero-medially and one antero-distally. Second segment with setulae along both posterior and anterior margins, and one bare seta on antero-distally. Third segment with one seta antero-distally. Terminal segment with one setula on each side of the margin and one apical claw curving rectangularly carrying a spinulamedially on the posterior margin and one spine on the anterior margin.

Hp. ( Fig. 4A, 4B ). Hp strongly symmetrical. Basal section oval with three processes. Three lamelliform processes: two overlapping and occupying posterior margin and one situated medially and strongly asymmetrical on left and right hemipenis. The process on the anterior margin calabash shaped and with structures that resemble pore canals. Caudal ramus with elongated shaft reaching basis of the anterior process and strongly asymmetrical: on one hemipenis carrying three distal setae and three basal setae, and on the other carrying two distal and one basal seta.

Females not collected.

Figures

Fig. 1. Sclerochilusjejuensis (Sars, 1866): SEM photograph of LV (internal view) of the holotype male. Scale bar: 200μm.

Fig. 2. Sclerochilusjejuensis(Sars, 1866): Holotype, male.A, LV internal view; B, A1; C, A2. All scale bar: 100 μm.

Fig. 3. Sclerochilusjejuensis (Sars, 1866): Holotype, male. A, Md of holotype; B, Md of paratype; C, Mxl; D, L5; E, L6; F, L7. All scale bar: 100μm.

Fig. 4. Sclerochilusjejuensis(Sars, 1866): Holotype, male.A, Left Hp; B, Right Hp.All scale bar: 100 μm.