Pontocythere miurensis ( Hanai, 1959 ), 2019

Karanovic, Hyunsu Yoo and Ivana, 2019, Six species of the ostracod families Loxoconchidae and Cushmanideidae from South Korea, Journal of Species Research 8 (1), pp. 116-127 : 124-126

5. Pontocythere miurensis ( Hanai, 1959) ( Fig. 7 )

Synonymy

Cushmanidea miurensis sp. nov. ­ Hanai (1959): p. 299, Pl. 16, Figs. 7 ­10.

Cushmanidea miurensis Hanai ­ Hanai (1961): Fig. 4A .

Cushmanidea subjaponica Hanai ­ Okubo (1977): p. 135, Figs. 2 , 3 .

Pontocythere subjaponica Hanai ­ Kamiya and Nakagawa (1993): Pl. 1 Figs. 7 , 8 .

Pontocythere miurensis (Hanai) comb. nov. ­ Hanai et al. (1977): p. 25.

Pontocythere miurensis (Hanai) ­ Nakao and Tsukagoshi (2002): p. 76, Fig. 5 A­D.

Material examined. One female dissected on slide ( NIBR IV0000831179), shell of on micropalaeontology slide ( NIBRIV 0000831179).

Locality in Korea. Gyeongsangnam­do, Goseong­gun , littoral, 34°59.629 ʹ N 128°26.198 ʹ E, 31/03/2013, coll. I. Karanovic.

Identifier. Ivana Karanovic.

Diagnosis. Small ostracod, less than 1 mm long ( Fig. 7A, B ). Size about 1 mm. Carapace sub­quadrate in lateral view. Dorsal margin almost straight with one slight groove around middle length. Dorsal margin forming one angle with posterior margin and gently sloping towards anterior margin. Posterior margin almost straight with one caudal process at postero­ventral margin. Caudal process relatively small. Anterior margin more broadly rounded anteriorely than posteriorely. Ventral margin concave in middle. Greatest height situated behind middle. Surface ornamented with few irregular pits and weak ridges, especially in anterior part of shell. Hinge desmodont. Antennula 5­segmented, with relatively robust segments and short, stiff setae ( Fig. 7A ). Second antenna 4­segmented with two strong claws and one seta ( Fig. 7D ).

Distribution. Species has been reported from Japan ( Hanai et al., 1977), Russia ( Schornikov, 2006). This is the first record for Korea.

Remarks. There is confusion in the literature regarding the names L. miurensis and L. subjaponica ( Hanai, 1959) . Namely, Okubo (1977) reported P. subjaponica (in the paper referred to as Cushmanidea subjaponica ) and described the soft parts for the first time. However, Nakao and Tuskagoshi (2002) attributed Okubo’s (1977) finding to P. miurensis . The difference between the two species is a less developed caudal process in P. miurensis than in P. subjaponica , but this is very subtle. It is possible that P. miurensis and P. subjaponica are synonyms, but since the soft parts are known only for one of them, here we follow Nakao and Tsukagoshi (2002) ’s opinion and identified the Korean population as P. miurensis due to a slightly less developed caudal process than in P. subjaponica .

Figures

Fig. 7. Pontocythere miurensis (Hanai, 1959). Female. A, Left valve; B, Right valve; C, Antennule; D, Antenna; E, Copulatory organ.

Fig. 4. L. tosaensis Ishizaki, 1968. A, Mandibula; B, Maxillua; C, Vibratory organ; All scale bars are 50μm.

Fig. 2. Loxoconcha japonica Ishizaki, 1968. Female.A, Left valve; B, Right valve; C, Antennule; D, Antenna.

Fig. 3. Loxoconcha tosaensis Ishizaki, 1968.A, SEM photograph of Male left carapace; B, Right carapace.

Fig. 8. Pontocythere xiphoidea Nakao and Tsukagoshi, 2002. Male.A, Left valve; B, Right valve; C, Antennule; D, Antenna; E, Copulatory organ.

Fig. 5. L. tosaensis Ishizaki, 1968.A, Male copulatory organ; B, Antenna; Scale bar is 50μm.