Loxocorniculum mutsuense Ishizaki, 1971

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 : 120

4. Loxocorniculum mutsuense Ishizaki, 1971 ( Fig. 6 )

Synonymy

Loxocorniculum mutsuensis sp. nov. ­ Ishizaki (1971): p. 89, Pl. 5, Fig. 11, Pl. 6, Figs. 3 , 6 , 7 , Pl. 7, Fig. 5 .

Loxocorniculum mutsuense Ishizaki ­ Hanai et al. (1977): p. 65; Okubo (1980): p. 424, Figs. 17, 20; Tohru et al. (2005): Fig. 1Q .

Material examined. One male dissected on slide ( NIBR IV0000831180), shell of on micropalaeontology slide ( NIBRIV 0000831180).

Locality in Korea. Jeollanam­do, Boseong­gun , interstitial, 34°40.172 ʹ N 127°05.424 ʹ E, 17/08/2013, coll. I. Karanovic.

Identifier. Ivana Karanovic.

Diagnosis. Small ostracod, less than 1 mm long ( Fig. 6A, B ). Carapace sexually dimorphic, males more elongated. Left and right valve similar. Trapezoidal in lateral views, greatest height situated anteriorly. Dorsal margin straight. Anterior margin broadly and obliquely rounded, forming cardinal angle with dorsal margin. Posterior margin narrowly rounded, slightly projecting toward postero­dorsal area. Ventral margin slightly sinuated. Surface pitted. Five ridges on surface: two anterior and three posterior; postero­dorsal one terminating in horn­like protuberance. Eye tubercle prominent. Hinge of Loxoconcha type (gongylodont). Antennula 5­segmented with ancestral segments four and five fused ( Fig. 6C ). Antenna 4­segmented with two distal claws ( Fig. 6D ). Hemipenis subtriangular, anterior process narrowly triangular and with one clearly visible strongly sclerified copulatory process, in shape of upward turned hook ( Fig. 6D ).

Distribution. Species has been reported from Japan ( Okubo, 1980), Russia ( Schornikov, 2006). This is the first record for Korea.

Figures

Fig. 6. Loxocorniculum mutsuense Ishizaki, 1971. Male.A, Left valve; B, Right valve; C, Antennule; D, Antenna; E, Copulatory organ.

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

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

Fig. 1. Loxoconcha bizenensis Okubo, 1980. Male. A, Left valve; B, Antennule and Antenna; C, Antenna (High maginification); D, Male copulatory organ.