Loxoconcha tosaensis Ishizaki, 1968

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 : 119-120

3. Loxoconcha tosaensis Ishizaki, 1968 ( Figs. 3-5 )

Synonymy

Loxoconcha tosaensis sp. nov. ­ Ishizaki (1968): p. 31, Pl. 2, Fig. 3 ; Pl. 7, Figs. 6 ­9.

Loxoconcha tosaensis Ishizaki ­ Ishizaki (1971): p. 87, Pl. 3, Fig. 18; Tohru et al. (2005): Fig. 1G ; Yasuhara and Seto (2006): Fig. 4m .

Material examined. One male dissected on slide ( NIBR IV0000813449), shell of on micropalaeontology slide ( NIBRIV 0000813449).

Locality in Korea. Jeollanam­do, Goheung­gun, littoral close to Naro Space Center , 34°27.348 ʹ N 127°31.216 ʹ E, 18/08/2013, coll. I. Karanovic.

Identifier. Ivana Karanovic.

Diagnosis (male only). Small ostracod, less than 1 mm long ( Fig. 3A, B ). In lateral view, carapace oblong, slightly depressed antero­dorsally. Dorsal margin straight. Ventral margin straight to slightly convex around mouth region. Anterior margin broadly rounded. Posterior margin closes down on dorsal margin with angle; but no prominent caudal process. Surface ornamented with relatively regular coarse reticulation throughout. Eye tubercle distinct. Hinge of Loxoconcha type (gongylodont). Antennula 5­segmented with slender segments. Antenna 4­segmented: first segment carrying only spinneret seta (exopod), second segment with one postero­distally reaching middle of the following segment. Penulitmate segment with two setae situated anteriorly on one third of segment’s length, and three setae postero­medially, slightly below external setae, penultimate segment also carrying two short setae postero­distally; terminal segment with two claws ( Fig. 5B ). Mandibula ( Fig. 4A ) with two claws and two setae on terminal segment. Mandibular exopod with three setae. Vibratory plate of maxillula with 15 rays; maxillular palp 2-segmented, first segment carrying three setae; terminal segment elongated and with four setae. All maxillular endites with four setae, and third one in addition with one very thick seta situated proximally. Hemipenis ( Fig. 5A ) with triangular distal part and one additional lateral projection being very similar in shape like distal part; clasping organ withheld internally and in rod­like shape.

Distribution. Species has been reported from Japan, and it was known only from its shell. This is the first report of soft parts.

Remarks. This is the first description of the soft parts of L. tosaensis . It belongs to the uranouchiensis ­species group ( Tanaka and Ikeya, 2002).

Figures

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

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

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

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

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