Callistocythere laevis Okubo, 1979

Ji, Su-Jung, Jung, Chuleui, Bang, Hyun Woo, Song, Min Ok, Jung, Jongwoo, Yoon, Seong Myeong, Lee, Seunghwan, Keum, Seoyoung, Yang, Hee-Min, Lee, Dongmin, Lee, Geon Hyeok, Oh, Jaeseok, Kim, Kichoon, Park, Hansol, Moon, Heejin, Joharchi, Omid, Kang, Yeseul, Eom, Keeseon S., Lee, Kyung Jin, Eun, Ye, Kim, Taeho, Karanovic, Ivana, Lee, Jeounghee, Choe, Seongjun & Min, Gi-Sik, 2023, Unrecorded species of Korean invertebrates discovered through the project of ‘ Discovery of Korean Indigenous Species’ II, Journal of Species Research 12 (1), pp. 68-89 : 84

34. Callistocythere laevis Okubo, 1979 ( Fig. 34 )

ȁŏŅPḄḤṆḇNj (ṵAE)

Material examined. Boseong-gun (34°40.172′N, 127° 05.424′E), Korea; collected by I Karanovic on 17 August 2013.

Deposition. NIBRIV0000835138.

World distribution. Japan and Korea.

Diagnosis. Size about 1.2 mm. Shell thick (strongly calcified) and laterally compressed. Surface smooth. Dorsal margin slightly arched, anterior margin obliquely rounded, posterior margin narrower than anterior. Ventral margin distinctly sinuated. Radial pore canals poly-furcated anteriorly and posteriorly. Hingement on right valve composed of anterior and posterior teeth and intermediate shelf, which is finely pitted throughout and has one socket anteriorly. On the left valve hingment composed of anterior and posterior sockets and intermediate ridge, crenulated throughout and with one prominent tooth anteriorly. Hemipenis with anterior process of small triangular lamella; middle and posterior processes of flame-shaped lamellae curved backwards. Copulatory tube spiral, coiling several times.

Remarks. This species has an intermediate position between Callistocythere and Leptocythere . Like the latter genus it is elongated and with a smooth shell, but like the former genus it has poly-furcated radial pore canals.

Figures

Fig. 34. Callistocythere laevis Okubo, 1979. A. left valve; B. right valve; C. hemipenis.