• The Korean Journal of Zoology
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• v.36 no.1
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• pp.1-5
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• 1993

Two species and one subspecies of Trochidae collected from 13 localities in South Korea are described, all of which are newly known to Korea: Tristichotrochus condors multifiratu (Sowerby, 1875), Euchelus rubro fA. Adams, 1853) and Conotulopio (Awuiitrochus) mustelina (Gould, 1861). As a result, the Korean Trochidae comprises 26 species and 7 subspecies in 12 genera.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.244-245
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• 2000

The top shell, Omphalius rusticus (Gastropoda: Trochidae), is marine mollusk inhabiting underneath a rock in the intertidal zone of the coasts of Korea and Japan, and it is one of the edible gastropods. This species is a herbivorous animal. Up to now, there have been some reports on the Trochidae: aspects of classification, spawning periodicity, production, growth and size-frequency distribution of living populations, feeding, reproductive cycle, and induction of larval metamorphosis. (omitted)

• The Korean Journal of Malacology
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• v.24 no.2
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• pp.105-107
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• 2008

Two trochid shells of the genus Ginebis, G. crumpii(Pilsbry, 1893) and the genus Enida, E. japonica A. Adams, 1860, collected from the coast of Jeju Island in Korea are reported. Ginebis crumpii and Enida japonica are closely related to Calliostoma Swainson, but can be differentiated by the features of the aperture and umbilicus. These species are a new records to the Korean Molluscan fauna. At present, G. crumpii and E. japonica are the only species of the represented in Korean water. Including the new records in this study, the family Trichidae contains 30 genera and 57 species in Korean water.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.247-248
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• 2002

원시복족목 (Archaeogastropoda) 밤고둥과 (Trochidae)에 속하는 서해비단고둥(Umbonium thomasi)은 우리나라의 서해안과 중국연안에만 서식한다. 비단고둥 (U. costatum)보다 소형으로 낮은 원추형이고, 조간대의 모래사장에 살며 간조 때에는 모래 속으로 파고 들어간다. 껍질은 약간 푸르스름하고 꾸불꾸불한 회색 무되가 방사상으로 덮여 있으며 내부는 진주층으로 광택이 있다 (Yoo, 1976; Kwon et al., 1993). (중략)

• Animal cells and systems
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• v.5 no.1
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• pp.37-44
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• 2001

Gonadal development, reproductive cycle, gonad index, meat weight rate, and first sexual maturity of the top shell, Omphalius rusticus were Investigated monthly by histological observations. Specimens were collected from the west coast of Korea during the period from January to December in 1999. O. rusticus is dioecious and oviparous. The gonad is widely situated on the surface of the digestive g1and located in the posterior spiral meat part in the shell. The ovary and the testis were composed of a number of oogenic follicles and several spermatogenic follicles, respectively. Ripe oocytes were approximately 120-130 $\mu$m in diameter. The meat weight rate peaked in June (27.7%), and then rapidly decreased in September (19.5%). Monthly changes in the gonad index in both sexes reached the maximum in June, and then sharply decreased in September. Percentages of first sexual maturity of female and male snails ranging from 9.0 to 9.9 mm in shell heights were 58.3% and 54.5%, respectively, and 100% in those over 11.0 mm in both sexes participated in reproduction. Reproductive cycle of this species can be categorized into five successive stages: in females, early active (October to April), late active (December to June), ripe (April to September), spawning (July to September) and recovery (September to January): in males, early active (November to March), late active (December to June), ripe (April to September), spawning (July to September) and recovery (September to December). Gonadal development, gametogenesis, reproductive cycle, and spawning were closely related to the seawater temperature.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.65-104
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• 2007

This catalogue is the result of a four-year survey of the mollusks of Jeju Island, the southernmost island in the Republic of Korea. Forty-eight survey stations were visited, with a total of 82 specific localities being sampled. Literature records were also obtained. Local and world distribution of each species is included. This survey reports a total of 1,072 mollusk species and subspecies; 1,015 marine and 57 land and freshwater. There are 812 gastropods, of which 755 are either entirely marine or have marine affinities. The best represented of the marine families are the Pyramidellidae, Trochidae, and Ovulidae. There are 225 bivalves, none being freshwater species, with the Veneridae, Mytilidae, and Arcidae having the largest number of species. Among the smaller classes there are sixteen Cephalopoda, eleven Polyplacophora, and eight Scaphopoda. Compared to mainland Korea, Jeju Island has a rather small terrestrial mollusk fauna and a depauperate freshwater one, with mainly Palearctic connections. The Helixarionidae and Bradybaenidae are the largest terrestrial families. The marine faunal affinities with the neighboring Japonic and Indo-West Pacific provinces are also discussed, revealing that this island's mollusk fauna is a blend of warm-temperate and subtropical-tropical species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.702-708
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• 2002

Although Umboniunm thomasi is one of marine mollusc (Archaeogastropoda: Trochidae) inhabiting the sands in the intertidal zone of the west coast of Korea, aspects of its reproductive biology are still not too well known. Reproductive cycle, gametogenesis, and first sexual maturity of U. thomasi collected at the west coast of Buan-gun, Jeollabuk-do, Korea were investigated monthly from January to December 1999. U. thomasi was dioecious, and an oviparous. The gonad was placed in the rear of the flesh part in the spiral shell. The external colors of the ripe ovary and testis appeared to be green and milk-white or yellowish white, respectively. Meat weigh rate peaked in July ($37.5\%$). And then the value sharply decreased in September ($28.3\%$), thereafter, gradually increased in November ($31.7\%$). Fully ripe oocytes were approximately 100$\~$110 $/mu$m in diameter, and their cytoplasm contained a great number of yolk Branules. Based on the monthly changes of the Bonadal development, gametogenesis, and meat weight rate, the reproductive cycle of U. thomasi could be devided into five successive stages: early active (November to April), late active (February to May), ripe (April to August), spawning (July to October), and recovery (September to February). Gonadal development and spawning were closely related to the seawater temperature, the main spawning occurred in September when the temperature reached above 24.2$^{\circ}C$. Individuals of 4.4 mm and less in shell height could not take part in reproduction in both sexes. Percentages of first sexual maturity of female and male shells ranging from 5.5 to 6.4 mm were $55.0\%$ and $61.9\%$, respectively, and $100\%$ of those over 7.5 mm in shell heights in both sexes participated in the reproduction.