• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.279-284
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• 2010

Four leptocephali (TL 109.8~129.7 mm) of the family Ophichthidae, collected from Sangju in the South Sea of Korea, were identified using morphological and molecular methods. Our four leptocephali were similar to Ophichthus sp. based on morphological characters: the melanophores present in series of eight gut swellings; total myomeres 144~151; body depth in total length less than 10%; eight or nine black horizontal bands present from anus to caudal fin base. On the other hand, our four leptocephali were identified to Pisodonophis sp. based on 826 base pairs of 12S rRNA gene nucleotide sequences. Our results showed that morphology-based identification did not agree with molecular identification, indicating difficulty in differentiating morphologically between Ophichthus and Pisodonophis leptocephali. We, herein, firstly describe morphological characteristics of Pisodonophis sp. leptocephali from Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.594-597
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• 2013

Two leptocephali [total length (TL) 68.2-80.5 mm] from the family Ophichthidae, collected from the waters south of Jeju Island, Korea, were identified using morphology. The two ophichthid leptocephali were identified as belonging to the genus Ophichthus based on morphological characters: 131-132 myomeres; nine gut swellings; dorsal fin origin above the middle of the body; five postanal pigments present from the anus to the caudal margin. Ultimately, both leptocephali were identified as Ophichthus asakusae, as the total number of myomeres was consistent with those of adult O. asakusae. Here, we first describe the morphological characteristics of the O. asakusae leptocephalus, and suggest diagnostic characters for leptocephali belonging to the genus Ophichthus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.597-602
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• 2014

We determined the effects of starvation, water temperature, and water flow on the onset of metamorphosis in leptocephali of the Japanese eel Anguilla japonica. Leptocephali larger than 50 mm (ca. 200 days old) were reared in 10-L tanks under different feeding, water temperature, and water flow regimes. Fasted leptocephali metamorphosed earlier and faster than did the fed ones. Metamorphosis was faster in the high water flow tank (1.2 L/min) than in the tank with flow at 0.6 L/min. The duration of metamorphosis was slightly shorter at $26^{\circ}C$ than at $23^{\circ}C$. To conclude, starvation induced the metamorphosis of artificially produced leptocephali larger than 50 mm TL. Increased water flow and water temperature both appear to induce and shorten metamorphosis.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.59-64
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• 2013

Two leptocephali (36.2~69.2 mm in total length) of the family Muraenidae were collected off Jeju Island, Korea. They were identified using 742 base pairs of mitochondrial DNA 12S rRNA sequences, and their morphological description were presented. The two leptocephali were identified to Gymnothorax minor based on genetic distance (d=0.000), being well consistent with that of G. minor adult collected off Tongyeong. Gymnothorax minor leptocephali are characterized by morphological combinations: total myomeres 137~139, predorsal myomeres 32, preanal myomeres 82~86, body depth in total length more than 10%.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.217-224
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• 2011

The seven leptocephali (14.6~68.0 mm in total length) of the family Ophichthidae, from the East Sea of Korea, were identified using 12S rRNA 861-bp sequences and their morphological development were described. Our seven leptocephali were identified to Echelus uropterus based on genetic distance (d=0.000) being well consistent with that of adult E. uropterus. Our seven leptocephali of E. uropterus are characterized by morphological combinations: caudal fin present; the melanophores present in series of nine gut swellings; total myomeres 154~158; body depth in total length less than 10%; eight black horizontal bands present from anus to caudal fin base. Our morphological and molecular results suggest that E. uropterus may be an intermediate group between subfamily Ophichthinae and Myrophinae.

• Animal cells and systems
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• v.16 no.5
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• pp.415-424
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• 2012

Four species of ophichthid leptocephali were identified using 12S rDNA sequences, and their morphological descriptions were first provided based on six individuals (S1-S3,M1, and E1-E2) collected from the East Sea and the Korea Strait between September 2008 and October 2010. Mitochondrial 12S rDNA 859-861 base pairs of ophichthid leptocephali were compared with those of 16 ophichthids adult and 2 outgroups (Anguilla japonica and Conger myriaster). Leptocephali of S1 and E1 were very closely clustered with adult of Scolecenchelys borealis (D=0.002) and Echelus uropterus (D=0.000), respectively. However, leptocephali of S2-S3 andM1 were slightly far clustered with leptocephalus of S1 (D=0.006) and adult of Muraenichthys gymnopterus (0.034), respectively. We believe that S1 and E1 are S. borealis and E. uropterus, respectively, in which the former is unrecorded species in Korea. However, S2-S3 and M1 may be undescribed species belonging to genus Scolecenchelys and Muraenichthys, respectively, because total numbers of myomeres for S2-S3 (148-158) and M1 (151) were not consistent with total numbers of vertebrae or distribution for any adult of Scolecenchelys spp. and Muraenichthys spp. in the world. We propose the new Korean name 'Dong-hae-mul-baem' for S. borealis.

• Ocean Science Journal
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• v.41 no.4
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• pp.207-210
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• 2006

Leptocephali of the genus Saurenchelys in the family Nettastomatidae were collected from the coastal area of Pohang, Korea and described as the first record from Korean waters. S. stylura and S. lateromaculatus are characterized by two intestinal swellings, the pattern of pigments in the notochord, and by smaller pectoral fins than those of other genus. They are very similar to each other but they are distinguished by the pattern of pigments in the notochord and the intestinal swellings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.888-894
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• 2014

Seventeen specimens of leptocephali [9.8-44.5 mm total length (TL)], of the family Ophichthidae, were collected from southeastern waters off Jeju Island and the Korea-Japan intermediate zone, and identified by means of morphology and genetics. These specimens were identified as belonging to the subfamily Ophichthinae based on various combinations of morphological characters: 211-215 total myomeres; 7 gut swellings; 2 liver lobes connected with the gall bladder on the second lobe; 6-7 postanal pigments present from anus to caudal margin. An analysis of the partial 12S rRNA sequences (849 base pairs) of mitochondrial DNA showed that our specimens must be Ophisurus macrorhynchos because their sequences were concordant with those of the adult O. macrorhynchos (genetic distance = 0.000). Furthermore, their total myomeres were consistent with those of the O. macrorhynchos adult. This is the first time that the morphological characteristics of O. macrorhynchos leptocephali have been described for Korean waters, and we suggest diagnostic characteristics for the genus Ophisurus leptocephali. We hypothesize that one of the spawning grounds of O. macrorhynchos is located in the southeastern part of Jeju Island.

• Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.109-113
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• 2015

Three leptocephali (22.2, 22.7, 56.0 mm in total length) collected from the East/Japan Sea were identified by morphological and genetic analyses as belonging to the genus Scolecenchelys (Anguilliformes, Ophichthidae). Morphologically, the specimens were characterized by 148-158 myomeres, 10 gut swellings, dorsal fin origin above middle of the body, and 6 postanal melanophores between the anus and the caudal margin. An analysis of an 849-base pair 12S rRNA sequence of mitochondrial DNA showed that sequences are concordant with those of adult Scolecenchelys fuscogularis (genetic distance = 0.001). Furthermore total number of myomeres is consistent with the total number of vertebrae in adult S. fuscogularis. This study provides the first description of the morphological characteristics of S. fuscogularis leptocephali and their variations with size. The Korean name of S. fuscogularis is "Ga-neun-mul-baem", established by Ji et al. (2012).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.527-534
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• 2015

The twenty six specimens of leptocephali (15.8-32.6 mm TL) of the family Congridae, collected from southeastern waters offshore of Jeju Island during August 2014, and were identified by means of morphology and genetics. Those specimens were identified as belonging to the family Congridae based on various combinations of morphological characters. An analysis of the partial 12S rRNA sequences (886 base pairs) of mitochondrial DNA showed that our specimens must be Gnathophis nystromi, because their sequences were concordant with those of G. nystromi adult (genetic distance= 0.001), furthermore their total myomeres being consistent with those of G. nystromi adult. Catch rates of G. nystromi leptocephali were higher in the offshore regions than coastal regions of Jeju Island. The smallest leptocephali (< 20 mm TL) were collected offshore from Jeju Island. We hypothesize that one of the spawning grounds of G. nystromi is located offshore in the Jeju Island. In conclusion, the hatched preleptocephali of G. nystromi might have been transported from offshore near Jeju Island to the Korea Strait by the Kuroshio Current and Tsushima Warm Current.