Taiwan is one of the richest in the world in terms of eel fauna. In this study, we examined the osteological and morphological characteristics of eels under order Anguilliformes. Furthermore, we focused on the neurocranium of total of 30 Anguilliformes fishes under family Congridae (10), Muraenesocidae (1), Muraenidae (7), Nemichthyidae (1), Nettastomatidae (2), Ophichthidae (5), Synaphobranchidae (4), which are caught in Taiwanese waters. This paper shows the results of a comparative study on osteological characters of the neurocranium including the ratio of seven length characters using its NCL (neurocranium length), NCW (neurocranium width), OBL (orbit length), MFW (maximum frontal width), NCDB (neurocranium depth at basisphenoid), PEVW (premaxilla-ethmovomer width) and mPOBL (mid pre-orbital length), and 20 morphological diagnostic characters for 30 eel species. Results shows that species under family Nemichthyidae and Nettastomatidae have the highest values on the ratio of NCL/MFW, NCL/NCDB, and NCW/mPOBD. In morphological characters, it shows that species of the same family mostly share similar formation of the PEV plate and frontal structure. The usage of the length measurements and morphological diagnostic characters of neurocranium allowed for a more in depth understanding of how similar or different these eels can be. The neurocranial description and morphological characters may prove valuable for identification purposes and might be necessary tool for further studies on the status of order Anguilliformes.
Gymnothorax poikilospilus sp. nov. is described based on two specimens collected from Penghu Islands, western Taiwan. It is a medium-sized brown moray that body covered with several rows of inconspicuous large dark brown patches on the back of body and dorsal fin. It has slightly elongated and arched jaws similar to the common characteristic of the genus Enchelycore Kaup, but the dentition supports it belongs to typical morays of the genus Gymnothorax Bloch. The new species can be distinguished from other similar Indo-Pacific brown morays by the combination of dentition, vertebral formula, and morphometric measurements. Molecular analyses based on 612 bp of mitochondrial COI gene also support it as a distinct species.
The following nine elongate unpatterned muraenid species of the subfamily Muraeninae, including one new species, are recognized from Taiwan and adjacent waters: Gymnothorax albimarginatus (Temminck & Schlegel), G. dorsalis Seale, G. melanosomatus Loh, Shao & Chen, G. phasmatodes (Smith), G. prolatus Sasaki & Amaoka, G. sagmacephalus Böhlke, Pseudechidna brummeri (Bleeker), Strophidon sathete (Hamilton) and G. pseudomelanosomatus new species, described from two specimens. This new moray eel is distinguished from its similar species, G. melanosomatus, by the following features: grey brown body (vs. black), snout length 20.5% (vs. 17.8%) of head length, smaller eye diameter 8.2% (vs. 10.0%) of head length; preanal length 49.5% (vs. 58.5%) total length, and preanal vertebrae 89-89 (vs. 105-109). Phylogenetic relationships of the nine species were examined using nucleotide sequence data from partial sequences of mitochondrial ND5 gene (600 bp), and seven species form COI (600 bp). The genetic analyses suggest that G. pseudomelanosomatus is distinct from G. melanosomatus and the other six species of Gymnothorax. Morphological features and mitogenetic affinities strongly suggest that "G." dorsalis should be placed in Strophidon rather than in Gymnothorax. The results also suggest that employment of ND5 and COI gene sequences are rather useful for identification of species and for obtaining reasonable insights into the phylogeny of the muraenid species.
In this study, the complete mitogenome sequence of the Zebra moray, Gymnomuraena zebra (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,576 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Zebra moray is 30.2% for A, 26.8% for C, 17.2% for G, and 25.8% for T and show 80% identities to Kidako moray, Gymnothorax kidako. The complete mitogenome of the Zebra moray provides an essential and important DNA molecular data for further phylogeography and evolutionary analysis for moray eel phylogeny.
In this study, the complete mitogenome sequence of two moray eels of Gymnothorax formosus and Scuticaria tigrina (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome, with the length of 16,558 bp for G. formosus and 16,521 bp for S. tigrina, shows 78% identity to each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein coding genes, 22 transfer RNAs, two ribosomal RNAs genes, and a non-coding control region of D-loop. The length of D-loop is 927 bp (G. formosus) and 850 bp (S. tigrina), which is located between tRNA-Pro and tRNA-Phe. The overall GC content is 45.5% for G. formosus and 47.9% for S. tigrina. Complete mitogenomes of G. formosus and S. tigrina provide essential and important DNA molecular data for further phylogenetic and evolutionary analysis for moray eel.
In this study, the complete mitogenome sequence of the longfang moray, Enchelynassa canina (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The length of the assembled mitogenome is 16,592 bp, which includes 13 protein coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of longfang moray is 28.4% for A, 28.0% for C, 18.4% for G, 25.1% for T, and show 82% identities to Kidako moray, Gymnothorax kidako. The complete mitogenome of the longfang moray provides an essential and important DNA molecular data for further phylogeography and evolutionary analysis for moray eel phylogeny.