Kang-Ning Shen

Genus-level taxonomic changes implied by the mitochondrial phylogeny of grey mullets (Teleostei: Mugilidae)

A comprehensive mitochondrial phylogeny of the family Mugilidae (Durand et al., Mol. Phylogenet. Evol. 64 (2012) 73-92) demonstrated the polyphyly or paraphyly of a proportion of the 20 genera in the family. Based on these results, here we propose a revised classification with 25 genera, including 15 genera currently recognized as valid (Agonostomus, Aldrichetta, Cestraeus, Chaenomugil, Chelon, Crenimugil, Ellochelon, Joturus, Mugil, Myxus, Neomyxus, Oedalechilus, Rhinomugil, Sicamugil and Trachystoma), 7 resurrected genera [Dajaus (for Agonostomus monticola), Gracilimugil (for Liza argentea), Minimugil (for Sicamugil cascasia), Osteomugil (for several species currently under Moolgarda and Valamugil, including M. cunnesius, M. engeli, M. perusii, and V. robustus), Planiliza (for Indo-Pacific Chelon spp., Indo-Pacific Liza spp., and Paramugil parmatus), Plicomugil (for Oedalechilus labiosus), and Squalomugil (for Rhinomugil nasutus)] and 3 new genera: Neochelon gen. nov. (for Liza falcipinnis), Parachelon gen. nov. (for L. grandisquamis) and Pseudomyxus gen. nov. (for Myxus capensis). Genus Chelon was shown to include exclusively Chelon spp. and Liza spp. from the Atlantic and the Mediterranean, and Liza spp. species endemic to eastern southern Africa. Genus Crenimugil should now include C. crenilabis, Moolgarda seheli and V. buchanani. Genus names Liza, Moolgarda, Paramugil, Valamugil and Xenomugil should be abandoned because they are no longer valid. Further genetic evidence is required to confirm or infirm the validity of the genus Paracrenimugil Senou 1988. The mitochondrial phylogeny of the 25 genera from the present revision is the following: [(Sicamugil, (Minimugil, Rhinomugil)); Trachystoma; ((Myxus, Neomyxus), (Cestraeus, Chaenomugil, (Agonostomus, Dajaus, Joturus), Mugil)); (Aldrichetta, Gracilimugil); Neochelon gen. nov.; (Pseudomyxus gen. nov., (Chelon, Oedalechilus, Planiliza, Parachelon gen. nov.)); ((Squalomugil, (Ellochelon, Plicomugil)), (Crenimugil, Osteomugil))]. Agonostomus monticola and several species with large distribution ranges (including Moolgarda seheli, Mugil cephalus and M. curema) consist of separate lineages whose geographic distribution suggests they are cryptic species, thus warranting further taxonomic work in the Mugilidae at the infra-generic level.

Mitochondrial Haplotypes Indicate Parapatric-like Phylogeographic Structure in Blue-Spotted Maskray (Neotrygon kuhlii) from the Coral Triangle Region

Phylogeographic structure was investigated in the blue-spotted maskray, Neotrygon kuhlii, focusing on the Coral Triangle region. We used as genetic marker a 519-bp fragment of the cytochrome c-oxidase subunit I (COI) gene, sequenced in a total of 147 individuals from 26 sampling locations. The parsimony network of COI haplotypes was split into seven distinct clades within the Coral Triangle region. Different clades had exclusive but contiguous geographic distributions, indicating parapatric-like phylogeographic structure. Strong genetic differences were also inferred between local populations within a clade, where reciprocal monophyly between geographically adjacent samples was observed on several instances. Nearly 25% of the total molecular variance could be ascribed to differences between geographic samples within a clade, whereas interclade variation accounted for >65% of the total variance. The strong phylogeographic structure observed within a clade can be explained by either sedentarity or female philopatry. We interpret the parapatric distribution of clades as the joint result of 1) expansion from refuge populations at times of low sea level, and 2) possible enhanced competition between individuals from different clades, or assortative mating, or hybrid zones, along lines of secondary contact. The parapatric-like structure uncovered in the present study parallels regional differences at nuclear marker loci, thus pointing to incipient speciation within Coral Triangle N. kuhlii.

Next-generation sequencing yields the complete mitogenome of massive coral, Porites lutea (Cnidaria: Poritidae)

Abstract In this study, the complete mitogenome sequence of massive coral, Porites lutea (Cnidaria: Poritidae), has been sequenced by next-generation sequencing method. The overall base composition of Porites lutea mitogenome is 26.0% for A, 13.3% for C, 23.0% for G and 37.8% for T and have high AT content of 63.7%. The assembled mitogenome, consisting of 18 646 bp, has unique 13 protein-coding genes (PCGs), seven transfer RNAs and two ribosomal RNAs genes. The Porites lutea mitogenome has the common mitogenome gene organization and feature of scleractinian coral. Among 13 PCGs, ND5 and COX1 genes are interrupted by group I intron (11 130 and 971 bp, respectively). There are 13 genes embedded in ND5 group I intron (tRNA-Glu, ND1, CYTB, tRNA-Met, ND2, ND6, ATP6, ND4, 12S rRNA, COX3, COX2, ND4L and ND3), and two genes embedded in COX1 group I intron (tRNA-Ile and tRNA-Pro). The complete mitogenome provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for stony coral.

Lemonpeel (Centropyge flavissima) and yellow (C. heraldi) pygmy angelfishes each consist of two geographically isolated sibling species

Genetic variation was examined in two complex cases of Indo-Pacific pygmy angelfishes (genus Centropyge; Pomacanthidae). The lemonpeel pygmy angelfish C. flavissima (Cuvier and Valenciennes) has a geographically disjunct Indian vs. Pacific distribution and the individuals from these two regions differ by their colour patterns. Previous research on C. flavissima has shown mitochondrial introgression from two related species, C. eibli in the eastern Indian Ocean and C. vrolikii in the Pacific Ocean. Using the 16S rDNA and the CO1 gene as phylogeographic markers, we found no mitochondrial haplotypes in common between Indian Ocean C. flavissima and C. eibli, confirming partial genetic isolation, albeit recent. Also, we found substantial genetic differences between Indian and Pacific C. flavissima populations at the nuclear ETS-2 intron locus. The Indian Ocean form of C. flavissima, thus geographically isolated by >2000 km distance from its Pacific Ocean counterpart, is described as a new species, Centropyge cocosensis sp. nov. Centropyge cocosensis sp. nov. differs in appearance from C. flavissima in having a conspicuous blue iris and a fainter, bluish eye ring. We also found that the yellow pygmy angelfish C. heraldi Woods and Schultz consists of two genetically distinct entities, one distributed widely in the northern tropical Indo-West Pacific, the other distributed in the southern Pacific Ocean. The name originally given to the blackfin pygmy angelfish, C. woodheadi Kuiter, is here resurrected to designate the latter.

The complete chloroplast genome of Gracilariopsis lemaneiformis, an important economic red alga of the family Gracilariaceae

Abstract The complete chloroplast DNA (cpDNA) of a famous red alga of the family Gracilariaceae, Gracilariopsis lemaneiformis, was deduced by using next-generation sequencing and de novo assembly technology. The complete cpDNA of G. lemaneiformis consists of 182 505 bp and encodes 230 unique genes consisting 204 protein-coding genes (PCGs), 21 transfer RNA genes, 3 ribosomal RNA genes, 1 transfer-messenger RNA genes and 1 non-coding RNA genes. Among 204 PCGs, ccsA gene is interrupted by a intron. Unlike the typical quadripartite structure (a pair of inverted repeats separated by the small single-copy and large single-copy units) of cpDNA in higher plants, the complete cpDNA of G. lemaneiformis is very compact, containing no inverted repeat and just one copy of rRNA gene cluster consisting of 16S, 23S and 5S rRNA genes. The genic regions account for 83.7% of whole cpDNA genome, and the G + C content of the cpDNA was 27.4%. The low G + C content of G. lemaneiformis cpDNA is largely contributed by high A + T content in the PCGs and non-coding regions. A phylogenetic analysis of the 15 complete cpDNA from rhodophyta shows that G. lemaneiformis is closely related to macroalga Gracilaria salicornia. The complete cpDNA of G. lemaneiformis provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for rhodophyta.

Next generation sequencing yields complete mitogenomes of Leopard whipray (Himantura leoparda) and Blue-spotted stingray (Neotrygon kuhlii) (Chondrichthyes: Dasyatidae)

Abstract The Leopard whipray (Himantura leoparda) and Blue-spotted stingray (Neotrygon kuhlii) are distributed in the Indian and West Pacific Ocean and considered as complex species based on morphological and molecular evidences. In this study, we used the next-generation sequencing method to decode two complete mitogenomes of H. leoparda and N. kuhlii. The assembled mitogenome, consisting lengths of 17,690 bp for H. leoparda and 17,974 bp for N. kuhlii, shows 78% identity to each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes and a non-coding control region of D-loop. D-loop with the lengths 1931 bp (H. leoparda) and 2243 bp (N. kuhlii) is located between tRNA-Pro and tRNA-Phe. The overall GC content is 40.3% for H. leoparda and 39.8% for N. kuhlii. The complete mitogenome of H. leoparda and N. kuhlii provides essential and important DNA molecular data for further phylogenetic and evolutionary analyses for stingray species complex.

Spawning segregation and philopatry are major prezygotic barriers in sympatric cryptic Mugil cephalus species

The flathead mullet, Mugil cephalus, is a commercially vital fish in fisheries and aquaculture worldwide. Genetic analyses have recently revealed three cryptic species of M. cephalus in the Northwest Pacific. These species are sympatric in Taiwanese waters and specific reproductive behaviors have been suggested to be a major prezygotic barrier. Species composition was evaluated in samples of M. cephalus at different growth stages collected from various habitats (offshore spawning ground, estuarine nursery and feeding areas) over several months or years. The gonadosomatic index of adults and the body length of juveniles were recorded to determine the reproductive season and recruitment periods in estuaries. The results revealed partially temporal spawning isolation between species pairs, spatial segregation on specific spawning grounds and strong philopatry preclude hybridization. Thus, the results imply that traditional fisheries of mature fish in the Taiwan Strait target only one species, whereas aquaculture in Taiwan contain juveniles of all three species collected in estuaries. The ecological niche and demography of these species must be investigated further to estimate the impact of juvenile sources on aquaculture.

Low-coverage genome sequencing yields the complete mitogenome of Pyjama Slug, Chromodoris quadricolor (Mollusca: Chromodorididae)

Abstract In this study, the complete mitogenome sequence of Pyjama Slug, Chromodoris quadricolor (Mollusca: Chromodorididae), has been decoded for the first time by low-coverage genome-sequencing method. The overall base composition of C. quadricolor mitogenome is 30.6% for A, 14.4% for C, 17.8% for G and 37.2% for T and has low GC content of 32.2%. The assembled mitogenome, consisting of 14 259 bp, has unique 13 protein-coding genes (PCGs), 22 transfer RNAs and two ribosomal RNAs genes. The C. quadricolor mitogenome has the common mitogenome gene organization and feature of Nudipleura (a clade of sea slugs and sea snails). The complete mitogenome provides essential and important DNA molecular data for further evolutionary analysis for sea slugs and sea snails.

One Species Hypothesis to Rule Them All: Consistency Is Essential to Delimitate Species

The newly-desribed Centropyge cocosensis has long been considered a variant of the lemonpeel pygmy angelfish C. flavissima because of their overall similarity in color patterns. DiBattista and co-authors [J. Hered. 107 (2016) 647–653] recently contested the validity of C. cocosensis, based on arguments that are challenged here.

De novo assembly and comparison of the ovarian transcriptomes of the common Chinese cuttlefish (Sepiella japonica) with different gonadal development.

The common Chinese cuttlefish (Sepiella japonica) has been considered one of the most economically important marine Cephalopod species in East Asia and seed breeding technology has been established for massive aquaculture and stock enhancement. In the present study, we used Illumina HiSeq2000 to sequence, assemble and annotate the transcriptome of the ovary tissues of S. japonica for the first time. A total of 53,116,650 and 53,446,640 reads were obtained from the immature and matured ovaries, respectively (NCBI SRA database SRX1409472 and SRX1409473), and 70,039 contigs (N50 = 1443 bp) were obtained after de novo assembling with Trinity software. Digital gene expression analysis reveals 47,288 contigs show differential expression profile and 793 contigs are highly expressed in the immature ovary, while 38 contigs are highly expressed in the mature ovary with FPKM > 100. We hope that the ovarian transcriptome and those stage-enriched transcripts of S. japonica can provide some insight into the understanding of genome-wide transcriptome profile of cuttlefish gonad tissue and give useful information in cuttlefish gonad development.