It is unreliable to identify marine fishes only by external morphological features. Species misidentification brings great challenges to fishery research, resource monitoring and ecomanagement. ...Sillago ingenuua is an important part of commercial marine fishes, and in which, the morphological differences between different groups are not obvious. Here, we compared different geographical groups of S. ingenuua which were collected from Xiamen, Dongshan, Keelung, Songkhla and Java. The results showed that all samples of S. ingenuua were similar in external morphological characteristics and the shape of the swim bladder, but there were two distinctive lineages which were flagged as cryptic species based on DNA barcoding. The comparative mitogenomic results showed that S. ingenuua A and S. ingenuua B were identical in structural organization and gene arrangement. Their nucleotide composition and codon usage were also similar. A phylogenetic analysis was performed based on 13 concatenated PCGs from eight Sillago species. The results showed that the genetic distance between S. ingenuua A and S. ingenuua B was large (D = 0.069), and this genetic distance was large enough to reveal that S. ingenuua A and S. ingenuua B might be different species.
More frequent global warming events, biological disasters, and anthropogenic activities have caused extensive damage to coral reefs around the world. Coral reefs in the Xisha Islands (also known as ...the Paracel Islands) have been damaged following rounds of heatwaves and crown-of-thorns starfish (CoTS) outbreaks over recent decades. Based on a comprehensive community survey in 2020, we determined a diagnosis for the present state of six coral regions in the Xisha Islands. The findings suggested that these regions had a total of 213 species of scleractinian corals belonging to 43 genera and 16 families. Living coral coverage across sites was widely divergent and ranged from 0.40% (IQR: 7.74-0.27%) in Panshi Yu to 38.20% (IQR: 43.00-35.90%) in Bei Jiao. Coral bleaching prevalence was 23.90% (IQR: 41.60-13.30%) overall and topped out at 49.30% (IQR: 50.60-48.10%) in Bei Jiao. Five of the coral regions (all but Yongxing Dao) were under threat of CoTS outbreaks. High mortality combined with excellent recruitment rates suggested potential rehabilitation after recent deterioration. We employed a quantifiable Deterioration Index (DI) to evaluate the intensity of deterioration of coral reefs in the Xisha Islands. The results showed that Yongxing Dao and Langhua Jiao had low recent deterioration (DIrecent = 0.05, IQR: 0.07-0.02 and 0.04, IQR: 0.11-0.01, respectively), while Bei Jiao, Yongle Atoll, Yuzhuo Jiao, and Panshi Yu had high recent deterioration (DIrecent > 0.16). Different monitoring sites within the same coral region were heterogeneous with regards to all above indexes. Moreover, we reviewed and discussed potential disturbances that threaten the health of the Xisha Islands' corals. It is crucial to identify severely afflicted areas and find successful methods to better manage coral reef health in this region.
A new
Sillago
species,
Sillago parasihama
sp. n., is identified based on 127 specimens collected from the southern coast of China. We compared the morphological characters between
Sillago parasihama
...and all other 11
Sillago
species with two posterior extensions on the swim bladder. The new species is like
S. sihama
in the countable characters and color pattern, but is different from the latter by the distinct swim bladders. The swim bladder of
S. parasihama
is without lateral process. The posterior sub-extensions of anterolateral extensions are unique with some dendritic or sometimes stunted blind tubule, which are unilateral and outward, extending along the abdominal, and are about one-third to half of the body of swim bladder in length. But the swim bladder of
S. sihama
with 8–10 lateral processes, the posterior sub-extensions of anterolateral extensions are kinky, long and complicated, extending along the abdominal wall below the peritoneum to the base of posterior extensions.
S. parasihama
can be distinguished from other species in this group by color pattern, meristic, and morphometric characters. Moreover, the results of genetic analysis using sequences of the mitochondrial cytochrome c oxidase subunit I (
COI
) fragment show significant interspecific-level genetic distances (0.159–0.231) between
S. parasihama
and 8 congeners in the group, which also support the validity of new species. We also provide a distribution map and a key of the related species.
A corallivorous nudibranch from the South China Sea reproduced explosively and caused extensive damage to Porites in our aquarium. In this study, morphological and molecular analyses of the ...nudibranch were conducted and described. Morphologically, this nudibranch was nearly consistent with Pinufius rebus in its characteristics intermediate between arminids and aeolids. The only detected difference was that the hook-like denticles on the masticatory border of P. rebus were absent in this nudibranch. In a molecular analysis, phylogenetic results based on the cytochrome oxidase subunit-I, 16S rRNA, and histone H3 gene sequences showed that this nudibranch and P. rebus form a well-supported sister clade under the superfamily Fionoidea, with significant interspecific divergence (0.18). Thus, we presumed that this nudibranch is a new species of Pinufius. Our results extend the distribution of Pinufius to the South China Sea, support the current taxonomic status of Pinufius under the superfamily Fionoidea, and imply that the species composition of Pinufius is more complex than previous records. Moreover, as a corallivorous nudibranch, the potential threat of Pinufius to coral health cannot be neglected.
In this study, the whole mitochondrial genomes of
Physogyra lichtensteini
and
Plerogyra sinuosa
have been sequenced for the first time. The length of their assembled mitogenome sequences were 17,286 ...bp and 17,586 bp, respectively, both including 13 protein-coding genes, two tRNAs, and two rRNAs. Their mitogenomes offered no distinct structure and their gene order were the same as other typical scleractinians. Based on 13 protein-coding genes, a maximum likelihood phylogenetic analysis showed that
Physogyra lichtensteini and Plerogyra sinuosa
are clustered in the family Plerogyridae, which belongs to the “Robust” clade. The 13 tandem mitogenome PCG sequences used in this research can provide important molecular information to clarify the evolutionary relationships amongst stony corals, especially at the family level. On the other hand, more advanced markers and more species need to be used in the future to confirm the evolutionary relationships of all the scleractinians.
Sediment core samples were collected from 17 stations in the middle and eastern Chukchi Sea during the sixth Chinese National Arctic Research Expedition (CHINARE-Arctic) in summer 2014. The samples ...were analyzed for composition, abundance, biomass, vertical distribution, size spectra, and ecological indexes of meiofauna. A total of 14 meiofauna taxa were detected, and the free-living marine nematodes comprised the most dominant taxon, accounting for 97.21% of the average abundance. The abundance and biomass of meiofauna were within ranges of (218.12±85.83)−(7 239.38±1 557.15) ind./(10 cm
2
) and (130.28±52.17)−(3 309.56±1 751.80) μg/(10 cm
2
), with average values of (2 391.90±1 966.19) ind./(10 cm
2
) and (1 549.73±2 042.85) μg/(10 cm
2
) (according to dry weight) respectively. Furthermore, 91.26% of the individuals were distributed in the top layer of 0–5 cm of surface sediment, and 90.84% had sizes of 32–250 μm. Group diversity index of meiofauna in the survey area was low, and the variation of abundance was the main difference in meiofauna communities among all stations. Abundance and biomass of meiofauna were not significantly correlated with environmental factors except concentration of nutrient Si in bottom seawater. Abundance of meiofauna in shallow water of marginal seas in the Pacific sector of the Arctic Ocean is likely at a same level and higher than that in most of China sea areas, suggesting that the shallow water of the summer Chukchi Sea is a continental shelf area with rich resources of meiofauna. The Chukchi Sea is important for studying the ecosystem of the Arctic Ocean and environmental responses. However, studies on meiofauna in the Chukchi Sea are still not enough, and in the future, natural and human disturbances may increase due to global warming, the Arctic channel opening, and other factors. Thus, more studies on meiofauna should be required, in order to know more about how the Arctic benthic community would alter.
Lack of mitochondrial genome data of Scleractinia is hampering progress across genetic, systematic, phylogenetic, and evolutionary studies concerning this taxon. Therefore, in this study, the ...complete mitogenome sequence of the stony coral
Echinophylliaaspera
(Ellis & Solander, 1786), has been decoded for the first time by next generation sequencing and genome assembly. The assembled mitogenome is 17,697 bp in length, containing 13 protein coding genes (PCGs), two transfer RNAs and two ribosomal RNAs. It has the same gene content and gene arrangement as in other Scleractinia. All genes are encoded on the same strand. Most of the PCGs use ATG as the start codon except for ND2, which uses ATT as the start codon. The A+T content of the mitochondrial genome is 65.92% (25.35% A, 40.57% T, 20.65% G, and 13.43% for C). Bayesian and maximum likelihood phylogenetic analysis have been performed using PCGs, and the result shows that
E.aspera
clustered closely with
Sclerophylliamaxima
(Sheppard & Salm, 1988), both of which belong to Lobophylliidae, when compared with species belonging to Merulinidae and other scleractinian taxa used as outgroups. The complete mitogenome of
E.aspera
provides essential and important DNA molecular data for further phylogenetic and evolutionary analyses of corals.
Reef-building coral species of the order Scleractinia play an important role in shallow tropical seas by providing an environmental base for the ecosystem. The molecular data of complete ...mitochondrial genome have become an important source for evaluating phylogenetic and evolutionary studies of Scleractinia. Here, the complete mitogenome of
(Milne Edwards and Haime, 1857), collected from Nansha Islands of the South China Sea, was sequenced for the first time through a next-generation sequencing method.
is the first species of its genus for which the mitogenome was sequenced. This mitogenome was 18,154 bp in size and included two transfer RNA genes (tRNAs), 13 protein-coding genes (PCGs), and two ribosomal RNA genes (rRNAs). It showed a similar gene structure and gene order to the other typical scleractinians. All 17 genes were encoded on the H strand and the total GC content was 33.86% in mitogenome. Phylogenetic analysis (maximum likelihood tree method) showed that
belonged to the "Robust" clade and clustered together with other two species in the family Lobophylliidae based on 13 PCGs. The mitogenome can provide significant molecular information to clarify the evolutionary and phylogenetic relationships between stony corals and to facilitate their taxonomic classification; it can also support coral species monitoring and conservation efforts.
Mitochondrial genome DNA is a powerful marker for resolving phylogenetic relationships among scleractinian corals. Here, we decode the complete mitochondrial genome of Diploastrea heliopora (Lamarck, ...1816) for the first time. The general features are 18 363 bp in length, and conventionally, with 13 protein coding genes, two ribosomal RNAs, and two transfer RNAs. Gene arrangement and distribution are similar to other scleractinian corals. Moreover, the COI gene of D. heliopora is broken up into two parts by a complex group I intron. This intron is 1076 bases in length and contains helical structures (P1-P10, except P2) and four conserved regions (P, Q, R, and S). The mitochondrial genome of D. heliopora has asymmetric base composition (13.03% C, 20.29% G, 25.91% A, and 40.77% for T). Based on concatenated protein coding genes, ML and BI trees show similar phylogenetic relationship: D. heliopora clustered closely with Sclerophyllia maxima and Echinophyllia aspera into the robust branch. The data and conclusion in this study are reference for further phylogenetic studies of corals.
Over the past few decades, modern coral taxonomy, combining morphology and molecular sequence data, has resolved many long-standing questions about scleractinian corals. In this study, we sequenced ...the complete mitochondrial genomes of three Merulinidae corals (
,
, and
) for the first time using next-generation sequencing. The obtained mitogenome sequences ranged from 16,466 bp (
) to 18,006 bp (
) in length, and included 13 unique protein-coding genes (PCGs), two transfer RNA genes, and two ribosomal RNA genes . Gene arrangement, nucleotide composition, and nucleotide bias of the three Merulinidae corals were canonically identical to each other and consistent with other scleractinian corals. We performed a Bayesian phylogenetic reconstruction based on 13 protein-coding sequences of 86 Scleractinia species. The results showed that the family Merulinidae was conventionally nested within the robust branch, with
clustered closely with
and
clustered closely with
. This study provides novel insight into the phylogenetics of species within the family Merulinidae and the evolutionary relationships among different Scleractinia genera.
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