A new species of the genus Litarcturus Brandt, 1990, L. kexueiae sp. nov., collected from deep sea of the Okinawa Trough, is described and illustrated. It is readily distinguished from the other seven species of the genus by bearing long supraocular spines about as long as the head and posterolateral pleotelsonic spines overreaching the pleotelson apex.
Abstract A new species of Eusiridae, Eusirus liui sp. nov. is described from a hydrothermal vent on Okinawa Trough, North-West Pacific. The new species differs from the other 30 congeneric species mainly by the following combination of characters: the acute rostrum reaching to 1/3 the length of peduncular article 1 of antenna 1; the absence of eyes; pleonite 3 without acute protrusion on dorsal margin, and the posterior margin of epimeron 3 with 18 serrations. A key to all known Eusirus species is provided herein. This is the fourth species within the Eusiridae that has been found from vent fields.
Shrimps of the family Alvinocarididae, endemic species to deep sea chemosynthetic ecosystems, harbor epibiotic microbes on gills which probably play important roles in the survival of the shrimps. Among them, Alvinocaris longirostris and Shinkaicaris leurokolos occupy different ecological niches within the same hydrothermal vent in Okinawa Trough, and A. longirostris also exists in a methane seep of the South China Sea. In this study, full-length 16S rRNA sequences of the gill associated bacteria of two alvinocaridid species from different chemosynthetically ecological niches were first captured by single-molecule real-time sequencing. Totally, 120,792 optimized circular consensus sequences with ∼1,450 bp in length were obtained and clustered into 578 operational taxonomic units. Alpha diversity analysis showed seep A. longirostris had the highest species richness and evenness (average Chao1 = 213.68, Shannon = 3.39). Beta diversity analysis revealed that all samples were clearly divided into three groups, and microbial community of A. longirostris from seep and vent were more related than the other comparisons. By permutational multivariate analysis of variance, the most significant community compositional variance was detected between seep A. longirostris and vent S. leurokolos ( R 2 = 0.731, P = 0.001). The taxon tags were further classified into 21 phyla, 40 classes, 89 orders, 124 families and 135 genera. Overall, the microbial communities were dominated by Campylobacteria and Gammaproteobacteria. Alphaproteobacteria, Bacteroidia, Verrucomicrobiae, Bacilli and other minor groups were also detected at lower abundance. Taxonomic groups recovered from the vent S. leurokolos samples were only dominated by Sulfurovaceae (94.06%). In comparison, gill-associated microbiota of vent A. longirostris consisted of more diverse sulfur-oxidizing bacteria, including Sulfurovaceae (69.21%), Thiotrichaceae (6.77%) and a putative novel Gammaproteobacteria group (14.37%), while in seep A. longirostris , Gammaproteobacteria un-group (44.01%) constituted the major component, following the methane-oxidizing bacteria Methylomonadaceae (19.38%), and Sulfurovaceae (18.66%). Therefore, the gill associated bacteria composition and abundance of alvinocaridid shrimps are closely related to the habitat heterogeneity and the selection of microbiota by the host. However, the interaction between these alvinocaridid shrimps and the epibiotic communities requires further study based on metagenome sequencing and fluorescence in situ hybridization.
Seba longimera sp. nov. , of the family Sebidae Walker, 1908, is described from hydrothermal vents in Okinawa Trough. Other two congenic species, S. bathybia Larsen, 2007 and S. profundus Shaw, 1989, are also reported from these hydrothermal vents, but the new species can be readily distinguished from them in having the merus of pereopods 5 and 6 extending beyond distal margin of carpus, coxa 4 smaller than coxae 2 and 3, and coxa 5 with the posterior lobe larger than the anterior one, rather than equilobate.
Abstract The deep sea (> 200 m) is considered as the largest and most remote biome, which characterized by low temperatures, low oxygen level, scarce food, constant darkness, and high hydrostatic pressure. The sea stars (class Asteroidea) are ecologically important and diverse echinoderms in all of the world’s oceans, occurring from the intertidal to the abyssal zone (to about 6000 m). To date, the phylogeny of the sea stars and the relationships of deep-sea and shallow water groups have not yet been fully resolved. Here, we recovered five mitochondrial genomes of deep-sea asteroids. The A+T content of the mtDNA in deep-sea asteroids were significantly higher than that of the shallow-water groups. The gene orders of the five new mitogenomes were identical to that of other asteroids. The phylogenetic analysis showed that the orders Valvatida, Paxillosida, Forcipulatida are paraphyletic. Velatida was the sister order of all the others and then the cladeValvatida-Spinulosida-Paxillosida-Notomyotida versus Forcipulatida-Brisingida. Deep-sea asteroids were nested in different lineages, instead of a well-supported clade. The tropical Western Pacific was suggested as the original area of asteroids, and the temperate water was initially colonized with asteroids by the migration events from the tropical and cold water. The time-calibrated phylogeny showed that Asteroidea originated during Devonian-Carboniferous boundary and the major lineages of Asteroidea originated during Permian–Triassic boundary. The divergence between the deep-sea and shallow-water asteroids coincided approximately with the Triassic-Jurassic extinction. Total 29 positively selected sites were detected in fifteen mitochondrial genes of five deep-sea lineages, implying a link between deep-sea adaption and mitochondrial molecular biology in asteroids.
A total of 5 species of the genus Kamaka (Crustacea: Amphipoda) are identified from Hainan Province, South China Sea. In those, one species, Kamaka excavata Ariyama, 2007, is recorded for the first time in Chinese waters. Two new species, Kamaka corophina sp. n. and Kamaka foliacea sp. n., are described. A key to the Chinese species is provided. They were collected from littoral zone, mud flat in seaweed of mangrove side, brackish water and seawater, sifted out with sieve.
A calcified individual of Epimeria Costa, 1851 collected from an unnamed seamount of the Caroline Plate, NW Pacific, is recognized as new to science herein. This increases the number of known Epimeria species of the North Pacific to nine. Epimeria liuisp. nov. differs from its similar congeners by having a rostrum hardly reaching to the end margin of first peduncular article of antenna 1, the presence of large pyriform eyes, the size-increasing mid-dorsal teeth starting from pereonite 6 to pleonite 2, the projection on coxa 5 not extending to epimeral plate 1, and by having a nearly quadrate telson notched medially. To facilitate identification the new species is included in a key to Pacific species of Epimeria.
Echinoids are an important component in benthic marine environments, which occur at all depths from the shallow-water hard substrates to abyssal depths. To date, the phylogeny of the sea urchins and the macro-evolutionary processes of deep-sea and shallow water groups have not yet been fully resolved. In the present study, we sequenced the complete mitochondrial genomes (mitogenomes) of four deep-sea sea urchins (Echinoidea), which were the first representatives of the orders Aspidodiadematoida, Pedinoida and Echinothurioida, respectively. The gene content and arrangement were highly conserved in echinoid mitogenomes. The tRNA-Ser AGY with DHU arm was detected in the newly sequenced echinoid mitogenomes, representing an ancestral structure of tRNA-Ser AGY . No difference was found between deep-sea and shallow water groups in terms of base composition and codon usage. The phylogenetic analysis showed that all the orders except Spatangoida were monophyletic. The basal position of Cidaroida was supported. The closest relationship of Scutelloida and Echinolampadoida was confirmed. Our phylogenetic analysis shed new light on the position of Arbacioida, which supported that Arbacioida was most related with the irregular sea urchins instead of Stomopneustoida. The position Aspidodiadematoida (((Aspidodiadematoida + Pedinoida) + Echinothurioida) + Diadematoida) revealed by mitogenomic data discredited the hypothesis based on morphological evidences. The macro-evolutionary pattern revealed no simple onshore-offshore or an opposite hypothesis. But the basal position of the deep-sea lineages indicated the important role of deep sea in generating the current diversity of the class Echinoidea.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
