Alleurythoe, a new genus with type species Alleurythoe tenuichaeta sp. n., is described and illustrated based on material from Beibu Gulf, northwestern South China Sea. The new genus is distinguished from all genera within Amphinomidae by a combination of characters: caruncle trilobed, conspicuous, attached to and confluent with the posterior prostomial lobe, which is free from the body wall and has 6-7 folds on each of the lateral lobes; both noto- and neuropodial aciculae are spinose, extending beyond the chaetal lobe. Alleurythoe tenuichaeta sp. n. is characterized by having branchiae present from chaetiger 4 and a bifurcate neurochaetae capillary. A key distinguishing the genera of Amphinominae is provided.

A review of 37 bopyrid isopods known to infest 43 species of caridean shrimps in China is presented, based on literature records and new material. Synonymies are provided for all species, with descriptions and detailed illustrations given for species represented by material examined herein. Bopyrids recorded as new species or new Chinese records belong to the subfamilies Argeiinae (2 or 3 species, depending on the identity of Argeia sp.: Argeia pugettensis Dana, 1852, Argeia sp., Stegoalpheon kempi Chopra, 1923), Pseudioninae (2 species: Paranikione sibogae, n. gen. n. sp., and Paranikione distorta, n. sp.), Bopyrinae (13 species: Bathygyge grandis Hansen, 1897, Bopyrella articulata, n. sp., Bopyrinella parameces, n. sp., Bopyrione multifeminae, n. sp., Bopyroides hippolytes (Kröyer, 1838), Bopyroides shiinoi Rybakov and Andeev, 1991, Parabopyrella cuspidata, n. sp., Parabopyrella distincta (Nierstrasz and Brender à Brandis, 1923), Parabopyrella elongata (Shiino, 1949), Parabopyrella hodgarti (Ch...

The deep-sea chemosynthetic environment is one of the most extreme environments on the Earth, with low oxygen, high hydrostatic pressure and high levels of toxic substances. Species of the family Vesicomyidae are among the dominant chemosymbiotic bivalves found in this harsh habitat. Mitochondria play a vital role in oxygen usage and energy metabolism; thus, they may be under selection during the adaptive evolution of deep-sea vesicomyids. In this study, the mitochondrial genome (mitogenome) of the vesicomyid bivalve Calyptogena marissinica was sequenced with Illumina sequencing. The mitogenome of C. marissinica is 17,374 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes (rrnS and rrnL) and 22 transfer RNA genes. All of these genes are encoded on the heavy strand. Some special elements, such as tandem repeat sequences, “G(A)_nT” motifs and AT-rich sequences, were observed in the control region of the C. marissinica mitogenome, which is involved in the regulation of replication and transcription of the mitogenome and may be helpful in adjusting the mitochondrial energy metabolism of organisms to adapt to the deep-sea chemosynthetic environment. The gene arrangement of protein-coding genes was identical to that of other sequenced vesicomyids. Phylogenetic analyses clustered C. marissinica with previously reported vesicomyid bivalves with high support values. Positive selection analysis revealed evidence of adaptive change in the mitogenome of Vesicomyidae. Ten potentially important adaptive residues were identified, which were located in cox1, cox3, cob, nad2, nad4 and nad5. Overall, this study sheds light on the mitogenomic adaptation of vesicomyid bivalves that inhabit the deep-sea chemosynthetic environment.

This work reports on a preliminary taxonomic study of epibenthic macroinvertebrates collected or observed by underwater video at the Haima cold seeps and in adjacent deep-sea habitats, including a mud volcano field and Ganquan Plateau, during an expedition in the South China Sea by the Chinese-manned submersible Shenhai Yongshi in May 2018. A total of 41 species belonging to 6 phyla were identified, among which 34 species were collected from the Haima cold seeps. Mollusks and crustaceans that are specialized in reducing habitats were predominant in biotopes of the Haima cold seeps, whereas sponges and cold-water corals and their commensals were prominent in communities of the mud volcano field and the slopes of Ganquan Plateau. The distribution and faunal composition of each taxonomic group are discussed.