This study reviews all genera and species belonging to the family Bougainvilliidae from the South China Sea. The Nubiella atentaculata Xu and Huang, 2004 formerly included in the genus Nubiella, now is transferred to a new genus Paranubiella and included in the Bougainvilliidae as Paranubiella atentaculata (Xu and Huang, 2004) n. comb.. Two new species, Paranubiella nanhaiensis Xu, Huang and Guo, sp. nov. and Nubiella apapillaris Xu, Huang and Guo, sp. nov. from the South China Sea are described and illustrated in the present paper. In addition, the key to known genera of family Bougainvilliidae and species of genus Nubiella are described. Other data are briefly summarized to the list of species presented on the family Bougainvilliidae in the South China Sea. The type species were deposited at the Third Institute of Oceanography, State Oceanic Administration.

Four species of caridean shrimps collected from the East China Sea and South China Sea represent new records for the Chinese waters: Lysmata kempi Chace, 1997; Lysmata lipkei Okuno and Fiedler, 2010; Chlorocurtis jactans (Nobili, 1904) and Rhynchocinetes conspiciocellus Okuno and Takeda, 1992. The diagnostic characters and illustrations of these four species are presented, with remarks on their taxonomy. The identification keys of these species from Chinese waters are provided.

A neritid species Vittina pennata (von Born, 1778) is reported for the first time from the South China Sea. This is also the first report of this genus from Chinese waters. The specimen was collected from the Sanya Harbor, Hainan Province, China and deposited in Marine Biological Museum, Chinese Academy of Sciences. Detailed descriptions of its shell feature are presented. Differences between this species, Vittina coromandeliana and Neritina pulligera are compared and discussed.

Two new species of free living nematodes Tripyloides mangrovensis n. sp. and Tripyloides amoyanus n. sp. of genus Tripyloides de Man, 1886 are described from mangroves of the Tong’an Bay and Haimen Island in the Xiamen Bay, China. The two species are both characterized by six stout outer labial setae, male without preanal papillae, tail conico-cylindrical without swollen terminally. Tripyloides mangrovensis n. sp. can be additionally by its buccal cavity consisting of two parts, amphid circular, distinct proximal conical and distal slender cylindrical portions, 2/3 of the tail cylindrical. Tripyloides amoyanus n. sp. is distinguished by buccal cavity consisting of three parts with small tooth, amphid small, rounded, like a comma-shaped loop, 1/3 of the tail cylindrical, gubernaculum with four denticles.

Two new species of free-living marine nematodes of the genus Wieseria are described from the sublittoral sediment of the Jiaozhou Bay in Qingdao. Wieseria sinica sp. nov. is characterized by having short labial and cephalic setae in a backward direction; oblong amphidial foveas with double contour; arcuate spicules with alea; ring-like guberculum; and clavated tail. Wieseria tenuisa sp. nov. is characterized by its very large “a” value (133.6), long labial setae in a forward direction; spicules with alea and hooked proximal end; rodlike gubernaculums; and relatively longer clavated tail (7.9 a.b.d. long). It differs from Wieseria sinica sp. nov. mainly by the longer labial setae, slightly straight spicules with hooked proximal end, and its thinner body. Amended dichotomous key to male species of Wieseria is provided.

The living morphology and infraciliature of six spirotrichous ciliates collected from the coastal South China Sea were investigated using live observation and protargol impregnation. These are Euplotes woodruffi Gaw, 1939, Hemigastrostyla enigmatica (Dragesco and Dragesco-Kernéis, 1986) Song and Wilbert, 1997, Neourostylopsis flavicana (Wang et al., 2011) Chen et al., 2013, Protogastrostyla pulchra (Perejaslawzewa, 1886) Gong et al., 2007, Pseudoamphisiella alveolata (Kahl, 1932) Song and Warren, 2000, and Pseudokahliella marina (Foissner et al., 1982) Berger et al., 1985. Among these, Protogastrostyla pulchra, Pseudoamphisiella alveolata and Pseudokahliella marina are reported from the South China Sea for the first time, which manifest obvious differences apart from other Chinese populations. As new contribution, the detailed description of isolates from mangrove habitat of E. woodruffi and H. enigmatica, and aquaculture pond isolate of N. flavicana, are present.

One strain of unicellular greenish algae embedded by mucilage was successfully isolated from equatorial area in the Indian Ocean. Microscopic observation, ultrastructure features and genetic identification confirmed that the strain was closely related to Cyanothece sp., which was a cyanobacteria species with great ecological significance. Cells were solitary with oval or bacilliform shapes. Diameters of this strain were relatively small, ranging from 2.5 to 6.5 μm on average. Ultrastructure of cells was simple. Thylakoids were arranged parietal and keritomized content were observed in the thylakoid region. Various electron-transparent granules with low electron-dense region as well as cyanophycin or glycogen granules-like organelle and carbonxysomes were also observed. For pigment composition, the dominant pigments were chlorophyll a, β-Carotene, Zeaxanthin and an unknown pigment, contributing 23.8%, 26.1%, 14.7% and 15.7% to total pigments respectively. The phylogenetic analysis of 16S rRNA gene and nifH gene confirmed that Strain EIO409 was closely related with Cyanothece sp. .

Two new species of free-living marine nematodes of the genera Hopperia and Nemanema are described from the sublittoral sediment of the East China Sea. Hopperia macramphida sp. nov. is characterized by having large amphidial fovea with five turns; arcuate spicules with enlarged proximal end and central internal lamella extending one third of spicule length from proximal end; gubernaculum with bent apophyses, six papilliform precloacal supplements; and conico-cylindrical tail with swollen tip and terminal setae. Nemanema minutum sp. nov. is characterized by relatively smaller body size in the genus; large oval amphidial fovea; conical tail; slender spicules with alae and hooked proximal end; ring-like gubernaculum; and papilliform precloacal supplements with three short setae. An updated dichotomous key is provided for the 17 species of Hopperia.

Four species of Trichodina parasitizing the gills of cultured molluscs and fishes in China are described: Trichodina pectenis Stein, 1974 from the scallop Mizuhopecten yessoensis; Trichodina jadranica Raabe, 1958 from the fishes Mugil cephalus and Anguilla bicolor bicolor; Trichodina acuta Lom, 1961 and Trichodina rostrata Kulemina, 1968 from the fish Acrossocheilus fasciatus. The description of T. pectenis presented here first includes both live characters and morphometric data obtained from specimens impregnated using the wet silver nitrate and protargol methods. The other species were revealed by the dry silver nitrate method. Intensities of infestation and comparisons with related species and populations are provided for each of the four.

Actinonema falciforme sp. nov. was discovered from the continental-shelf sediments of the East China Sea. It is characterized by six outer labial setae and four cephalic setae in one circle, complex and heterogeneous cuticular ornamentation with lateral differentiation, large and conspicuous amphideal fovea which is transversely oval-shaped, a single anterior testis, two opposed reflexed ovaries, falciform telamon (lateral pieces of gubernaculum), and the lack of spicule and gubernaculum. Within the genus Actinonema, only A. longicaudatum and the new species possess telamon and lack spicule and gubernaculum. Actinonema falciforme sp. nov. can be easily differentiated from A. longicaudatum by its much shorter body length, the peculiar shape of the telamon and a shorter tail.